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Bosch K-Jetronic Fuel Injection Part 1

1. pressure in the upper chambers then the dia phragm separating the upper and lower chambers is deflected downward and fuel can to the injectors When the pressure inside t jectors exceeds 30 pei the injectors will open and fuel will pad into the intake manifold The Lambda als the aystem computer to alter the ERE through the electrohydraulic actuglor in order to trim and correct the air fuel ratio The throttle awit used in conjunction with the airflow potentiometer to signal the system v engine load If the system computer detects an increasing airflow and a wide open throttle the current through the electro hydraulic actuator is increased the Lambda sor is ignored and the mixture is enriched V the throttle switch indicates a closed throttle and the airflow potentiometer indicates a decreasing airflow the current through the electrohydraulic actuator is reversed This reversed current cuts off fuel KE Jetronic Adjustments Because af the computer control of amd idle speed the number of manual on the RKE Jetronic system is limited Audi and Volkswagen Seven adjustments need ta be made on Audi and Volkewagen applications to accommodate the KE system During a normal tune up these adjust mente do not need to be tested Should any major injection components such as the fuel distributor be replaced however these adjustments should be checked They should also be checked ifa driveahil ity or fuel economy problem is prese
2. At the same time the pressure in the upper chambers changes by the same amount This in turn results in a change in the difference at the metering slits between the upper chamber pressure and the primary pressure and this is applied as a means for varying the fuel quantity delivered to the injection valves As a result of the small electromagnetic time constants and the small masses which must be moved the pressure actuator reacts extremely quickly to lia 4T srs PP Bo 6 hone ill Inknawn Zone A KE Jetronic 25 L L ra LILI LILI 3 He C Diagnosing Bosch KE Jetronic Injection If you ve done much work on European cars you ve encountered Robert Bosch K Jetronic mechanical fuel injection which first appeared in the early seventies It s an efficient multi port continuous the K stands for that word auf Deutsch spray system that works so well it allowed some car makers to avoid adding catalytic converters for a few years after everybody else needed them to comply with emissions regulations Yet it s less expensive than regular electronic port injection better than TBI Throttle Body Injection because it doesn t allow stratification of the blend in the manifold and relatively simple that is once you understand it Mechanical but electronic too As with just about everything else automotive K Jet didn t escaped change in the last decade When three way catalysis became necessary in ord
3. The control pressure is now solely controlled by the valve spring and maintained at its normal level The control pressure is about 0 5 bar at cold start and about 3 7 bar with the engine at operating temperature Auxiliary air device In order to overcome the increased friction in the cold state and to guarantee smooth idling the engine receives more air fuel mixture during the warm up phase due to the action of the auxiliary air device When the engine is cold the frictional resistances are higher than when it is at operating temperature These must also be overcome by the engine during idle For this reason the engine is allowed to draw in more air by means of the auxiliary air device which by passes the throttle valve Due to the fact that this auxiliary air is measured by the air flow sensor and taken into account for fuel metering the engine is provided with more air fuel mixture This results in idle stabilisation when the engine is cold In the auxiliary air device a perforated plate is pivoted by means of a bimetal spring and changes the open cross section of the bypass line Dependent upon temperature the plate assumes a given position so that in the case of a cold engine a correspondingly larger cross section of the bypass line is opened As the temperature increases the open area is decreased until finally it is closed completely The bimetal is heated electrically This means that the opening time can be limited according to engine type
4. Lambda closed loop control circuit By means of the Lambda closed loo control the air fuel ratio can be maintained precisely at Lambda 1 00 The Lambda closed loop control is an add on function which in principle can supplement every controllable f uel management system It is particularly suitable for use with Jetronic gasoline injection systems or Motronic Using the closed loop control circuit formed with the aid of the Lambda sensor deviations from a specified air fuel ratio can be detected and corrected This Control principle is based upon the measurement of the exhaust gas oxygen by the Lambda sensor The exhaust gas oxygen is a measure for the composition of the air fuel mixture supplied to the engine The Lambda sensor acts as a probe in the exhaust pipe and delivers the information as to whether the mixture is richer or leaner than Lambda 1 00 In case of a deviation from this Lambda 1 00 figure the voltage of the sensor output signal changes abruptly This pronounced change is evaluated by the ECU which is provided with a closed loop control circuit for this purpose The injection of fuel to the engine is controlled by the fuel management system in accordance with the information on the composition of the air fuel mixture received from the Lambda sensor This control is such that an air fuel ratio of Lambda 1 is achieved The sensor voltage is a measure for the correction of the fuel quantity in the air fuel mixture The signal which is pro
5. Mixture enrichment by means of control pressure reduction In those cases where engines are operated with a very lean mixture in the part load range an extra mixture enrichment must be provided at full load in addition to the mixture adaptation resulting from the shape of the air funnel This extra enrichment is carried out by a specially designed warm up regulator This regulates the control pressure depending upon the manifold pressure In this model of the warm up regulator two valve springs are used instead of one The outer of the two springs is supported on the housing as is the case with the normal model warm up regulator The inner spring though is supported on a diaphragm which divides the regulator into an upper and a lower chamber The manifold pressure is effective in the upper chamber which is connected to the intake manifold behind the throttle valve by means of a hose Depending upon the model the lower chamber is subjected to atmospheric pressure either directly or by means of a second hose leading to the air filter Due to the low manifold pressure in the idle and part load ranges which is also present in the upper chamber the diaphragm lifts to its upper stop The inner spring is now at maximum pretension The pretension of both springs as a result determines the particular control pressure for these two ranges When the throttle valve is opened further at full load the pressure in the intake manifold increases the diaphragm leaves
6. Technical Instruction series Mechanical systems With mechanical fuel injection systems one differentiates between those which require a drive from the engine and those which do not The engine driven systems comprise a fuel injection pump with an integrated governor Their principle of operation is the same as that of the fuel injection systems for Diesel engines The other variation of the mechanical system is one which needs no drive and which injects continuously This system the K Jetronic is described in the following The K Jetronic The K Jetronic is a mechanical fuel injection system from Bosch It is divided into three main functional areas e Air flow measurement e Fuel supply e Fuel induction Air flow measurement The amount of air sucked in by the engine is controlled by a throttle valve and measured by an air flow sensor Fuel supply An electrically driven fuel pump delivers the fuel to the fuel distributor via a fuel accumulator and a filter The fuel distributor allocates this fuel to the injection valves in the cylinder intake tubes Fuel induction The amount of air corresponding to the position of the throttle plate sucked in by the engine serves as the criteria for the metering of the fuel to the individual cylinders The amount of air sucked in by the engine is measured by the air flow sensor which in turn controls the fuel distributor The air f low sensor and the fuel distributor are assemblies which
7. The auxiliary air device is so located that it is heated up by the engine to the engine temperature This ensures that the auxiliary air device does not respond when the engine is warm Load conditions The adaptation or correction of the air fuel mixture to the operating conditions of idle part load and full load is carried out by means of appropriately shaping the air funnel in the air flow sensor If the funnel had a purely conical shape the result would be a mixture with a constant air fuel ratio throughout the whole of the sensor plate range of travel metering range As has already been mentioned though it is necessary to meter to the engine an air fuel mixture which is optimal for particular operating conditions such as idle part load and full load In practice this means a richer mixture at idle and full load and a leaner mixture in the part load range This adaptation is achieved by designing the air funnel so that it becomes wider in stages If the cone shape of the funnel is flatter than the basic cone shape which was specified for a particular mixture e g for Lambda 1 this results in a leaner mixture If the funnel walls are steeper than in the basic model the sensor plate is lifted further for the same air throughput more fuel is therefore metered and the mixture is richer Hence the funnel is so shaped that a richer mixture is produced at idle and full load and a leaner mixture at part load full load and idle enrichment
8. form Part of the mixture control unit Injection takes place continuously that is without regard to the position of the intake valve During the intake valve closed phase the fuel is stored in the intake tubes Fuel supply Outline of system The fuel is drawn out of the fuel thank by an electrically driven fuel pump It is then forced under pressure through a pressure accumulator and a fine filter to the fuel distributor which is located in the mixture control unit The pressure is held constant by a pressure regulator in the mixture control unit from where it flows to the fuel injection valves The injection valves inject fuel continuously into the intake ports of the engine cylinders The designation K Jetronic stems from his fact K stands for the German word for continuous When the intake valves open the air fuel mixture is drawn into the cylinders The individual subassemblies of the fuel supply system are described in the following Electric fuel pump The electric fuel pump is a roller cell pump the electric motor of which is permanently surrounded by fuel The fuel pump is driven by a permanent magnet electric motor The rotor disc which is eccentrically mounted in the pump housing is fitted with metal rollers in notches around its circumference which are pressed against the thrust ring of the pump housing by centrifugal force and act as seals The fuel is carried in the cavities which form between the rollers The fuel flows di
9. fuel pressure regulator The fuel pressure regulator restricts the return of fuel to the tank by a calibrated amount maintaining system pressure at the desired level On early K Jet systems this regulator was a slide valve also known as a push valve internal to the fuel distributor Fuel pressure could be adjusted by adding or removing shims from the valve On later K Jet systems the regulator is the conventional diaphragm type Control pressure or counter pressure is the pressure that is metered to the top of the fuel plunger on a K Jet system By changing the counter pressure the resistance to plunger movement is changed allowing enrichment and enleanment of the fuel mixture to the engine On a car equipped with K Jet this pressure is controlled by the warm up regulator The warm up regulator only compensates for engine temperature and is therefore a rather coarse control of fuel mixture Some K Jet warm up regulators also have a vacuum port to help with the acceleration enrichment and deceleration enleanment function Typical control pressures on a K Jet warm up regulator are 55 psi with the engine at full operating temperature and 20 to 30 psi on a cold engine The colder the engine the lower the pressure A car equipped with K Jet Lambda also changes control pressure with a warm up regulator with pressures similar to a plain K Jet system but also controls lower chamber pressure in the fuel distributor by bleeding pressure
10. is injected by the start valve into the intake manifold The injection period of the start valve is limited by a thermo time switch depending upon the engine temperature This process is known as cold start enrichment and results in a richer air fuel mixture i e the excess air factor is temporarily less than 1 Start valve The start valve is of the solenoid operated type The winding of an electromagnet is fitted inside the valve In the inoperated state the movable armature of the electromagnet is forced against a seal by means of a spring and thus closes the valve When the electromagnet is energised the armature which as a result has lifted from the valve seat opens the passage for the flow of fuel through the valve From here the fuel enters a special nozzle at a tangent and is caused to rotate The fuel is particularly well atomised by this specially shaped nozzle the so called swirl nozzle and enriches the air in the intake manifold downstream of the throttle valve with fuel Thermo time switch The thermo time switch limits the injection period of the start valve dependent upon engine temperature It is comprised of an electrically heated bimetal strip which depending upon its temperature either opens or closes an electric contact The complete device is fitted into a hollow threaded pin which in turn is located at a position where typical engine temperature prevails The thermo time switch determines the injection period of the
11. lifetime filter mounted on the same bracket as the pump and accumulator the flow reaches the fuel distributor and here s where you ll find the main differences between KE and other CIS s As you know if you read the previous section the basic principle of Bosch continuous injection is that a metal disc floating in a cone moves in accordance with the amount of air entering the engine and the disc s lever is connected to a control plunger that rises in a barrel progressively uncovering fuel metering slits The more air being taken in the more the disc moves and the more gasoline is delivered This much remains the same Mixmaster Differential pressure valves still serve to maintain the pressure drop at the metering slits regardless of how much fuel is flowing through them and here s where KE s closed loop mix control comes in An electro magnetic differential pressure regulator a small plastic box screwed to the side of the fuel distributor its presence will let you know the system is KE opens and closes as commanded by the ECU varying pressure in the lower chamber of the fuel distributor When the computer gets a lean signal from the oxygen sensor it sends additional current to the pressure regulator increasing differential pressure hence fuel flow so the blend richens And vice versa Although the whole differential pressure versus fuel flow concept 1s a little hard to grasp what I ve just said is really all you need to know for di
12. slowly lift the plate between and Ys in Observe the injector spray pattern If the pattern ia good reinstall the injectors and test drive If the pattern is bad replace the injectors A ied Fe Done am Im E Internet A EI How to Tune and Modify Bosch Fuel Injection Google Book Search Microsoft Internet Explorer File Edit view Favorites Tools Help da Back gt fx Mi EA Search 3g Favorites ir Media A Eh E Address http boaks gaogle com baokszideuuT AwfFOYOEC amp pg PA1568lpg PA1568dg air FFlewir GG temperature sensitive resistor called a thermistor As the coolant temperature increases the resist ance of the drops The com reases the current to the pressure actuator when the engine i d and slowly decreases it as the engine warma up Addi tionally this is used to signal the system computer tha le speed needs to be higher to compensate for cold engine operation Throtile Switch The throttle switch is tero contact switch One set af contacts is closed when the throttle is closed The other set is closed when the throttle is wide open Lambda The CI ystem uses a Lambda to rmon itor exhaust gasea When a lean ase is detected the Lambda sends a low voltage less than 0 5 volt to A em computer The computer responds by increasing the current through the electrohvdraulic actuator whic creases the lower chamber pressure and enriches the mixture When the engine begin
13. terminal 1 of the ignition coil These pulses are processed by an electronic circuit in the control relay which switches on after the first pulse and applies voltage to the electric fuel pump the auxiliary air device and the warm up regulator The control relay remains switched on as long as the ignition is switched on and the engine is running If the pulses from terminal 1 of the ignition coil stop because the engine has stopped turning for instance in the case of an accident the control relay switches off about 1 second after the last pulse is received This safety circuit prevents the fuel pump from pumping fuel when the ignition is switched on but the engine is not turning Exhaust gas techniques Exhaust gas composition Fuel combustion in the engine working cylinder is more or less incomplete The less complete the combustion the higher is the emission of toxic substances in the exhaust gas Perfect or total combustion of the fuel is impossible even when surplus air is available in plenty In order to reduce the load on the environment it is imperative that engine exhaust gas emissions are reduced drastically All measures taken to reduce the toxic emissions in compliance with a variety of legal requirements aim at achieving as clean an exhaust gas as possible while at the same time featuring optimum fuel economy figures excellent drive ability high mileage figures and low installation costs In addition to a large percentage of harml
14. the CO adjustment as previoualy described Lenking Injectors Remove the injectors from the cylinder head Energize the fuel pump and watch the injector tips for evidence of dripping If a drop forms falls from the tip of the injector amd is replaced by another drop replace the offending injectar Leaking Cold Sari Imector Remove the cold start injector from the cylinder head Energize the fuel pump and watch the tip for evidence of dripping If a drop formas falls from the tip of the cold start injector and is replaced by another drop replace tt What to Do and When Lack of Fuel Pressure When there is no fuel pressure the first thing to do is confirm that there is fuel in the tank I have seen several methods at various levels af sophis Licatron to confirm fuel quantity Of all these methods the best and simplest is to pour a gallon or ac of fuel into the tank If there is an adequate amount of fuel in the tank the next item of business is to confirm fuel pump operation Place mechanics stethoscope on the fuel pump and have somecne crank the engine If Lhe fuel pump is located inside the fuel tank then place the stethoscope on the fuel tank As the engine 15 cranked the hum of the fuel purnp should be heard through the stethescope If no hum is heard check electrical power to the pump Begin by inspecting the fuel pump fuse If the fuel pump fuse i8 gord connect the alligator clip of a test light to the ground side o
15. the stops in the spring chamber The diaphragm remains in this position which corresponds to the maximum accumulator volume as long as the engine is running Fuel filter Due to the extremely close tolerances of various components in the system it is necessary to fit a special fine filter for the fuel in order to guarantee faultless performance of the K Jetronic The fuel filter retains particles of dirt which are present in the fuel and which would otherwise adversely affect the functioning of the injection system The fuel filter contains a paper filter element which is backed up by a strainer This combination results in a high degree of cleaning being achieved A supporting plate is used to hold the filtering elements in place in the filter housing It is of utmost importance that the direction of flow indicated on the housing is complied with The filter is fitted in the fuel line downstream of the fuel accumulator Primary pressure regulator The primary pressure regulator maintains the pressure in the fuel system constant The pressure regulator incorporated in the fuel distributor housing maintains the delivery pressure primary pressure at about 5 bar Due to the fact that the fuel pump delivers more fuel than the engine needs a plunger shifts in the pressure regulator and opens a port through which excess fuel can return to the fuel tank The pressure in the fuel system and the force exerted by the spring on the plunger in the pressure
16. 0742413 0000742513 0000742713 0000742813 0438101003 0438101004 0438101011 0438101012 0438101025 0438101026 0438101027 0438101028 0438101017 0438101018 0438101015 0438101016 0438101009 0438101010 0438101043 0438101044 190E to 1986 190E 2 6 260E 300E 300SE 300SEL 300TE 190E from 1987 190E 16V 420SEL 560SEC 560SEL 560SL 500SL to 1992 190E 16V European version 300CE 300SL 1990 92 German Star Mercedes Benz Fuel Distributors 162B2 N Cerro Alto Dr Fountain Hills AZ 85268 Toll Free 800 377 6598 Local Phone 480 836 4515 Fax 480 837 2886 Email sales germanstar net E Fuel Distributor Microsoft Internet Ex Lols 395 00 465 00 395 00 495 00 495 00 495 00 495 00 465 00 1993 95 Chrysler Concord New Yorker LHS Dodge Intrepid and Eagle Vision The K Series fuel injection systems are continuous mechanical fuel injection systems used on a wide variety of European vehicles including such makes as Volkswagon Audi BMW Mercedes Porsche Volvo and Saab The system is one of the most common fuel injection systems on the market today but also is one of the least understood The K Jetronic System constantly injects fuel into the engine as long as the car is running and air flow is present to move the sensor plate in the airflow sensor The sensor plate is connected to an arm that pushes up on a plunger located in the fuel distributor As air
17. 46 0438100068 0438100089 0438100041 0438100086 0438100054 0438100069 0438100011 0438100036 0438100084 0438100071 0438100091 0438100040 0438100085 0438100099 0438100106 0438100087 0438100088 0438100111 0438100112 0438101002 We carry a complete line of remanufactured fuel distributors covering applications for all Mercedes Benz vehicles including both U S and European versions Y Each Mercedes Benz fuel m distributor carries a full 12 ye month warranty A AM 1 s refundable 100 core charge applies to each unit Fuel Ji distributors for all other European cars are also available Mercedes Benz Fuel Distributor Application Notes 450SE 450SEL 450SL 450SLC to 1979 450SE 450SEL 450SL 450SLC from 1980 280CE 280E 280SE 280SEL 280SL 280SLC European version 280CE 280E 280SE 1977 79 230CE 230E 230GE 230TE European version 280CE 280E 280SE from 1980 380SE 308SEC 380SEL 380SL 380SLC 500SEC SOOSEL 380SE 380SEC 380SEL 380SL 380SLC 500SE 500SEC 500SEL 500SL European version 190E 230E 230TE European version Mercedes Benz Fuel Distributors 4G Pa x wr F mi Ti b r f CUM F a ffi Call 800 377 6598 or Order Here 2 B H a e Tt e Price 465 00 495 00 495 00 465 00 425 00 465 00 465 00 495 00 425 00 0000741513 0000741913 0000742013 0000742313 000
18. Bosch K Jetronic Fuel Injection Part 1 The Engine s Fuel Requirements A spark ignition engine needs a particular air fuel ratio in order to operate The ideal air fuel ratio is 14 7 1 Certain operating conditions make it necessary to correct the mixture accordingly The air fuel ratio Essentially the power the fuel consumption and the exhaust gas composition of a spark ignition engine depend upon the air fuel ratio Perfect ignition and perfect combustion only take place within particular air fuel ratios In the case of gasoline petrol the ideal air fuel ratio is about 15 1 In other words 15 kg of air are required for complete combustion of 1 kg of gasoline stoichiometric ratio Deviations from this ratio affect engine operation The amount of fuel to be injected depends upon load engine speed and the particular exhaust gas regulations in force at the time Depending upon the mode of operation i e idle part load or full load a different air fuel ratio is optimal in each case Of decisive importance is the strict adherence to the particular most favourable air fuel ratio at any one time The excess air factor The excess air factor is identified by the symbol for Lambda Lambda amount of air supplied theoretical air requirement Lambda 1 This means that the amount of air supplied to the engine corresponds to the theoretical amount of air required stoichiometric air fuel ratio Lambda lt 1 This means air deficie
19. agnosis The injectors themselves by the way are of the air shrouded variety that provide a very finely atomized spray Air flow through passages in the cylinder head really breaks up those droplets Instead of the combo of a control pressure regulator and a pressure relief valve KE Jet has only a diaphragm type pressure regulator which maintains about 78 psi in the system by venting the excess back to the tank and also keeps residual pressure available after the engine s shut down A cold start valve sprays extra gas into the intake manifold when it gets voltage from the thermo time switch just like previous systems Also similar is the auxiliary air regulator which is plumbed across the throttle plate to let in extra air for fast idle With that operational explanation taken care of I ll look at service As with every other modern engine control or fuel injection system don t assume a driveability or performance problem is due to KE Jet until you ve checked for ignition problems vacuum leaks poor compression etc If it s not tampered with this set up should stay in calibration and last just about forever But that s not to say you ll never run into any problems with it Closed loop The first thing to find out is 1f the closed loop mode is ever being entered and for that you ll need a milli amp meter and either a special VW wiring adapter I d be surprised if you bought such a thing or some home made leads With the ignition o
20. air fuel ratio A lean ratio can result in a backfire under load or when starting Check for Vacuum Leaks Vacuum leaks can result in lean mixture and a lean mixture can result in a backfire One of the best techniques for locating a vacuum leak is to run a little propane around the intake system Engine Misfires under Load fgnation Problems The most likely cause of a misfire is always the ignition system regardless of the fuel ayaterm Inadequate Fuel Delivery engine running lean An insufficient supply of fuel ean be the result af a binding airflaw sensor or contro plunger re stricted injectors incorrect contro or aystem pres sure Ales perform an equal flow and apray pattern test on the impactore Poor Power Incorrect Tune Up Specs or Worn Tume Up Ports As with a carbureted engine the most likely cause of poor power is the basic tune up specifications of timing dwell and air fuel ratio Also worn diatribu tor caps spark plugs points and plug wires can seriously impact the performance of the K Jetronic with Lambda engine Contro Pressure Tho High High control pressure will limit the travel of the control plunger thereby limiting the amount of fuel that can flow into the engine When the engine begins to run lean power can suffer Restricted Injgctors Restricted injectors can limit the amount of fuel that can pass through them thereby limiting power Stumble or Sag on Acceleration Sucking or Binding Ai
21. alog systems are D jetronic manufactured from about 1969 to 1974 gt gt L jetronic 1974 to mid 80 s most LE jetronic 1981 to early 90 s and gt gt all LU jetronic the same as LE but with closed loop lambda control gt gt gt gt Digital systems are LH jetronic from early 80 s to mid 90 s most of gt gt them but not all have closed loop LH 2 4 and later have adaptive lambda gt gt correction and some diagnostic features LE3 jetronic the last gt gt non closed loop system the ecu is integrated in the air flow meter and gt gt Mono jetronic a TBI system only used with closed loop and adaptive gt gt lambda correction gt gt gt gt The K jetronic an all mechanical system should also be mentioned It gt gt may have a closed loop add on and is then called K lambda jetronic A gt gt Similar but newer variant is called KE jetronic it exists both without gt gt and with closed loop Most KE systems are analog but the KE3 is digital gt gt and then uses an ecu that is very similar to the Mono jetronic ecu gt gt gt gt Most digital Jetronic systems use an Intel MCS 51 CPU Either a standard gt gt 8051 8031 with a separate A D converter or an 80535 80C535 In some gt gt cases mask programmed 8051 s may be found but they more commonly have gt gt an external eprom Anyway all PCBs are designed for external eprom so gt gt it is a simpl
22. ator problems are extended crank time and hard start hot With an understanding of the system and the proper tools K Jetronic fuel system service is a straightforward procedure that can keep your service bays full all year long Give me a call if you have any questions File Edit iaa To Favorites Help 3 http rb k bosch de resources literatur leseproben uz13e pdf Microsoft Internet Explorer do Back wb fx fat Gh Search GJ Favorites eMedia cS Eh a E Attachments Comment p Gasoline injection systems Vg eee Adder Here the evaluated sensor signals are combined The electrically processed comective signals are added in an operational circuit and then transmitted to the current regulator Output stage The output stage generates the control signal for the pressure actuator whereby it is possible to input opposing currents into the pressure actuator in order to increase or decrease the pressure drop The magnitude of the current in the pressure actuator can be adjusted at will in the positive direction by means of a permanently triggered transistor The current is reversed during overrun overrun fuel cutoff and influences the differential pressure at the differential pressure valves so that the flow of fuel to the injection valves is interrupted Additional output stages If necessary additional output stages can be included These can trigger the valves for EGR and
23. ce the differential pressure regulator If the resistance reading is correct check the ECU power and grounds Also check the ground for the temperature If these are OK replace the ECL Test Rest Pressure Rest or residual pressure is a measurement of the KE syetem ability to retain pressure after the engine has been shut off Open the valve on the L57 10 x d Page 157 yr CI Exit full screen E Deme am mi m F Internet a EI How to Tune and Modify Bosch Fuel Injection Google Book Search Microsoft Internet Explorer File Edit wiew Favorites Tools Help da Back E fat Se Address amp httosiibooks google com books id uuT_AwfOYOECEpg P4156epg PA1 56 amp dq air flaw Y SSL MURE and energie thi fuel purnip far about thirty seconda Shut eff the Fuel purnup and monitor the pressure for ten minutes The pres sure should not drop below psi If the pressure dreps too low remove the differential pressure regulator electrohydraulic actuator and inspect the O rings If the O rings are functioning prop erly or the pressure continues to drop when the test ie repeated after replacement pinch off the svatem pressure regulator return line Repeat the teat If the pressure holds replace the system pressure regulator If the pressure still falla re place the electrohydraulic actuator Check Pre pump Delivery Volume Some KE injection systems use a pre piummp When the symptoms include sagging hesitat
24. cessed in the closed loop control circuit is used to control the actuators of the Jetronic installation In the fuel management system of the K Jetronic or carburettor system the closed loop control of the mixture takes place by means of an additional control unit and an electromechanical actuator frequency valve In this manner the fuel can be metered so precisely that depending upon load and engine speed the air fuel ratio is an optimum in all operating modes Tolerances and the ageing of the engine have no effect whatsoever At values above Lambda 1 00 more fuel is metered to the engine and at values below Lambda 1 00 less This continuous almost lag free adjustment of the air fuel mixture to Lambda 1 00 is one of the prerequisites for the efficient after treatment of the exhaust gases by the downstream catalytic converter Control functions at various operating modes Start The Lambda sensor must have reached a temperature of above 350 C before it outputs a reliable signal Until this temperature has been reached the closed loop mode is suppressed and the air fuel mixture is maintained at a mean level by means of an open loop control Starting enrichment is by means of appropriate components similar to the Jetronic installations not equipped with Lambda control Acceleration and full load WOT The enrichment during acceleration can take place by way of the closed loop control unit At full load it may be necessary for temperat
25. control the bypass cross section around the throttle valve as Fig 20 EE UEg Me DW required for idle mixture control to mention but two applications Electro hydraulic pressure actuator Depending upon the operating mode of the engine and the resulting current sig nal received from the ECU the electro hydraulic pressure actuator varies the pressure in the lower chambers of the differential pressure valves This changes the amount of fuel delivered to the injection valves Design The electro hydraulic pressure actuator Figure 20 is mounted on the fuel distri butor The actuator is a differential pressure controller which functions according to the nozzle baffle plate principle and its pressure drop is con trolled by the current input from the ECU In a housing of non magnetic material an armature is suspended on a fric tionless taut band suspension element between two double magnetic poles The armature is in the form of a dia phragm plate made from resilient material Electro hydraulic pressure actuator fitted to the fuel distributor The control signal from the ECL intervenes im the position of the baffle plate 11 This in turn varies the fuel pressure in the upper chamber of the differential pressure valves and as a result the quantity of fuel delivered to the injection valves injectors Using this principle adaptation and comection functions can be incorporated Sensor plate Fue distributo
26. e task to solder an eprom socket and the address latch in gt gt place and change the jumper for the CPU s EA signal gt gt The eprom may be socketed or soldered in place depending on requirements gt gt from each car manufacturer gt 2 gt gt Some older LH jetronic in particular LH 2 2 use instead an 8049 CPU gt gt The very earliest LH systems might have an RCA 1802 like the early gt gt Motronic systems gt gt gt gt The simplest way to identify a Jetronic system is to look at the Bosch gt gt part number of the ECU gt gt I e 0 280 000 561 The first six digits tell just that it is a Jetronic gt gt CPU The seventh digit indicates the number of cylinders 0 means 4 gt gt cylinders 1 means 6 cylinders and 2 means 8 cylinders The eighth digit indicates the variant 0 means D jetronic 1 and 2 means L Jetronic 3 gt gt means LE and LU jetronic 5 and 9 means LH jetronic 7 means gt gt Mono jetronic and 8 means K lambda and KE The two last digits are a leap number So when asking about a Jetronic system be sure to include the variant of the system I e mention that you have an LH 2 4 with closed loop Best regards Torbjorn Forsman V V V V V V V V V VM V V V V V V V V V V V Part 0000740313 0000740413 0000740713 0000740813 0000740913 0000741013 0000741113 0000741313 0000741413 Bosch 0438100012 04381000
27. el pump by removing the pump s electrical relay and bridging panel terminals 30 and 87 for about five seconds then try to lift the sensor plate using a magnet on its 10 mm center bolt You should feel somewhere between just noticeable clearance and 080 1n that s 5 64 in or 2mm of movement While you re there you might as well raise the plate through its full range to find out if it s binding which condition can be corrected by loosening the bolt centering the plate so a 004 in feeler gauge can go all the way around it and retightening the bolt four ft Ibs will do and thread locking compound is a good idea here Coping with cold When you encounter a hard or no start while cold problem think about the thermo time switch and the cold start valve The points in the switch open at 86 degrees F so make sure the engine s below that temperature then remove the connector from the cold start valve ground terminal Z4 of the 1gnition coil and put a test light across the connector s terminals Run the starter and the light should glow for between one and eight seconds then wink out To test the fuel delivery of the valve itself remove the two Allen head screws that hold it to the intake manifold detach the valve and aim its business end into a suitable container energize the fuel pump as explained above then connect a jumper from the positive battery post to one of the valve s terminals and another jumper to ground be careful n
28. el lines or at the accurmualator dammed or Sticking Airflow Sensor After removing the airflow sensor boot inspect for proper adjustment of the sensor plate Adjust as necessary If the adjustment is OK the binding is at the fulerum the only component of the K sye tem with Lambda that can be disassembled and reassembled without damaging it Remove the airflow sensor assembly from the car On each side of the sensor you will find a disc held in place by an internal snap ring Remove the nap rings and with a small screwdriver wobble the disc back and forth until it falls out There is a large counterweight on the end of the airflow sensor lever loosen the large screw that holds the counterweight in place At the same time this will loosen the fuler m shaft Carefully mount the airflow sensor assembly in a vise and using a brass drift drive the shaft aut of the assembly Wash all of the metal components in solvent removing any varnish build up that may have occurred over the vearsa Rinse the solvent off of Lhe parts with hot water The hot water will evaporate quickly reducing the possibility of rusting Reassemble the airflow sensor using a very light film of point lube or similar lubricant Make the sensor plate adjustments and reinstall on the car Auxiliary Air Valve Not Opening There is really nothing that can be done for an auxiliary air valve that does not open short of replacement Verify that the valve is not receivin
29. er to meet NOx limits a means of keeping the air fuel mix closer to the ideal stoichiometric ratio that is 14 7 1 air to fuel by weight than could possibly be achieved mechanically was needed So this injection set up got add on electronics to give closed loop operation and satisfy the Feds First this was called K Jetronic with Lambda that Greek letter has come to represent the stoichiometric blend but later came a more elegantly simple version KE Jetronic You ll find it on several Volkswagen and Audi models from 84 up even the entry level Fox a neat little car that in our opinion outclassed its competition Since VW has made more vehicles with this system which the company calls CIS E for Continuous Injection System Electronic than everybody else put together I ll give you the gospel according to Wolfsburg and use the Fox as my example Although I m being very model specific here a lot of what I say will give you a better understanding of K Jetronic in general Flow The little Volks has a fuel supply system with a small in tank transfer pump that sends gasoline up to a reservoir From there the main roller cell electric pump which should never be allowed to run dry picks it up and pushes it into an accumulator which protects the metal diaphragm in the fuel distributor from the shock of the pump turning on and maintains residual pressure after the engine 1s shut down to help avoid vapor lock After passing though a big
30. ess substances the exhaust gas of a spark ignition engine contains components which are harmful to the environment when they occur in high concentrations About 1 of the exhaust gas is harmful and consists of carbon monoxide CO oxides of nitrogen NOx and hydrocarbons HC The major problem in this respect is the fact that although these three toxic substances are dependent upon the air fuel ratio when the concentration of CO and HC increases the concentration of NOx decreases and vice versa Carbon monoxide Carbon monoxide CO reduces the ability of the blood to absorb oxygen and as a result lowers the blood oxygen content This fact together with it also being colourless odourless and tasteless makes CO extremely dangerous Even as low a proportion as 0 3 percent by volume of CO in the air can prove fatal within 30 minutes For this reason it is forbidden to run an IC engine inside closed rooms or halls without the extraction system being in operation Oxides of nitrogen Oxides of nitrogen NOx are also colourless odourless and tasteless but in the presence of atmospheric oxygen they rapidly convert to reddish brown nitrogen dioxide NO2 which smells pungently and causes pronounced irritation of the respiratory system Due to the fact that NO2 destroys the lung tissue it is also detrimental to health when encountered in higher concentrations NO and NO2 are usually referred to together as NOx Hydrocarbons A wide varie
31. estriction dampens a possible oscillation of the sensor plate which could result due to pulsating air intake flow The control pressure influences the fuel distribution If the control pressure is low the air drawn in by the engine can deflect the sensor plate further This results in the control plunger opening the metering slits further and the engine being allocated more fuel On the other hand if the control pressure is high the air drawn in by the engine cannot deflect the sensor plate so far and as a result the engine receives less fuel In order to fully seal off the control pressure circuit with absolute certainty when the engine has been switched off and at the same time to maintain the pressure in the fuel circuit the return line of the warm up regulator is fitted with a non return valve This push up valve is actually in the primary pressure regulator and is held open during operation by the pressure regulator plunger When the engine is switched off and the plunger of the primary pressure regulator returns to its zero position the non return valve is closed by a spring Differential pressure valves The differential pressure valves in the fuel distributor serve to hold the drop in pressure at the metering slits constant The air flow sensor has a linear characteristic This means that if double the quantity of air is drawn in the sensor plate travel is also doubled If this linear travel is to result in a change of delivered fuel i
32. f the fuel pump connector and probe the pesitive side of the fuel pump connector If the test light goes on then the pump is receiving power and has a good ground If the test light fails to light up connect the alligator 145 E Page 145 a C Exit full screen TT E i Done m am um Internet E How to Tune and Modify Bosch Fuel Injection Google Book Search Microsoft Internet Explor Bl xl File Edit View Favorites Tools Help Bak gt amp at search Favorites Media E4 ET CQ Gi clip to a good chassis ground and probe the positive terminal on the fuel pump If the test light still fails to light up check the fuel pump relay and inspect the fuel pump wiring harness If the test light finally goes on inspect the fuel pump ground Another reason for a lack of fuel pressure is restriction im the fuel lines or the fuel filter Energize the fuel pump and begin loosening fit tings along the fuel supply line USE EXTREME CAUTION THOUGH AS THE FUEL WILL BE UNDER AS MUCH AS 100 PSI PRESSURE AND WILL TEND TO SPRAY OUT IN A FIME HIGHLY FLAMMABLE MIST If there is only a small amount of pressure or volume present at a loosened fitting inspect the components upstream of that fitting for restric tions Restrictions are comtmoenly found in the fuel filter and the in tank pickup filter screen An obvious reason for ne fuel pressure would he an external leak Look for external leaks anywhere along the fu
33. ff unplug the two terminal connector from the differential pressure regulator Those Bosch plugs can be difficult 1f you re not used to them pry off the metal clip completely with a small screwdriver then separate the connection Using very narrow spade terminals crimp a male to one end of a six inch wire and a female to the other Attach a similar pair of spades to the leads of your meter I found that an ordinary analog multi meter worked fine Since a short here can blow the electronics I wrapped the spades with electrical tape to make sure they wouldn t make contact with each other Now connect the male end of your jumper to one side of the plug the female end to the corresponding spade of the differential pressure regulator then attach your meter in series across the other terminals and set it to the milli amp scale Start the engine let it get warm and make sure all electrical accessories are off Once normal operating temp is reached remember any oxygen sensor has to be warm to work so you may need to hold rpm at 2 500 or so for a while to heat it up look for a reading of 10 mA or 6 and it should fluctuate over a 1 3 milli amp range That fluctuation is the tip off that closed loop operation 1s occurring in open loop the ECU sends a fixed 10mA signal which won t cause any drivability problems but will increase emissions A CO test should ideally go along with this If you happen to access to an exhaust analyzer
34. flow changes the movement of the sensor plate and the plunger increase and decrease the volume of fuel injected into the engine Since fuel is being injected constantly fuel pressure will have a direct affect on driveability As a matter of fact fuel pressure is the single most critical element when diagnosing driveability problems in the K Series fuel injection systems An accurate fuel pressure gauge must be used when testing these systems with a range of 0 to more than 100 psi You will also need a digital volt ohm meter DVOM that can read milliamps You will work with three types of pressures when diagnosing these systems system pressure control pressure also known as counter pressure and rest pressure System pressure is the total fuel pressure produced by the fuel pump on a constant basis The fuel pump must be able to maintain this pressure during all driving conditions from idle to wide open throttle As a rule system pressure will run about 5 to 5 5 bar pressure or 75 to 85 psi 1 bar about 15 psi and the pump should be able to produce a minimum volume of 1 pint in 15 seconds When deadheaded the K Series fuel pump will produce about 1 5 times the system pressure or about 110 to 120 psi System pressure is a function of volume of fluid moved against a restriction so to maintain system pressure at the desired level there must be some type of restriction built into the fuel system This restriction is more commonly known as the
35. g power all the time and replace it Cold Start Injector Not Opening The cold start injector is a simple normally closed solenoid operated valve If the cold start injector does not open when the engine tempera ture is below 95 deg E disconnect the cold start 146 i Panes 147 174 are nnt nar nf this hook nrevigw L T Page 145 rs C Exit full screen Injector and connect a test light across the bermi nals Crank the engine If the test light goes on the wiring harness ia good Loosen the fuel line at the cold start injector and crank the engine again If fuel leaks or sprays from the loosened Hine replace the cold start injector If not confirm fuel delivery to the fuel distributor and repair or replace the restricted fuel line If the fuel line delivers fuel then replace the cold start injector If connecting the test light across the terminals and cranking the engine does not light the test light confirm that the engine temperature is below 95 deg F Connect the test light alligator clip to the positive battery terminal and probe the harness connector of the cald start injector One of the two lerminals should activate the test light the other should not If neither activatea the test light inspect the wire that runs from the cold atart injector to the thermo time awitch If this is gond inspect the one that runs from the switch to ground for an open circuit lf both wires teat aatiafactaorily replace the the
36. he valve cross section at the outlet line until the differential pressure of 0 1 bar is again present This causes an equilibrium of forces to prevail at the diaphragm which can be maintained for every quantity of fuel by controlling the valve cross section Mixture formation The formation of the air fuel mixture takes place in the intake manifold tubes and cylinders of the engine The continually injected fuel coming from the injection valves is stored in front of the intake valves When the intake valve is opened the air drawn in by the engine carries the waiting cloud of fuel with it into the cylinder An ignitable air fuel mixture is formed during the induction stroke due to the swirl effect Mixture Adaptation In addition to the basic functions described up to now the mixture has to be adapted during particular operating conditions These adaptations corrections are necessary in order to optimise the power delivered to improve the exhaust gas composition and to improve the starting behaviour and driveability Cold start Depending upon the engine temperature the start valve injects extra fuel into the intake manifold for a limited period during the starting process During cold starting part of the fuel in the mixture drawn in is lost due to condensation on the cold cylinder walls In order to compensate for this loss and to facilitate starting the cold engine extra fuel must be injected at the instant of start up This extra fuel
37. highly precise adjustment you need only ensure that the top of the rests just below the top edge of the of the venturi If the adjust ment is incorrect open or close the wire clip around the leaf spring just below the m Er Free Play The justment to i the distance between the control plunger and the roller on the airflow ever Before checking this the ba M i ment must be correct Conne ammeter in series with the elertrohydraulic actuator Werify that the current is between 4 and 16 milliamps If the current is less than 4 milliamps allow the engine to wol down before continuing If the current is greater than 16 muillinmps warm the engine before continuing Crank the engine for ten seconds to build up fuel pressure Lift the until some resist ance is felt There should e free play but no more than HOFS in If this adjustment ia mol correct remove the fuel distributor and verify the basic lever adjustment If this adjustment is corr just the control plunger AChE Potentiometer Att rifying the atment airflow center rest position and f airtiow Airflow basic lev Ing i entiometer adjustment can be made toa high unpedance voltmeter to poten tiometer terminal number 17 With the pigs in the rest position the voltage should On Vlksmagnen s Audi procaeets trie fap stc af e rrj should remi ODR in brio dee upper edge af af tart of the oenturi 156 to 0 3 velt As o ig lifted the vol
38. inder leakage test Check the valve adjustment and camshaft condition Then verify the condition af the ignition avstem If all of these teat satisfactorily then check the injection system Test Fuel Pressure As in all fuel injection aystems any thorough system test must begin with fuel pressure Con nect a pressure gauge between the cold start valve and the port an the lower chambers of the fuel distributor Disconnect the electrical connector on the electrohydraulic actuator Then activate the fuel pump The pressure indicated should be he tween 75 and BZ psi If the pressure is low check the fuel pump volume The pump should be able to deliver 0 5 gpm gallons per minute or more If the volume is low check the fuel filter including the one in the tank and the line for kinks If the pressure is low but the volume is acceptable replace the system pressure regulator Ifthe fuel pressure is high disconnect the return line from the system pressure regulator and repeat the test Ensure that the fuel from the regulator ia captured in an approved fuel container If the fuel pressure remains high replace the pressure regu lator If the pressure drops elean or repair the return line The next step is to measure lower chamber dif ferential pressure or the difference between the pressure in the lower chambers of the fuel distribu tor amd system pressure This measurement is done in two steps The first step is to simulate press
39. ion or stumbling the delivery rate of this pump should be checked The minimum flow rate is about one pint in twelve seconds Check Main Pump Delivery Volume Main pump delivery volume should be approx imately 0 5 grtn GG Test Injectors for Equal Flow The injector qual flow test i5 an effort to deter mine how much contamination or restriction there is in the injectors Remove the injectors from the intake manifold leaving them attached to the fuel lines Place the nozzle of each injector in a gradu ated cylinder energize the fuel pump Lift the airflow sensor plate B an place the tip of a screw driver under the edge of the pb low the injectors for about thirty seconds then pul screwdriver out The volume of fuel that flowed through each injector should vary by only 10 percent Replace any injector that flowed 10 percent leas than the others if all injectors pass this test repeat the test with the airflow senaor plate lifted about 94 in Again the qua nek 1at flowed through each injector should be within 10 percent af each other If any injector flows 10 percent less than the rest replace the injector iol x Ai Fage 158 yr Exit full screen aie e Done imi I m Internet F gt gt It is not very precise to call an injection system Jetronic This is a gt gt brand name that Bosch uses for all systems that only deal with fuel gt gt injection not ignition gt gt gt gt An
40. ired fuel quantity it does not monitor the results Here one speaks of an open control loop The closed loop control of the mixture on the other hand measures the composition of the exhaust gas and uses the results to correct the calculated injected fuel quantity This is referred to as a closed control loop This form of control is particularly effective on fuel injection engines because they do not have the additional delay times resulting from the long intake paths typical of carburettor engines Lambda closed loop control Lambda sensor The Lambda sensor inputs a voltage signal to the ECU which represents the instantaneous composition of the air fuel mixture The Lambda sensor is installed in the engine exhaust manifold at a point which maintains the necessary temperature for the correct functioning of the sensor over the complete operating range of the engine Operation The sensor protrudes into the exhaust gas stream and is designed so that the outer electrode is surrounded by exhaust gas and the inner electrode is connected to the atmospheric air Basically the sensor is constructed from an element of special ceramic the surface of which is coated with microporous platinum electrodes The operation of the sensor is based upon the fact that ceramic material is porous and permits diffusion of the oxygen present in the air solid electrolyte At higher temperatures it becomes conductive and if the oxygen concentration on one side of the e
41. lectrode is different to that on the other then a voltage is generated between the electrodes In the area of stoichiometric air fuel mixture Lambda 1 00 a jump takes place in the sensor voltage output curve This voltage represents the measured signal Construction The ceramic sensor body is held in a threaded mounting and provided with a protective tube and electrical connections The surface of the sensor ceramic body has a microporous platinum layer which on the one side decisively influences the sensor characteristic while on the other serving as an electrical contact A highly adhesive and highly porous ceramic coating has been applied over the platinum layer at the end of the ceramic body that is exposed to the exhaust gas This protective layer prevents the solid particles in the exhaust gas from eroding the platinum layer A protective metal sleeve is fitted over the sensor on the electrical connection end and crimped to the sensor housing This sleeve is provided with a bore to ensure pressure compensation in the sensor interior and also serves as the support for the disc spring The connection lead is crimped to the contact element and is led through an insulating sleeve to the outside of the sensor In order to keep combustion deposits in the exhaust gas away from the ceramic body the end of the exhaust sensor which protrudes into the exhaust gas flow is protected by a special tube having slots so designed that the exhaust gas and the s
42. less substances The three way catalytic converter has come into widespread use here the term 3 way means that all three toxic substances CO HC and NOx are degraded at the same time The converter shell contains a ceramic honeycomb which is coated with a precious metal preferably with platinum and rhodium When the exhaust gas flows through this honeycomb the platinum and rhodium accelerate the chemical degradation of the toxic substances Only lead free gasoline may be used with such converters because the lead otherwise destroys the catalytic properties of the noble metal catalyst This means that lead free gasoline is a prerequisite for the employment of catalytic converters The catalytic conversion principle presupposes that the engine burns an optimum air fuel mixture Such an optimum or stoichiometric air fuel mixture is characterised by the excess air factor of Lambda 1 00 and it is imperative that the excess air factor is maintained precisely at this figure otherwise the catalytic converter cannot operate efficiently Even a deviation of only 1 has considerable adverse effects upon the after treatment But the best open loop control is incapable of holding the air fuel mixture within such close tolerances and the only solution is to apply an extremely accurate closed loop control featuring almost zero lag to the air fuel mixture management system The reason is that although an open loop mixture control calculates and meters the requ
43. n the same relationship in this case double the travel double the quantity then a constant drop in pressure must be guaranteed at the metering slits independent of the amount of fuel flowing through them The differential pressure valves maintain the drop in pressure at the metering slits constant independent of fuel through flow The difference in pressure is 0 1 bar this facilitates a high degree of control accuracy The differential pressure valves are of the flat seat type They are fitted in the fuel distributor and one such valve is allocated to each metering slit The upper and lower chambers of the valve are separated by a diaphragm The lower chambers of all the valves are connected with one another by a ring main and are subjected to the primary pressure delivery pressure from fuel supply pump The valve seat is located in the upper chamber Each upper chamber is connected to a metering slit and its corresponding fuel injection line The upper chambers are completely sealed off from each other The diaphragms are spring loaded and it is this helical spring that produces the pressure differential If more fuel flows into the upper chamber through the metering slit the diaphragm is bent downwards and enlarges the valve cross section at the outlet line leading to the injection valve until the differential pressure of 0 1 bar set by the spring again prevails If less fuel flows the diaphragm bends back towards its original position and decreases t
44. ncy or a rich mixture and increased power Lambda gt 1 This means air excess or lean mixture lower fuel consumption less power Lambda gt 1 3 This means that the mixture will no longer ignite the lean misfire limit LML has been exceeded Fuel management systems Fuel management systems whether of the carburettor or injection types have the task of preparing an optimum air fuel mixture Fuel management by means of manifold injection permits the optimum adaptation of the air fuel mixture to every operating phase of the engine It also ensures a lower level of pollutants in the exhaust gas In spark ignition systems fuel management is by means of either a carburettor or a fuel injection system Although up to now the carburettor has been the most commonly used method there has been a distinct trend in the last couple of years towards manifold fuel injection This trend came about due to the advantages offered by fuel injection as regards the demands for fuel economy high performance and last but not least a lower level of pollutants in the exhaust gas These advantages are based on the fact that manifold fuel injection permits extremely precise metering of the fuel depending upon the operating conditions of the engine and its load and taking environmental effects into account With manifold fuel injection the correct air fuel ratio is maintained so precisely that the pollutant level in the exhaust gas is considerably lower Since wi
45. nent mag net flux and the electro magnet flux resulting from the incoming ECU control signal are added whereas in the other two air gaps Figure 21 L4 La the fluxes are subtracted from each other This means that in each air gap the arma ture which moves the baffle plate is subjected to a force of attraction pro portional to the square of the magnetic flux Since the permanent magnet flux remains constant and is proportional to the control current from the ECU flowing in the electromagnet coil the resulting torque is proportional to this contra cur rent The basic moment of force applied to the armature has been selected so that when no current is applied from the ECU there results a basic differential pressure which corresponds preferably to A 1 This also means that in the case of control current failure limp home facilities are available without any further correction measures being necessary The jet of fuel which enters through the nozzle attempts to bend the baffle plate away against the prevailing mechanical and magnetic forces Taking a fuel throughfiow which is determined by a fixed restriction located in series with the pressure actuator the difference in pressure between the inlet and outlet is proportional to the control current applied from the ECU This means that the variable pressure drop at the nozzle is also proportional to the ECU control current and results in a variable lower chamber pressure
46. ng over rich when higher engine temperatures have been reached The warm up regulator control pressure regulator is the component which carries out this mixture control for the warm up period by changing the control pressure Warm up regulator The change of the control pressure is effected by the warm up regulator which is so fitted to the engine that it ultimately adopts the engine temperature In addition the warm up regulator is electrically heated which enables it to be precisely matched to the engine characteristic It comprises a spring controlled flat seat diaphragm type valve and an electrically heated bimetal spring In the cold state the bimetal spring exerts an opposing force to that of the valve spring and as a result reduces the effective pressure applied to the underside of the valve diaphragm This means that the valve outlet cross section is slightly increased at this point and more fuel is diverted out of the control pressure circuit in order to achieve a low control pressure As soon as the engine is cranked the bimetal spring is heated electrically and after starting it is also heated by the engine The spring bends and in doing so reduces the force opposing the valve spring which as a result pushes up the diaphragm of the flat seat valve The valve outlet cross section is reduced and the pressure in the control pressure circuit rises Warm up enrichment is completed when the bimetal spring has lifted fully from the valve spring
47. nt These er ustments include ME lever adjustment and lever rest ni rie pla position lve housing and t awitth adjustment Basic Lever Adjustment Remove the fuel distri rom the airflow housing Using a depth gauge measure wd m between the top af the housing and the roller on the levet The distance should be 0 74 to 0 75 in 19 1 mm If an adjustment needs to be made use a 3 mm Allen wrench to adjust the mixture screw a ae 7 piel eTa Remove the 6 enter af Ehe mirth Coat the holt with locking hd d n stall the halt finger tight Carefully center the by either ye balling it or using a 0 004 in gauge Tighten the 6 mm bolt If the cannot be centered it may be necessary to re the airflow assembly from the ear turn it upaide nal ras the lever on its fulcrum shaft When the is centered in order to verify that the ver do not hind try to lift the by pl a magnet on the center bolt 155 fuel ratio ustments P E Done TI ow Internet Z EI How to Tune and Modify Bosch Fuel Injection Google Book Search Microsoft Internet Explorer File Edit view Favorites Tools Help Back Ai dA search sjFavortes Media c3 Es amp If the magnet easily lifts the lever and without sticking or binding then the adjustm Sensor P fest Position The top side of the ea rest about 0 07 to 0 08 in aio m of the narrowest part of the venturi cune Although this sounds like a
48. of current to the differential pressure regulator won t make the car undriveable but there may be a little roughness because the mixture will be lean My VW Service Training contact warned me about a common cause of this electrical failure The 10 amp system fuse 1s auxiliary mounted on the outside of the fuse and relay panel he said People think it s a spare fuse and take it out to use it elsewhere I ve fixed cars that have been worked on for days simply by installing a fuse Won t hold Hot restarting trouble can usually be traced to a loss of residual pressure in the injector lines that promotes percolation you ll have to crank for quite a while to purge all those bubbles To check attach a pressure gauge to the fuel line that goes to the cold start valve run the engine shut it off and watch the needle If it doesn t hold at about 38 psi for at least 10 minutes the check valve in the pressure regulator is probably leaking The KE Jet control plunger inside the fuel distributor seats on an O ring so a small amount of clearance between the air sensor lever and the plunger engine off is required or residual pressure will be lost If you re used to other CIS s and you notice this clearance you may jump to the unfortunate conclusion that the sensor plate is out of adjustment and get yourself in trouble That little bit of free play 1s supposed to be there To see if it 15 make sure there s pressure in the system you can run the fu
49. olid particles entrained in it do not come into direct contact with the ceramic body In addition to the mechanical protection thus provided the changes in sensor temperature during transition from one operating mode to the other are effectively reduced The voltage output of the sensor and its internal resistance are dependent upon temperature Reliable functioning of the sensor is only possible with exhaust gas temperatures above 350 C unheated version and above 200 C heated version Heated Lambda oxygen sensor To a large extent the design principle of the heated Lambda sensor is identical to that of the unheated sensor The active sensor ceramic is heated internally by a ceramic heating element with the result that the temperature of the ceramic body always remains above the function limit of 250 C The heated sensor is equipped with a protective tube having a smaller opening Amongst other things this prevents the sensor ceramic from cooling down when the exhaust gas is cold Amongst the advantages of the heated Lambda sensor are the reliable and efficient control at low exhaust gas temperatures e g at idle the minimum effect of exhaust gas temperature variations the rapid coming into effect of the Lambda control following engine start short sensor reaction which avoids extreme deviations from the ideal exhaust gas composition versatility regarding installation because the sensor is now independent of heating from its surroundings
50. ot to make any sparks You should see a steady cone shaped spray pattern Disconnect the wires and no drops should appear at the valve tip for at least a minute If the powerplant tends to stall when cold because there s no fast idle examine the auxiliary air regulator With the coolant below 80 degrees F unplug the regulator s electrical connector start the engine and let it idle Pinch either hose that s routed to the regulator and idle speed should decrease slightly Let the engine reach normal operating temperature plug the connector back in and pinch again You should hear no change in rpm In cases where fast idle never kicks out see that current is reaching the heating element in the regulator that s what warms the bimetal and shuts off the flow of air by using a test light across the connector terminals with the key on No light means there s an open somewhere between the fuel pump relay and the plug
51. ow sensor is so designed that the sensor plate can swing back in the opposite direction past its zero position and thus open a relief cross section in the funnel A rubber buffer limits the swing back in the downward direction in the case of the updraft air flow sensor the swing back in the upwards direction is also limited by a rubber buffer A leaf spring ensures that the sensor plate assumes the correct zero position when the engine is stationary The sensor plate movements are transmitted to the control plunger in the fuel distributor by means of a lever system The weight of the sensor plate and the lever system are balanced by a counterweight Fuel distributor The fuel distributor meters allocates the correct amount of fuel to the individual cylinders in accordance with the position of the air flow sensor plate As already mentioned the position of the sensor plate is a measure of the amount of air drawn in by the engine The position of the plate is transmitted to the control plunger by a lever The control plunger controls the amount of fuel which is to be injected Depending upon its position in the barrel with metering slits the control plunger opens or closes the slits to a greater or lesser degree The fuel flows through the open section of these slits to the differential pressure valves and then to the fuel injection valves If sensor plate travel is only small then the control plunger is only lifted slightly and as a result only a
52. pick up the sample at the convenient tube you ll find in front of the manifold it has a blue rubber cap make sure the timinglis at 6 degrees BTDC and the idle speed is 900 rpm then look for 0 3 to 1 2 Altering the mixture requires drilling out a plug between the air sensor and the fuel distributor then inserting a long metric allen wrench but normally there ll be no reason to fool with this Garbage in If the computer isn t sending a proper signal to the differential pressure regulator check the inputs First the coolant temperature sensor which is of the NTC Negative Temperature Coefficient type that loses resistance as it gets hot At 32 degrees F there should be 6K ohms across its terminals at 68 degrees 2 5K ohms and at 176 degrees a mere 300 ohms Next measure oxygen sensor voltage which should range between about 1 10 and one volt A good straightforward test is to unplug the temperature sensor connector and bridge its leads with a jumper no resistance so the computer will think the engine s warmed up then separate the oxygen sensor lead from the green wire and observe the milli amp reading at the differential pressure regulator as before You should get 9 11 mA Now ground the green wire Within 20 seconds expect the meter to show 19 22 mA No Then check the wiring from the ECU to the oxygen sensor If that s okay the computer s probably bad which is an unusual but expensive occurrence A complete lack
53. r Fuel inlet primary pressure Fuel ta the injection valves Fuel retum to the pressure regulator Fixed restriction Upper chamber Lower chamber Diaphragm Q Pressure actuator i4 4 x5 DNE 12 13 14 pi Oo O L KS 9 ill L4 1 LILI LILI T Wu Dane ill inknawn Zone A 3 http rb k bosch de resources literatur leseproben uz13e pdf Microsoft Internet Explorer File Edit iaa To Favorites Help da Back p fx fat Gh Search GJ Favorites i Media ga Eh E Attachments Comment 5 D ia Qe e OA Section through the electro hydraulic pressure actuator 1 Fue inlet primary pressure 2 Nozzle 3 Bafle plate 4 Fue outlet 3 Magnetic pole 6 Electromagnet cod T Penmanent magnet flux 8 Permanent magnet turriesd through BO degrees from the focal plane iLi to La air gaps Function The magnetic flux of a permanent mag net broken lines in Figure 21 and that of an electromagnet unbroken lines are superimposed upon each other in the magnetic poles and their air gaps The permanent magnet is actually turned through 90 degrees referred to the focal plane The paths taken by the magnetic fiuxes through the two pairs of poles are symmetical and of equal length and fiow from the poles across the air gaps to the armature and then through the armature In the two diagonal y opposed air gaps Figure 21 L L3 the perma
54. rectly around the electric motor There is no danger of explosion however because there is never an ignitable mixture in the pump housing The pump delivers more fuel than the maximum requirement of the engine so that the pressure in the fuel system can be maintained under all operating conditions During starting the pump runs as long as the ignition key is operated The pump continues to run when the engine has started A safety circuit is incorporated to stop the pump running and fuel being delivered if the ignition is switched on but the engine has stopped turning for instance in the case of an accident Fuel accumulator The fuel accumulator maintains the pressure in the fuel system for a certain time after the engine has been switched off When the engine is running it serves to deaden the noise of the electric fuel pump After the engine has been switched off the fuel accumulator maintains the pressure in the fuel system in order to facilitate re starting particularly when the engine is hot The design of the accumulator housing is such that it deadens the noise from the fuel pump when the engine is running The interior of the fuel accumulator is divided into two chambers by means of a diaphragm One chamber serves as the accumulator volume for the fuel the other chamber contains a spring During operation the accumulator chamber is filled with fuel This causes the diaphragm to bend back against the force of the spring until it is halted by
55. regulator balance each other out If for instance the fuel pump delivers slightly less fuel the plunger is shifted by the spring into the corresponding new position and in doing so reduces the open section of the port through which excess fuel flows back to the tank This means that less fuel leaves the system at this point and as a result the primary pressure in the system increases to the specified value When the engine is switched off the fuel pump also stops running The primary pressure drops to below the injection valve opening pressure The pressure regulator closes the return flow port and prevents further pressure reduction in the fuel system Fuel injection valve The fuel injection valves open at a certain pressure and inject fuel into the intake tubes The fuel is atomised by the oscillation of the valve needle The injection valves inject the fuel allocated by the fuel distributor into the intake ports directly in front of the intake valves of the cylinders The injection valves are secured in a special holder in order to insulate them from engine heat The insulation prevents vapour bubbles forming in the fuel injection lines which would lead to poor starting behaviour when the engine is hot The injection valves have no metering function They open of their own accord when the opening pressure of 3 3 bar is exceeded They are fitted with a valve needle which vibrates chatters audibly at high frequency when fuel is injected This mean
56. rflae Sensor Plate If the airflow sensor plate binds on the way up fuel flow will be limited and the engine will sag or stumble Sticking or Binding Control Plunger If the control plunger binds on the way up fuel flow will be limited and the engine will stumble or sag Incorrect System or Warm Controd Pressure If the system pressure is too high or if the control pressure js too high high system pressure will usually cause high control pressure the movement Of the control plunger will be limited and the engine will begin to run lean as the airflow increases A lean running engine will sag or stumble on acceleration LUnegqual Injector Plow Restricted injectors can limit the amount of fuel that can pass through them thereby limiting power Engine Diesels Binding or Sticking Airflow Sensor In order for the engine to diesel or run on after the engine is shut aff there must be fuel entering the engine One aree of this fuel is an airflow sensor that is nat dropping to the closed position as the engine is ahut otf Binding or Sticking Control Plunger Inspect the control plunger for smooth movernent without binding or sticking Lenking Injectors Perform an injector flow test and inspect the injectors f r proper seating when the airflow sensor drops to the rest position Leaking Cobld Shart fection Remove injector pres surize the system and inspect for leaks Excessive Fuel Consumption Impropert Adjusted Air Fuel Ratio Check
57. rmo time switch Sticking Control Plunger A sticking control plunger normally indicates a damaged control plunger Simply dropping the plunger when servicing the fuel distributor might be enough to damage it Inapect the plunger for evidence of varnishing If the plunger continues to stick or bind replace the fuel distributor Care during installation will prevent damage to the new plunger Note Control plungers are machined for a pre cise match to a given fuel distributer Trying to wee a control plunger from another fuel distributor can result in even more severe binding or leaking Restricted Injectors Restricted injectors can best be diagnosed by performing the injector fow equality test Cleaning 4 restricted injector s can be done with an injector cleaning system These cleaning systems range in price from about 100 to more than 1 000 Unless you are a business specializing in friet Injection or tune up service purchasing a cleaning system such as this is probably not the best uae of your money As an alternative remove the injectors fram the intake system and leave them attached to their fuel supply lines Place them in a safe container then activate the fuel pump as described in the section on measuring pressures Once the fuel pump is running lift the airflow sensor plate all the wav and allow fuel to flow through the injectors at full force Lower the airflow sensor plate to its rest position wait a few seconda then
58. s that excellent fuel atomisation is achieved even with the smallest of injected quantities When the engine is switched off the injection valve closes tightly and forms a seal when the fuel system pressure has dropped below the injection valve opening pressure As a result no more fuel can drip into the intake ports after the engine has been switched off Bosch K Jetronic Fuel Injection Part 2 Fuel Management Mixture control unit The task of fuel management is to meter or allocate the correct quantity of fuel which corresponds to the amount of air drawn in by the engine Fuel management carried out by the mixture control unit This comprises the air flow sensor and the fuel distributor Air flow sensor The air flow sensor operates according to the suspended body principle and measures the amount of air drawn in by the engine All the air drawn in by the engine flows through an air flow sensor which is connected upstream of the throttle plate The air flow sensor is fitted with an air funnel in which is located a movable sensor plate the suspended body The air drawn in through the air funnel shifts the sensor plate by a certain amount out of its zero position The movement of the sensor plate is transmitted to a control plunger by a lever system This plunger determines the quantity of fuel required Considerable pressure shocks can occur in the intake system if backfiring takes place in the intake manifold For this reason the airfl
59. s to run rich the Lambda voltage increases The system computer edu the current through the electro hydraulic actuator and injection amp ystem leans into the engine The airflow li put which in turn lifts the control plunge pore distributer When the plunger is lifted fuel flaws from the lower chambers of the distributor through the metering slits inte the upper chambers and off to the injectors As the airflow changes the position of the plunger changes thereby altering the amount of fuel entering the engine When the engine is started the cold start valve will spray for about five to ten seconds If the temperature of the engine is greater than 85 deg F the cold start injector will not operate During engine warm up the coolant input to the system computer causes the BE to increase the ipud Maris the electro hydraulic actuator en the mixture As the engine warms up the current dropa leaning out the mixture When the engine reaches operating temperature the coolant m wav to the Lambda During warm operation the airflow lifts the fuel distributor control plunger iall to the volume of entering the engine As the plunger is lifted f ows through the metering alits from the lower to the upper chambers of the fuel distributor If the pressures in the lower chamber are equal to or lower than the How CIS E Works When the engine 15 cranked Ec to 21i x Ai Fage 155 a gt Exit full screen
60. small section of the slot is opened for the passage of fuel With larger plunger travel the plunger opens a larger section of the slits and more fuel can flow There is therefore a linear relationship between sensor plate travel and the slit section in the barrel which is opened for fuel flow The force applied to the control plunger by the sensor plate travel is opposed by another force which comes from the so called control pressure One of the functions of this control pressure is to ensure that the control plunger follows the movements of the sensor plate immediately and does not for instance stay in the upper end position when the sensor plate moves back down again Further important functions of the control pressure are discussed in the chapters dealing with warm up and full load enrichment Control pressure The control pressure is tapped off from the primary pressure through a restriction bore which serves to decouple the control pressure circuit and the primary pressure circuit from one another A connection line joins the fuel distributor and the warm up regulator control pressure regulator When starting the cold engine the control pressure is about 0 5 bar As the engine warms up the warm up regulator increases the control pressure to about 3 7 bar The control pressure acts through a damping restriction on the control plunger and thereby develops the force which opposes the force of the air in the air flow sensor In doing so the r
61. ssure the fuel mixture can be enriched or enleaned in response to temperature and oxygen sensor signals Typical control counter pressures are 4 to 7 psi less than system pressure on a fully warmed engine and 17 to 20 psi less than system pressure on a cold engine typical system pressures are 5 0 to 5 5 bar or 75 to 85 psi The signal to the differential pressure regulator from the computer is measured in milliamps of current To test this signal a DVOM must be placed in series with the differential pressure regulator Typical current values are 80 milliamps cold engine 15k ohm resistor in place of coolant temp sensor to simulate a cold engine condition 120 milliamps during cranking this is a crank enrich function to aid starting and 8 to 12 milliamps warm idle Note always check service manual for values These values correspond to the fuel pressures listed In other words at 80 milliamps current you should show 17 to 20 psi less than system pressure Rest pressure is the fuel pressure maintained in the system by the fuel accumulator after engine shutdown The fuel accumulator is a large spring loaded diaphragm that maintains a pressure of about 1 5 to 2 0 bar for 30 minutes or more after engine shutdown This rest pressure provides for fast restart and prevents fuel percolation or boiling vapor lock Always check the service manual for the car line you are working on for proper rest pressures and times Typical symptoms caused by accumul
62. start valve In doing so the warming up of the switch due both to the engine heat and to the surrounding temperature as well as its in built electrical heating filament are the determining factors The in built heating facility is necessary in order to limit the maximum start valve injection period The mixture would otherwise become too rich and the engine would not start due to flooding During cold start the injection period depends mainly upon the electrical heating facility Switch off at 20 C after approx 8 seconds On the other hand when the engine is already warmed up the heat from the engine has heated the thermo time switch to such a degree that it remains permanently open As a result an engine which is already at operating temperature is not provided with extra fuel for starting Warm up Warm up enrichment is controlled by the warm up regulator When the engine is cold the warm up regulator reduces the control pressure to a degree dependent upon engine temperature and thus causes the metering slits to open further At the beginning of the warm up period which directly follows the cold start some of the injected fuel still condenses on the cylinder walls and in the intake ports This can cause combustion miss to occur For this reason the air fuel mixture must be enriched during the warm up phase Lambda lt 1 0 This enrichment must be continuously reduced along with the rise in engine temperature in order to prevent the mixture bei
63. tage sheuld increase amp bout 7 0 volis If the increase in voltage is not smooth replace the potentiometer If the voltage apecifications sre incorrect Jansen the mounting screws and adjust Throttle Valor Housing The minimum throttle adjustment ie done with a thin piece of paper Loren the throttle 8m rew and place the paper between he p er and the throttle Adjust the screw unt Mae i pinches the paper Then remove the paper and tighten the screw an additional half turn Throttle Suvich Connect an ahmmeter across the terminals af the closed throttle switch Continuity should be gained just before the throttle is closed Next connect an ohrmireter across the terminals of Lhe wide open throttle switch Continuity should he gained just before the throttle is wide open Mercedes Benz Two adjustments need to be made on Mercedes Benz applications aurflow mm adjust ment and air low ERN adj urat ment Arfi pee EET Adjustment Pregaurize the fuel syst ig can be done by removing the fuel pump relay and placing a jumper wire with n 16 amp fuse between terminals 7 and 8 The sirfaw n ahould he centered in the narrant D venturi This uaually means a gap all the way around the airflow of abet 0 002 in If the aM nit cece loosen the center belt ice he ns should not bind when pressed down iind The rest position of the should place the top of the sensor pit 0 00 n belom the top edge of the AA of the venturi The distance between
64. th this system the carburettor is no longer required the intake paths can be optimally designed and laid out This results in better cylinder charge which in turn leads to a more favourable torque characteristic What types of mixture formation are available using fuel injection There are both mechanically and electronically controlled systems available The K Jetronic is a mechanical fuel injection system which injects continuously and which needs no form of drive whatsoever Electronically controlled systems The fuel is supplied by an electrically driven fuel pump which develops the pressure necessary for injection The fuel is injected by solenoid operated fuel injection valves into the cylinder intake ports The injection valves are controlled by an electronic control unit ECU and the amount of fuel injected depends upon the length of time that they stay open By means of sensors the ECU is provided with information about the operating conditions of the engine and about the ambient conditions around the vehicle The basis for assessing the amount of fuel to be injected is the amount of air drawn in by the engine The L Jetronic is an electronically controlled fuel injection system In the case of the L Jetronic the amount of air drawn in by the engine is directly measured by an air flow sensor Electronically controlled fuel injection systems are dealt with in detail in the Publication Electronically Controlled Fuel Injection in the Bosch
65. the airflow lever and the bottom of the control plunge play Ves unen Andi ener piste free plav O x Ai Fage 155 yr CI Exit full screen e Done imi m m Internet Z E How to Tune and Modify Bosch Fuel Injection Google Book Search Microsoft Internet Explorer Edit view File Favorites Tools Help Back fx EA Search j Favorites ir Media A E E Address amp http books google com baoks id uuT AwfFCOYO EC amp pg PA1568Ipg PA1568 amp dq aird Flow4 Qa should be 0 040 to 0 080 in If gently lifting the AM not reveal this tolerance then prn play by driving the guide pin up or down as required Airflow Potentiometer Adjustment There should n 3 200 and 4 500 ohms of resist ance between terminals 14 and 18 of the airflow potentiometer when the airflow is mL rest There should be between 560 and 1 060 ohms from terminal 14 to terminal 17 The reading should increase to between 3 760 and 5 640 when the pow poe ia lifted to ita highest point Adjust if Troubleshooting the KE Jetronic System Of all the Bosch systems the KE system may be the most confusing to troubleshoot The system combines electronics with mechanical fuel control An analysis of driveability symptoms point to either a mechanical or electronic problem or noi distinguish between the two What follows is a logical sequence for analyzing any driveability problem Verifv Engine Condition Run a compression test and or cyl
66. the upper stops and is pressed against the lower stops The inner spring is relieved of tension and the control pressure reduced by the specified amount as a result In this manner mixture enrichment is achieved Controlling the air fuel mixture In order to adapt the injected fuel quantity to the ideal air fuel ratio of Lambda 1 the pressure in the lower chambers of the fuel distributor is varied If for instance the pressure is reduced the differential pressure at the metering slots climbs accordingly with the result that the injected fuel quantity is also increased In order to be able to vary the pressure in the lower chambers these are decoupled in contrast to the conventional K Jetronic fuel distributor from the primary pressure Decoupling is by means of a fixed throttle A further throttle connects the lower chambers with the fuel return This throttle is variable If it is open the pressure in the lower chambers can reduce If it is closed the primary pressure is present in the lower chambers If this throttle is opened and closed rapidly it is possible to vary the pressure in the lower chambers to correspond to the ratio between open time and close time An electromagnetic valve the timing valve is used as the variable throttle It is controlled by electrical pulses from the Lambda control unit Bosch K Jetronic Fuel Injection Part 3 Electrical Circuitry If the engine stops but the ignition remains switched on the electric f
67. through a frequency valve By modifying lower chamber pressure a change in volume of injected fuel is made enriching or enleaning the mixture The frequency valve is nothing more than an electrically duty cycled fuel pressure regulator controlled by an on board computer in response to an oxygen sensor signal This system provides a more precise and rapid control of fuel mixture Typical duty cycle on a properly running engine is 45 percent to 55 percent duty and fluctuating A quick test of this system is to start the engine and test the frequency valve for vibration or noise it should vibrate Also unplugging the oxygen sensor will put the system in open loop and fix the frequency valve at a 50 percent duty cycle The KE Jet system provides quicker response and more precise control of fuel mixture than the K Jet Lambda system and is the current K Jet system in use This system uses a device called a differential pressure regulator to control fuel mixture in response to both engine temperature and oxygen sensor signals In the KE Jet system counter pressure is broken down into primary counter pressure and control counter pressure Primary counter pressure is the pressure applied to the top of the fuel plunger This pressure stays constant and is the same as system pressure Control counter pressure is modified by the differential pressure regulator and is actually the lower chamber pressure in the fuel distributor By modifying lower chamber pre
68. ty of hydrocarbons are present in the exhaust gas from IC engines In the presence of oxides of nitrogen and sunshine they produce products of oxidisation A number of hydrocarbons are detrimental to health Catalytic after treatment The toxic emissions of the spark ignition engine can be considerably reduced by the use of catalytic after treatment The exhaust gas emission level of an engine can be influenced at three different points The first possibility of influencing the emissions is during the mixture formation stage before the engine The second possibility is the use of special design measures on the engine itself for instance optimised combustion chamber shape The third possibility is after treatment of the exhaust gases on the exhaust side of the engine whereby the task is to complete the combustion of the fuel This is carried out by means of a catalytic converter which has two notable characteristics e The catalytic converter promotes the after burning of CO and HC to harmless carbon dioxide CO2 and water HO e Atthe same time the catalytic converter reduces the nitrogen of oxide present in the exhaust gas to neutral nitrogen N It is therefore perfectly clear that the catalytic after treatment of the exhaust gas is considerably more effective than for instance the purely thermal after burning of the exhaust gases in a thermal reactor Using a catalytic converter more than 90 of the toxic substances can be converted to harm
69. uel pump is switched off The K Jetronic system is equipped with a number of electrical components such as electric fuel pump warm up regulator auxiliary air device start valve and thermo time switch The electrical supply to all of these components is controlled by the control relay which itself is switched by the ignition start switch Apart from its switching functions the control relay also has a safety function A commonly used circuit is described in the following Function When cold starting the engine voltage is applied to the start valve and the thermo time switch through terminal 50 of the ignition start switch If the cranking process takes longer than between 8 and 15 seconds the thermo time switch switches off the start valve in order that the engine does not flood In this case the thermo time switch performs a time switch function If the temperature of the engine is above about 35 C when the starting process is commenced the thermo time switch will have already open circuited the connection to the start valve which as a result does not inject extra fuel In this case the thermo time switch performs as a temperature switch Voltage from the start ignition switch is still present at the control relay which switches on as soon as the engine runs The rotational speed reached when the starting motor cranks the engine is high enough to generate the engine running signal which is taken from the ignition pulses coming from
70. ure and power reasons to operate the engine with an air fuel ratio which deviates from the Lambda 1 figure Similar to the acceleration range a sensor signals the full load operating mode to the closed loop control unit which then switches the fuel injection to the open loop mode and injects the corresponding amount of fuel Deviations in air fuel mixture The Lambda closed loop control operates in a range between Lambda 0 8 1 2 in which normal disturbances such as the effects of altitude are compensated for by controlling 1 to 1 00 with an accuracy of 1 The control unit incorporates a circuit which monitors the Lambda sensor and prevents prolonged marginal operation of the closed loop control In such cases open loop control is selected and the engine is operated at a mean Lambda value E How to Tune and Modify Bosch Fuel Injection Google Book Search Microsoft Internet Explor m x File Edit View Favorites Tools Help Back gt fx Pi E Search amp jFavorites Media ga ET E Address amp http Jbaaks gaeagle cam books id uuT AwFOvYOEC amp pg PA1458lpg PA145 amp dq basch4 CQ GL Engine Backfires in Intake Check for Proper CO Adjustment A lean mixture adjustment can result in a backfire under load or when starting Check Engine Air Tubing between Airflow Sensor and Throttle Holes or other leaks in the tubing that rire from the airflow sensor to the throttle assembly ean result in a lean
71. ure in the lower chambers with no correction Mercedes Benz men per adjustments based on engine temperature and exhaust oxygen Disconnect the electrical connector on the differ ential pressure regulator and close the valve on the pressure gauge Activate the fuel pump the differ ential pressure should be between 2 9 and 7 0 psi If the pressure does not meet these specifications disconnect the return line from the lower cham bers of the fuel distributor A volume of approx imately five ounces per minute should through the return line If the pressure 15 w but the i correct replace the differential pressure lator If the zi is incorrect replace the fuel distributor lf the first part of the test yields the correct pressure then reconnect the differential pressure regulator with an ammeter in series and proceed with the second part of the test The second step is to simulate the differential pressure of a cold engine Disconnect the coolant temperature and place a 15 000 ohm resistor across the nals Activate the fuel pump Differential pressure should be between 10 0 and 17 5 pei The ammeter should read between 50 and 80 milliamps If the pressure is wrong but the current is cor rect replace the differential pressure regulator If both the ammeter and pressure readings are incorrect check the resistance through the differ ential pressure regulator If the resistance is greater than 21 5 ohms or less than 17 5 ohms repla

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