Multi-Port Injection (MPI) - Справочник Honda Civic EJ9
Contents
1. Scan Tool e Inputs Outputs Part 2 e Scan Tool Advanced e Engine Control Module e Monitor Tests Overview e Air Flow MAP Sensor Base Inj Pulse Width e Comprehensive Component Monitor e Fuel Delivery System e Catalyst Monitor e Closed Loop Strategies Theory e EGR Monitor e Closed Loop Strategies Case Studies e Evaporative Monitor e Thermistor Inputs e Fuel System Monitor e Throttle Position Sensor e Misfire Monitor e EGR Valve Lift Sensor e Oxygen Sensor Monitor e MAP BARO Sensor e Oxygen Sensor Heater Monitor e Ignition Inputs e P Codes e Vehicle Speed Sensor e Oxygen Sensor e Lean Air Fuel Sensor e Miscellaneous Input Signals e Fuel Injectors Miulti Port Injection e Fuel Injectors Dual Point Injection e Ignition System Outputs e Idle Air Control Valve 2000 All Rights Reserved Sure Seal Products Inc Greensboro NC Miscellaneous Training Material e Glossary of Terms Visit Our Website www tech2tech net Page 20 1 20 Fuel Injectors Multi Port Injection 20 1 General Overview The fuel injector is a solenoid style output device that directly controls fuel deliv ery into the intake manifold The injectors are operated by a duty cycle type signal from the engine control module ECM The amount of fuel delivered is directly Image 20 1 proportionate to how long the ECM keeps the injector open The PGMFI system can be a multi port injection MPI system or a dual point inje2. is turned on when the ECM provides a ground Actually if any part of the wire from the injector to the ECM comes in contact with a ground the injector will be turned on I got involved in diagnosing a car where some stereo equipment was installed and a mounting screw was screwed into the PGMFI harness and shorted one injector 4 ground wire This meant that every time the car was started that one injector was turned on all the time All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_ 002 Visit Our Website www tech2tech net Page 20 9 This car was a little tough to diagnose let s look at some of the reasons No DTC Prior to OBD II the outputs were not monitored for functionality and this problem would not set a DTC Every time the ECM wanted the injector to turn on it gave the circuit a ground If the circuit already had a ground no big deal Normal to Lean Pulse Width Since the 4 injector that was permanently grounded you would not see a problem with the PW waveform unless you happened to hook a DSO to the 4 injector I typically check one injector 1 and was missing the problem injector The PW on any of the other injectors would be normal or possibly even lean The remaining injectors could be lean since the rich input from the O2 sensor would be driving the computer to lean out the mixture Normal PW Parameter from Scan Tool The PW indicated by a scan tool would show n
3. Module 20 Fuel Injectors Multi Port Injection MPI Author E mail URL Grant Swaim sureseal nr infi net www tech2tech net IMPORTANT READ Do not read or study this information unless you agree to the following conditions The information in this training module is the intellectual property of N Grant Swaim and is copyrighted by Sure Seal Phone 336 632 9882 Products Inc Fax 336 632 9688 Subscribers to the Tech 2 Tech website and persons partici i pating in Tech 2 Tech s on line training program are entitled to read this material on line Postal Address Tech 2 Tech Website PO Box 18443 You may also click on the save icon on the Acrobat viewer Greensboro NC 27419 and save a copy to your local computer You may save a copy of this file on one computer and it must be viewed from 2 that ter Physical Address 220 4 Swing Rd BT ee Cape Greensboro NC 27409 You may also print one copy of this file for your viewing If the printed copy becomes illegible or lost an additional copy may be printed Last Update April 2000 Tech 2 Tech offers the following training modules in printed manual CD ROM and on line formats PGMFI Training Modules OBD II Training Modules e The PGMFI System Overview Part 1 e On Board Diagnostics General Overview e The PGMFI System Overview Part 2 e Diagnostic Trouble Codes e PGMFI Flash Type DTCs e MIL Freeze Frame e Inputs Outputs Part 1 e
4. The injectors are made in two parts plastic and steel and they will sometimes develop a leak where the two parts are crimped together If the injector is leaking at the crimp replace it If the injector is getting wet with fuel on the top half it could be coming from a leaking injector o ring To determine if it is leaking at the top injector o ring or the injector crimp you will have to dry everything off and watch for the source of the fuel Many times a tech will replace the top injector o rings when it is a leak ing injector This just creates a customer comeback and additional work It is my experience that the upper injector o rings do not normally start leaking from age They usually leak whenever the fuel injector was pulled and replaced and new o rings were not used If you are getting a fuel leak in the injector area and the injectors have never been pulled suspect a leaking injector body All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_ 002 Page 20 8 Visit Our Website www tech2tech net 20 6 3 Wrong Injectors Unfortunately virtually all the Honda MPI injectors have the same external di mensions It is not uncommon to find a wrong set of injectors in a Honda Once you have seen this a few times it is fairly easy to diagnose Let s take a look at the two scenarios Injectors Are Too Small If the injectors in an engine were designed for a smaller displacement en gine
5. bodies These two issues are covered in detail in the Service Tips sec tion at the end of this module As far as testing the injectors on the car you have three choices checking the injector s PW the injector s winding resistance and monitoring the injector s current 20 5 1 Injector Pulse Screen Capture 20 1 Width You can actually meas UTIL Cont Grat Print Injector On Comm _ Injector Off Main Menu 6 0u Ims ure voltage at the ground side of the injec tor and determine the injector s PW While this is a very useful test for diagnosing fuel de livery problems it is not real effective in finding injectors with stuck pintles The best way to confirm an injector s pintle is opening and All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_002 Page 20 4 Visit Our Website www tech2tech net closing is to monitor the injector s current with a DSO The PW can be measured with a digital storage oscilloscope DSO as shown on Screen Capture 20 1 on the left Battery voltage is present on the ground side of the injector when it is turned off since there is no ground and subsequently no current is flowing in the injector cir cuit When the injector is turned on the voltage is pulled close to 0 volts as the driver transistor provides a ground The length of time the pintle is held open by the continued current in the injector winding can be measure
6. ction DPI system The MPI system is by far the more popular of the two systems This module covers the MPI system only Chapter 21 Injectors Dual Point Injection covers the DPI system The bottom fuel injector in Image 20 1 is a MPI injector The top two injectors are DPI injectors Virtually all MPI in jectors look identical and have the same external dimensions The o ring on the inlet of the injector should be replaced anytime the injector is removed and reinstalled 20 2 How Do They Work Illustration 20 1 Typical Fuel Injection Schematics As can be seen in Illus Injector Resistors Data Stream Engine Control Module tration 20 1 the injector circuit is supplied bat tery voltage from the main relay The main relay will supply power to the circuit for 2 sec onds after the key is first turned on then only if the engine is running Processor Most of the MPI sys tems used an external resistor pack as shown in the drawing The newer model Hondas have dropped the exter nal resistor packs and All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_002 Page 20 2 Visit Our Website www tech2tech net have added the resistance to the injector itself All external resistance packs added 5 7 ohms to each of the injector circuits The injector windings are the next item in the injector circuit The injector windings will either be 1 2 2 5 ohms with exte
7. d by looking at the bottom time line The time between the injector on time and the injector off time is the PW The injector off time is indicated by the voltage returning to battery voltage When the ground is released there is an inductive spike produced by the collapsing electromagnetic field this is normal The PW of the screen capture in Figure 4 is 2 75ms You can see that the time division is set up for Ims per division The injector is grounded for 2 75 divisions 20 5 2 Injector Resistance The only injector test that is covered in Injector Resistance Values y ne the Honda service manual is an injector in Ohms f i resistance test The resistance informa Model Injector Resistor tion was also dropped from the later Year Ohms Ohms model manuals Based on field observa Accord tions I was able to complete this infor mation up thru 1998 85 97 1 5 2 5 5 7 All MPI injectors with an external resis 2 nase bolas tance pack will measure 1 5 2 5 ohms Civic MPI across its winding There should be no 85 91 115 25 15 7 continuity from the winding to the in jector body 92 98 10 13 N A All external injector resistor packs are Odyssey 5 7 ohms 95 97 1 5 2 5 5 7 All MPI injectors with an internal resis 98 10 13 N A tor measure 10 13 ohms across its winding There should be no continuity Prelude from the winding to the injector body 85 96 1 5 2 5 5 7 97 98 10 13 N A All Rights Rese
8. e 20 7 20 6 Service Issues Honda fuel injectors are reasonably durable Many Hondas go a lifetime on the original set There are a few service related situations related to fuel injectors and I have included some of them here Some are somewhat common and some are rare but you need to know about them 20 6 1 Poor Spray Pattern From time to time you may experience a Honda that has a driveability problem runs poorly when cold or is failing an emissions test This could be caused by an injector that has a poor spray pattern Fuel that is not atomized correctly by the injector is hard to ignite and will not burn completely A poor spray pattern could be cause by partially clogged or dirty injectors Poor injector spray patterns typi cally tend to cause more driveability problems on cold starts If you suspect a problem with a fuel injector there is no real easy way to test one other than to replace it with a known good injector Fortunately changing injec tors on a Honda is very easy 15 20 minutes If you do not have a spare test injector you can try swapping an injector on a cylinder with a miss to one that does not miss If the miss moves with the injector the injector is bad The only effective way to repair this problem is to replace the injectors preferably as a Set 20 6 2 Leaking Injectors The biggest problem with Honda injectors is not usually any performance related issue It is simply a fuel leak in the injector body
9. for a given pulse width the car will be running lean This is more no ticeable in open loop OL since the oxygen O2 sensor feedback cannot help richen the mixture The typical scenario is the O2 sensor will fix on lean low volts since the small injector cannot deliver adequate fuel This will eventually set a diagnostic trouble code DTC 1 When you check a car with a DTC 1 first check to see if the O2 sensor is fixed at a high or low voltage If the injectors are too small it will be fixed on a low voltage When you check the injector s PW you will probably find it from normal to wide The ECM is trying to drive the fuel system richer but within the window of authority of the O2 sensor When you see O2 fixed on lean and the PW normal to rich the fuel deliv ery system is not supplying enough fuel to satisfy the O2 sensor There are many things that can cause this problem and injectors that are too small are one of them Injectors Are Too Big This is the same scenario as before but in reverse The car will come in with a DTC 1 and the O2 sensor is fixed on a high voltage rich signal Again the PW will be normal to narrow For more information on diagnosing cars with the wrong size injectors see the case studies at the end of Chapter 10 Closed Loop Case Studies 20 6 4 Shorted Injector Ground Wire This might be a long shot but it has happened I helped diagnose the car As you can see from Illustration 20 1 the injector
10. n milli seconds ms The unit of measure for injector operation should always be time not a duty cycle or dwell unit When injector operation is measured as a duty cycle the value be comes RPM dependant The injector s PW will vary depending on many inputs The ECM turns the injec tor on the correct amount of time to deliver the optimum amount of fuel for the given conditions In addition to delivering the correct amounts of fuel there are two occasions when the injectors are turned off totally This happens at a pre programmed high rpm and during deceleration periods The typical PW of a MPI system at idle with no load is 1 75 2 75ms All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_ 002 Visit Our Website www tech2tech net Page 20 3 20 4 Component Loca tion Image 20 2 The PGMFI MPI System Multi Port System The MPI system was by far the most popular sys tem used The MPI has an injector for each cyl inder The injectors can be eas ily seen from the top shown at arrow in Im age 20 2 MFI systems have been used on 85 98 Accords 95 98 Odysseys 85 98 Civics 85 98 Preludes 20 5 How Do You Test Them Just like most other Honda fuel infection components the fuel injectors are fairly fool proof An electrical failure is very uncommon The two more common prob lems that you might experience with a Honda are poor spray patterns and leaking injector
11. n the base pulse width that is established by internal tables These injectors will typically have your O2 sensor pegged at 9 and eventually will set a DTC 1 If the car is for off road use this is not a real problem If the car is used for every day driving it may be difficult to pass emissions tests and not damage the cata lytic converter from the excessive fuel being delivered by the incorrect injectors All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_ 002
12. nductive reactance is no longer affecting the current and the current is being controlled by the resistance of the circuit The characteristics of this current ramp are directly controlled by the characteris tics of the coil in the circuit The slope change of slope and other characteristics of the ramp can give an indication of the condition of the coil in the circuit In general when a coil has shorted windings the ramp will climb much faster and take on a bowed out appearance This would be an indication of a failing injec tor Point B Since the ramp is controlled by the characteristics of the coil in the circuit some thing must have changed to the characteristics of the coil at point B The change was that the pintle moved When the metal pintle moves inside the injectors wind ing it changes the inductive reactance of the injector s winding This subtle change in the injector s inductive reactance causes this change in the current ramp and is often called a pintle bump hump All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_ 002 Page 20 6 Visit Our Website www tech2tech net So by checking the injector s current we can actually tell if and when the pintle opened You can quickly compare the current on all injectors and confirm that they are all opening at approximately the same point on the current ramp Point C At point C the current has reached the saturation poin
13. ormal to lean When you are reading data stream off the ECM you are seeing what the ECM proc essor commanded the injectors to do not what they did While not all scan tools are capable of retrieving the PW parameter from a Honda a Mas tertech with Honda software will We finally caught this car after checking the PW on all the injectors with a DSO The moral of this story is if a Honda comes in rich and the first injector you check looks OK check the rest of them It only takes a few more minutes but it can save you some time if you discover that an injector is staying on due to a grounded injector wire 20 6 5 Don t Trust Data Stream If you have a scan tool that is capable of reading PW on a Honda it is handy to use but beware that in some cases you might still need to check PW at the injec tor with a DSO As shown in Illustration 20 1 the information that is read from a scan tool comes straight off the processor of the ECM The PW parameter indicated on a scan tool is the amount of time the processor commanded the injector to stay on The trig ger signal is sent to a transistor driver mounted on the inside edge of the ECM box Just because the ECM commanded an injector to turn on for 3ms does not necessarily mean that it did Many situations including a defective driver transis tor or an open or grounded injector wire will cause the actual injector PW to differ from the commanded amount All Rights Reserved 2000 Sure Seal P
14. rnal resistor pack or 10 13 ohms with internal resistor It is not common for an injector winding to fail or short The added resistance in the injector circuits is for current control Full battery voltage is applied across the injector initially to get the pintle to open quickly Af ter the current starts to flow the added resistance in the circuit will drop the cur rent back to a lower level Once the pintle is open it does not require much current to keep the pintle open The injector windings are grounded by driver transistors in the ECM When the processor of the ECM commands the injector on a signal is sent to the injector driver and the transistor grounds the injector until the processor stops command ing the injector on Since the ECM is controlling the ground if the wire from the injector to the ECM were to become grounded the ECM would not be harmed 20 3 Fuel Delivery Strategies The fuel injector is the output device that is responsible for directly controlling fuel delivery The fuel pump and regulator supply the inlet of the injector with a constant regulated supply of fuel The fuel is even adjusted for changes in the manifold pressure so that the pressure differential between the fuel supply and the intake manifold is always constant The amount of fuel injected is directly proportional to the amount of time the fuel injector is turned on The injector on time is typically referred to as pulse width PW and is measured i
15. roducts Inc This manual printed 4 9 00 from the file pgmfiobd_ 002 Page 20 10 Visit Our Website www tech2tech net If you suspect the PW information being retrieved by a scan tool you will need to check the PW of every injector with a DSO 20 6 6 Hot Rods Removing the Rev Limiter Among the hot rod crowd many swap chips to remove the RPM limiter First of all this alone is not a simple task The aftermarket chip companies have to unsol der your factory chip and solder in a socket for their chip But assuming that you wanted to do this to your ECM and trust the engineering department of an inde pendent chip manufacturer over the engineering department of Honda consider this issue The RPM that Honda has chosen to limit a given engine is used in the sizing of the injector When the engine reaches the RPM limit the injector PW is close to saturation about 80 duty cycle The injector is spraying virtually constantly By removing the RPM limit and running the engine even higher the injectors may not be capable of injecting enough fuel The car will lean out due to the physical limitations of the injectors Some sources sell racing injectors which have larger pintles They are probably stock injectors meant to be installed in a larger displacement Honda engine The only problem with installing larger injectors to fix the top end lean problem is that they will run too rich at idle The ECM cannot command the injectors on less time tha
16. rved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_ 002 Visit Our Website www tech2tech net Page 20 5 20 5 3 Fuel Injector Current Waveforms The test that gives you the most information about the operation and condition of a fuel injector is the current test Just within the last few years current probes have become commercially available that will allow a tech to observe the current flow in small time units Current probes are presently available for under 300 that will measure current accurately in time units as small as lms Screen Capture 20 2 Screen Capture 20 2 shows the cur rent waveform of a Honda fuel injec REPLAY FILE 2 tor When monitoring the ground D i control such as in Screen Capture 20 f 1 the tech only knows that the injec tor was grounded and for how long By monitoring the current flow during this event much more can be learned Point A At point A the injector is grounded and current starts to flow Note that the current does not instantly reach maximum current flow The current climbs to the maximum flow over a 0 ae R a period of about 1 5ms i ms 9 sec ESI 9 50 ae gt The reason for this climb in current often called a current ramp is that a winding of wire will have a resistance to current rise that is in addition to the resistive value of the circuit This natural re sistance a coil of wire adds is called inductive reactance By point C the i
17. t of the circuit The induc tive reactance of the winding is no longer affecting the current flow This maxi mum current flow is controlled by the resistance of the circuit Most Honda injectors will flow about 1 5 1 8 amps Screen Capture 20 3 Point D At point D the injector ground is re D 24 REPLAY FILE 8 leased and the injector current drops to 0 and the injector closes The time dif ference between point A and point D is the PW of the injector You can clamp on each injector circuit individually to observe each injector s waveform or clamp on the injector s feed wire to observe all the injector waveforms at once Screen Capture 20 3 shows all the injectors current draw shown at once When comparing the total current draw of all the injectors it is easier to have all the patterns on the screen at once 50 ms 10 When using an amp probe you simply clamp the probe over the wire you want to measure the current in You can clamp either wire at an injector since it is the same current on either side Image 20 2 On the models with external injector resisters it is best to get the signal at the resistor block From there you can clamp each indi vidual injector or clamp on the feed wire and see all the injectors at once This setup is shown in Image 20 2 All Rights Reserved 2000 Sure Seal Products Inc This manual printed 4 9 00 from the file pgmfiobd_002 Visit Our Website www tech2tech net Pag
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