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1. c tL Schematic illustration of CDI process CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 17 Mixture formation Main injection The main injection phase regulates the engine torque and output Main injection is performed shortly after preinjection The injection pressure of up to 2 000 bar causes the fuel to be atomized very finely The resulting fuel drop lets have a large surface area in relation to their volume This both accelerates the combustion process and reduces the size of particle emissions CDI injection system 1 Fuel heating element 2 Fuel filter 3 Rail 4 Railpressure sensor 5 Pressure line Piezo injector Post iniection The CDI control unit initiates up to two post injections following on from the main injection The first post injection serves to increase the exhaust temperature which supports the conversion process for exhaust components in the oxidation catalytic converter The second post injection is performed depending on the load condition of the diesel particu late filter DPF This further increases the exhaust temperature and triggers the regeneration process in the DPF The particles in the exhaust are subsequently burnt P07 15 2007 00 High pressure pump 8 Quantity control valve 9 Pressure regulator valve gt CDI Diesel Direct Injection for OM 651 S
2. This printout will not be recorded by the update service Status 09 2008 43 44 Hall sensor Hall sensor for camshaft B6 1 The Hall sensor is located at the center of the cylinder head cover over the exhaust camshaft A permanent magnet installed in the Hall sensor creates a magnetic field The magnetic field is period ically interrupted by an orifice plate positioned on the exhaust camshaft Due to the electronics installed in the Hall sensor a voltage signal is created by the magnetic field The electronics convert the signal into a square wave signal which is evaluated by the CDI control unit Hall sensor with camshaft Together with the signal from the crankshaft position sensor the signal from the camshaft Hall sensor is used by the CDI control unit for cylinder 1 recognition If the signal from the crankshaft position sensor is not available to the CDI control unit the engine can still be started because the CDI control unit uses the signal from the camshaft Hall sensor as a substitute value emergency operation 7 04 2664 00 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Position sensor Position sensor for crankshaft L5 The position sensor is located on the transmission flange at the left on the output side The position sensor for the crankshaft is supplied with volt
3. gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Introduction Engine 651 Engine 651 incorporates a set of innovative technolo gies These include a number of new developments which cannot be found in this combination in any other series produced passenger car diesel engine Of particular importance are the piezo injectors the dual stage turbocharging and the gear drive in combi nation with a chain drive on the output side The system fully complies with the Euro 5 exhaust emissions standard using the familiar exhaust after treatment system consisting of an oxidation catalytic converter and diesel particulate filter DPF At the same time the engine output has even been increased by 20 to 150 kW with a smaller displacement and the maximum engine torque has been increased by 25 to 500 Nm Engine 651 is characterized primarily by the following innovations e Common Rail Direct Injection CDI system of the second generation from Delphi Gear drive in combination with a chain drive on the output side e Two Lanchester balance shafts integrated into one housing together with the crankshaft main bearing bridge Piezo injectors without leak oil line e Exhaust gas recirculation with a pre cooler integrated in the coolant circuit and an exhaust gas recirculation cooler with switchable bypass duct e Extended thermal management
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5. 2008 Contents Position sensor 45 Temperature sensors 46 Oil spray nozzle shutoff valve 48 Oil level check 49 Air mass and intake air 50 Pressure sensor dovvnstream of air filter 51 Intake port shutoff actuator motor 52 Throttle valve 53 Heater element 54 Condensation sensor 55 Turbocharger 56 Exhaust gas recirculation 60 Switchover valves 61 Oxygen sensor 62 Pressure sensors 63 Abbreviations 64 Index 66 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Preface Dear Reader This brochure presents the new CDI system from Mercedes Benz This system description is not specific to any partic ular vehicle and is based on the Common Rail Direct Injection CDI system of the second generation from Delphi by way of example This system description provides you with an overview of the new system on the occasion of its market launch The main purpose of this brochure is to provide technicians and fitters in the service outlets with a link between the Introduction into Service Manuals and the more detailed information in the Workshop Information System WIS and the Diag nosis Assistance System DAS In terms of content the emphasis is on presenting the operating principles and the functional relationships irrespective of the vehicle model The following aspects are covered Design and function with subsystem
6. CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Charging Boost pressure control during wide open throttle operation as of 2 800 rpm The LRK is fully open as of an engine speed of 2 800 rpm This causes almost the entire flow of exhaust gas to be fed nearly without loss to the low pressure turbine via the bypass duct and limits the level of exhaust back pressure This procedure means that the HD Lader no longer makes any contribution to increasing the boost pres sure The HD Lader has reached its choking limit This means that it can no longer generate boost pressure and in the event of further loading the turbine speed would drop off significantly In order to prevent pressure loss and additional warming of the charge air as it flows through the high pressure compressor the charge air bypass flap is opened so that the main part of the air flow is guided to the charge air cooler along a direct low loss path The wastegate is used to regulate the turbine output of the low pressure turbine in the engine performance map as required and depending on the load condition Depending on the load condition the HD Lader can build up a high level of boost pressure at low engine speeds and prevent overload of the ND Lader at high engine speeds gll ll eo N P09 40 2350 00 Schematic illustration of boost pressure c
7. Electronic selector lever module control unit N73 Electronic ignition lock control unit N80 Steering column module control unit R9 1 Cylinder 1 glow plug N10 1kM R9 2 R9 3 R9 4 X11 4 74 Y76 1 Y 6 2 Y 6 3 Y76 4 Y94 CAN B CAN C CAN D CAN E LIN C1 CDI function schematic N10 1kN P07 16 3482 00 Cylinder 2 glow plug Cylinder 3 glow plug Cylinder 4 glow plug Diagnostic connector Pressure regulator valve Cylinder 1 fuel injector Cylinder 2 fuel injector Cylinder 3 fuel injector Cylinder 4 fuel injector Quantity control valve Interior CAN Drivetrain CAN Diagnostic CAN Chassis CAN Drive LIN CDI Diesel Direct Injection for OM 651 System Description gt This printout will not be recorded by the update service Status 09 2008 11 Subsystems 12 Fuel system The fuel supply system ensures that the injection system is continuously supplied with fuel During driving operation the fuel pump pumps the fuel to the high pressure pump From there it is directed to the piezo injectors at the required pressure The fuel supply system is divided into the low pres sure system and the high pressure system Low pressure system The electric fuel pump pumps the fuel via the fuel filter and quantity control valve to the high pressure pump and from there on to the fuel pressure relief valve The quantity control valve controls the fuel volume deliv ered to the t
8. Uncontrolled electric fuel pump in fuel tank Standard as of 09 08 3 piston Chain Solenoid injectors Indirectly hydraulically actuated by voltage increase hole nozzle 18 digit 1 stage turbocharging with variable turbine geometry Electric gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Standard 2 piston Gear wheel Piezo injectors Directly electrically actuated by voltage drop 7 hole nozzle 24 digit 2 stage turbocharging with fixed geometry Pneumatic Exhaust gas recirculation pre cooler Regulation of exhaust gas recirculation EGR EGR valve type EGR bypass Coolant pump Oil pump Oil spray nozzles piston cooling Emergency operation via camshaft sensor Knock sensors Chain Crankshaft sensor System comparison Engine 646 821 EVO Engine 65 1 911 X X Electric Poppet valve Flap Pneumatically switched Uncontrolled With pneumatic shutoff Uncontrolled Controlled at clean oil side X X Cannot be shut off Can be shut off X 1 2 Dual Single Inductive sensor CDI Diesel Direct Injection for OM 651 System Description gt This printout will not be recorded by the update service Status 09 2008 Overall system CDI function schematic N14 3 B2 5b1 G2 do B4 6 Y74 B1 L5 Function schematic of Common Rail Direct Inject
9. by the update service Status 09 2008 Intake port shutoff i Intake port shutoff The intake port shutoff EKAS function uses the charge air manifold to ensure the best possible ratio between air mixing and air mass in all engine load conditions and thus an optimal fill level This optimizes the exhaust characteristics and engine output Functional principle In the charge air manifold there is a permanently open tangential intake port and a flap controlled spiral intake port for each cylinder The flaps are connected to each other by a shaft The CDI control unit controls the position of the flaps based on performance maps The spiral intake ports are closed by the flaps in the lower engine speed and engine load range and the open tangential intake ports create a high level of air mixing When the engine switches from the partial load range to the full load range the flaps in the spiral intake ports are opened according to performance maps The larger volume of air flow increases the flow rate and ensures optimal mixing of the air mixture This improves combustion and reduces the amount of particles in the exhaust in the upper load and engine speed range In the event of a fault or if the supply voltage is inter rupted the flaps in the spiral intake ports are mechan ically opened by the return springs CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the u
10. cleanliness Even the slightest contam ination can very quickly lead to engine running problems and engine damage The injection quantity depends on the fuel pressure in the rail and the duration of the actuation of the piezo injectors The rail pressure is regulated by the CDI control unit via the quantity control valve and or pressure regulating valve The injection quantity is individually computed for each cylinder by the CDI control unit based on perfor mance maps AN Safety When the engine is switched off a residual pres sure of 50 to 80 bar remains in the system For safety reasons the injection system may only be opened after the pressure has been released More detailed information on this can be found in the Workshop Information System WIS gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Fuel system P07 16 3485 00 High pressure system 1 Pressure regulating valve 4 Piezo injector 2 Rail 5 High pressure pump 3 Railpressure sensor CDI Diesel Direct Injection for OM 651 System Description gt 15 This printout will not be recorded by the update service Status 09 2008 Subsystems 16 Fuel system Rail pressure regulation The CDI control unit regulates the rail pressure via the pressure regulating valve or the quantity control valve based on performance maps Regulation vi
11. is set based on performance maps stored in the engine control unit Mixture formation with the intake air starts in the combustion chamber during the compression stroke on vehicles with CDI Fuel may be injected several times per stroke depending on the load condition of the engine The performance of the engines improved contin uously in subsequent years The direct injection and turbocharging technologies were optimized resulting in a boom in diesel vehicles which was previously unimaginable With the introduction of the 125 kW variant of engine 646 the system was able to achieve a maximum injec tion pressure of 1 600 bar and generated a maximum engine torque of 400 Nm The new engine 651 has a maximum injection pres sure of 2 000 bar and generates a maximum engine torque of 500 Nm In addition the system uses directly actuated piezo injectors which operate up to five times more quickly than the solenoid injectors used previously The injection process is divided into preinjection main injection and post injection phases to improve combustion and reduce exhaust emis sions Engine 11 With 2 2 1 displacement and 60 kW to 95 kW used from 1998 to 2003 in C Class CLK Class and E Class P01 10 2971 00 Engine 646 With 2 21 displacement and 100 kW to 125 kW used as of 2003 in C Class CLK Class and E Class P01 10 2970 00 Engine 651 With 2 2 displacement and 150 kW used as of October 2008 in C Class
12. system with coolant pump and oil spray nozzles controlled according to need e Oil pump volume controlled at clean oil side In engine measures The in engine measures and extended control func tions of the CDI control unit have allowed nitrogen NO emissions carbon dioxide CO3 emissions and fuel consumption levels to be further reduced from those of the already economical predecessor engine The following measures contribute to the improve ment e Optimized combustion chamber Lower compression ratio e Higher ignition pressure Lovver friction due to roller bearings on Lanchester balancer e Reduced inner friction i Note A detailed description of the new engine 651 can be found in the Introduction into Service Manual Order number 6516 1364 02 CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Overall system System comparison Injection pressure max High pressure regulation Fuel supply Fuel filter heater High pressure pump High pressure pump drive Quantity control valve Pressure regulating valve Fuel temperature sensor Fuel injector type Actuation Fuel injector Quantity adjustment 12C code Turbocharger type Boost pressure control Intake port shutoff Engine 646 821 EVO 1 600 bar Engine 651 911 2 000 bar Via quantity control valve and pressure regulating valve
13. the diesel particulate filter CDI Diesel Direct Injection for OM 651 System Description gt 33 This printout will not be recorded by the update service Status 09 2008 CDI control unit CDI control unit N3 9 The CDI control unit is located on the air filter housing The CDI control unit serves as an interface between The CD control unit is equlpped vvith cooling fins at the drive train CAN CAN C and the chassis CAN the bottom which project inside the air filter housing CAN E and are cooled by the intake air The engine control system is equipped with a fault The task of the CDI control unit is divided into the memory and powerful diagnostic functions for moni following subtasks toring all system components and functions This Engine torque control incorporates the following aspects e Injection control e Fault memory checking e Charging e Engine control diagnosis e Deceleration fuel shutoff e European On Board Diagnosis EOBD e Thermal management e Diagnosis via CAN bus e Exhaust gas recirculation EGR Diagnosis via K line e Exhaust treatment P15 00 2190 00 CDI control unit 1 CD control unit 3 Air filter housing 2 Cooling fins 4 Air filter 34 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Alternator Alternator G2 The alternator regulates the charging voltage depend
14. the engine is running CDI Diesel Direct Injection for OM 651 System Description gt This printout will not be recorded by the update service Status 09 2008 41 Glow output stage Glow output stage N14 3 The glow output stage is located on the end of face of the cylinder head at the front It consists of a plastic housing reinforced by an aluminum plate on the under side The CDI control unit reads in the following parameters about the engine operating condition to control the glow output stage Engine speed Load e Coolant temperature The glow output stage is actuated by the CDI control unit via Local Interconnect Network LIN Diagnostic communication between the glow output stage and the CDI control unit takes place over the same LIN connection P07 07 2075 00 Glow output stage A distinction is made between the following glowing types Preglowing For reaching the start temperature of the glow plugs more quickly e Start ready glowing Ensures that the temperature is high enough after preglowing and until the engine is started e Start up glowing Stabilizes the starting speed of the engine e Afterglowing Improves engine running after a cold start and the warm up characteristics of the engine Diagnostic glowing For system diagnosis Diesel particulate filter DPF glowing Supports regeneration e Emergency glowing Initiated in the event of problems with communicati
15. up A spring holds the nozzle needle in the nozzle seat until the piezo element is charged and has expanded Engine running No injection The rail pressure generated is applied to the nozzle needle The piezo element of the fuel injector is charged in this state A spring holds the nozzle needle in the nozzle seat The nozzle is closed Engine running Injection Voltage discharge from the piezo element causes it to shorten A travel transmission device transfers this movement to the nozzle needle The nozzle needle raises to free up the injection holes in the nozzle Injection takes place until the piezo element is recharged by the CDI control unit Engine running End of injection Voltage is applied to the piezo element to move it back to its starting position The travel transmission device transfers this movement to the nozzle needle The nozzle needle is thus pressed into the nozzle seat and seals the injection holes Engine OFF Control unit run on finished The injection system is full of fuel but is unpressurized atmospheric pressure A spring holds the nozzle needle in the nozzle seat The nozzle is closed and no injection takes place AN Warning Risk of death During operation a high voltage of up to 250 V is applied to the piezo injectors AN Warning No voltage measurements may be performed on injectors Due to the risk of engine damage no connections on the injection system may be disconnected while
16. CDI Diesel Direct Injection for OM 651 System Description M m E ANN NN M M MAL CAT Gm NN This printout will not be recorded by the update service Status 09 2008 Mercedes Benz Service CDI Diesel Direct Injection for OM 651 oystem Description Daimler AG Technical nformation and Workshop Equipment GSP OI D 70546 Stuttgart This printout will not be recorded by the update service Status 09 2008 Information and copyright Ordering workshop information All printed workshop information from GSP Ol such as Introduction into Service Manuals System Descriptions Function Descriptions Technology Guides Technical Data Manuals and adhesive labels can be ordered as follows In Germany Through our GSP l Shop on the Internet Link http gsp ti shop com or alternatively Email customer support daimler com Phone 449 0 18 05 0 10 79 79 Fax 49 0 18 05 0 10 79 78 Outside Germany Please get in touch with the contact person responsible for your market Important note We would like to advise you that our workshop information is only produced in limited editions Only the routine distribution list can guarantee a reliable supply We recommend that you check your distribution list at regular intervals Product portfolio You can also find comprehensive information on our complete product portfolio in our Internet portal Link http ope
17. Fuel filter condensation sensor with heating element B76 1 The condensation sensor is only present in vehicles with code U41 fuel water separator and lubrication package It is inserted in the fuel filter from above where it measures the water level The sensor determines the electrical resistance between the electrodes in the water level sensor If fuel lies between the electrodes the sensor does not send an output signal If the water level in the fuel filter rises up to the electrodes the electrical resistance decreases This voltage change is recorded and forwarded to the CDI control unit When there is an increased level of water in the fuel filter the CD control unit sends a message to the instrument cluster via the chassis CAN CAN E P07 04 2668 00 Fuel filter condensation sensor with heating element code U4 1 1 Integral electronics 2 Electrode 1 3 Electrode 2 4 Heating element 5 HFuel filter housing Cap for water extraction CDI Diesel Direct Injection for OM 651 System Description gt This printout will not be recorded by the update service Status 09 2008 55 i Turbocharger Dual stage turbocharger The two turbochargers are located on the right of the crankcase underneath the exhaust manifold The dual stage turbocharging system incorporates two turbo chargers of different size with a bypass control system The dual stage turbocharger enables continuous power outp
18. IMS ssed q 19 009 SES ISNCYXJ GC 4ojenjoe uome na24i284 SES jsneuX3 6 LZA OSU S MOL Jie sseui WJH JOH 6 29 eusis 10SU S ainjeiadwa we S PUD p jiunjouo2 1409 6 7 N eusis 10SU S ainjeiadwa uome no4l284 ses jsneux3 JOSU9S uoi isod jeusyueJ uoienjae uome n941994 Seg ISsneyxg 6 eusis 10SU S SINSSIIA soog Z Josues jepad 10 e 19 992y 28 819 10SU S 101115800 JJEYSYUCID 9 IPUS31S 10SU S MOL Jie sseu Ul 20H 1 ses ysneyxa 4 42 Jasaig rey uouiuio Jo 211 1 925 uonoun J vL 918 s za s 828 00 6522 02 Fld S8A 58 r LE n 8 118 L 188 31 CDI Diesel Direct Injection for OM 651 System Description gt This printout will not be recorded by the update service Status 09 2008 Subsystems 32 Exhaust system Exhaust treatment The exhaust treatment system filters a large part of the remaining pollutants still present in the exhaust gas The system consists of the familiar combination of oxidation catalytic converter and diesel particulate filter DPF The exhaust treatment system supple ments exhaust gas recirculation to intercept the following pollutants and reduce them through after treatment e Nitrogen oxides NOx Hydrocarbons HC e Carbon monoxide CO e Pollutant and soot particles Operation of oxidation catalyt
19. This printout will not be recorded by the update service Status 09 2008 59 Exhaust gas recirculation EGR actuator Y27 9 The EGR actuator is integrated on the left between the EGR bypass flap and the EGR pipe The EGR actuator regulates the exhaust gas flow in order to reduce nitrogen oxide NO emissions The CDI control unit actuates the actuator motor for EGR directly The cross section of the valve opening deter mines the exhaust volume which is recirculated into the engine intake tract via the charge air manifold The EGR actuator is integrated into the cooling circuit of the engine which protects it from thermal overload EGR path 1 EGR cooler 2 Bypass flap for EGR cooler EGR cooler The EGR cooler is located on the left in the direction of travel downstream of the EGR bypass flap The housing is made of stainless steel and coolant flows through it This reduction in temperature increases the density of the exhaust gas without increasing the number of soot particles This in turn increases the exhaust gas recir culation rate as well as lowering NO missions P14 20 2257 00 3 EGR actuator 4 Actuator motor for EGR actuator gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Switchover valves Switchover valve for EGR cooler bypass Y85 The switchover valve is located on the left
20. a the pres sure regulating valve and regulation via the quantity control valve are distinct processes Regulation via pressure regulating valve After each engine start the pressure regulating valve is actuated first whereas the quantity control valve is not actuated and remains fully open This allows the maximum quantity of fuel to be supplied to the high pressure pump Regulation via the pressure regulating valve takes place under the following conditions e After every engine start with the engine idling up to a fuel temperature of 10 C with the fuel temperature rising e After every engine start with the engine idling as of a fuel temperature of 5 C with the fuel temperature dropping One of the functions of regulation via the pressure regulating valve is to rapidly warm up cold fuel Pressing the fuel through the narrow gap in the pres sure regulating valve can heat up the fuel to over 150 C in certain conditions Regulation via quantity control valve The advantage of regulation via the quantity control valve is that the high pressure pump only has to compress as much fuel as the quantity control valve lets through to the high pressure pump based on performance maps This reduces fuel consumption and relieves the load on the high pressure pump Regulation via the quantity control valve takes place under the following conditions e The fuel temperature is above 10 C During one off rail pressure requests gr
21. age by the CDI control unit A permanent magnet is installed in the crankshaft position sensor The magnetic field it generates is periodically interrupted by the orifice plate The interruptions in the magnetic field create a voltage pulse in the built in electronics The Hall electronics convert this signal into a square wave signal which is forwarded to the CDI control unit 04 2658 00 Position sensor crankshaft 1 Crankshaft position sensor 2 Flywheel 3 Onifice plate CDI Diesel Direct Injection for OM 651 System Description gt 45 This printout will not be recorded by the update service Status 09 2008 46 i Temperature sensors Low temperature sensors Low temperature sensors consist of Negative Temper ature Coefficient NTC resistors They are made of current conducting material silicon The resistance of the low temperature sensors reduces as the temperature increases The voltage changes are forwarded to the CDI control unit where they are eval uated Coolant temperature sensor B1 1 4 The coolant temperature sensor is installed in the thermostat housing Charge air temperature sensor B17 8 The temperature sensor for charge air is located in a plastic housing in front of the throttle valve actuator Fuel temperature sensor B50 This temperature sensor records the temperature of the fuel flowing through the high pressure pump and is located next to the fuel feed lin
22. ate service Status 09 2008 Temperature sensors B2 5b1 P01 00 3116 00 Engine 651 with temperature sensors CDI Diesel Direct Injection for OM 651 System Description gt 47 This printout will not be recorded by the update service Status 09 2008 Oil spray nozzle shutoff valve Shutoff valve for oil spray nozzles Y 131 The shutoff valve for oil spray nozzles is located on the The oil spray nozzles are shut off in the post start crankcase on the left in the direction of travel phase as long as one of the following conditions is The shutoff valve shuts off the oil feed to the oil spray nozzles for piston crown cooling If it is not actuated e Engine oil temperature greater than 10 C the shutoff valve is open dnd e The max shutoff duration depending on intake air and engine oil temperature has not yet been reached Or The engine speed or the injection quantity has not yet reached a specified limit value P18 30 2136 00 Crankcase with shutoff valve 1 Shutoff valve for oil spray nozzles 48 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Oil level check Switch for oil level check S43 The switch for oil level checking is screwed on to the lower section of the oil pan on the outside The oil level in the float chamber of the switch equal izes with th
23. aust gas first enters the actual EGR path via a pre cooler The recirculated exhaust gas quantity is controlled via the EGR actuator In order to further improve the efficiency the exhaust gas is directed via the EGR cooler and cooled further depending on the performance map If the tempera ture of the incoming exhaust gas is too low the path to the EGR cooler is closed via a bypass flap and the exhaust gas is guided directly to the charge air mani fold The EGR bypass flap is actuated by the CDI control unit via a vacuum unit If some of the exhaust gas is directed past the EGR cooler the combustion chambers are warmed up more rapidly in the lower load range This means that there is less carbon monoxide CO and hydrocarbons HC in the exhaust In the upper load range the exhaust gas is directed via the EGR cooler and thus cooled This lowers the concentration of nitrogen oxides NO in the exhaust gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Exhaust gas recirculation 197 14 Jo uieaJjsuMop 40SU S BINSSAld G 9828 eusis 10SU S jeped 102819 922y Josues aJnjeJoduia wie 9 7 18 8819 19 14 118 Jo uieaJjsuMop 40suas aunssald 9 PA JOAOYDJIMS Josuas ainjesadwa uome na34r284 988 jsneuX3 vp1 918 uoljenjoe AIPA ssed q 19 009 uoie n24I994 588 Jsneux3 GBA Josuas aJnssaJd jsoog 1 98 J49A0421
24. aust gas recirculation EGR pre cooler 12 EGR actuator 13 EGR cooler 14 EGR bypass flap CDI Diesel Direct Injection for OM 651 System Description gt This printout will not be recorded by the update service Status 09 2008 Charging Boost pressure control during wide open throttle operation between 1 200 and 2 800 rpm As of an engine speed of 1 200 rpm during wide open In this state the two turbochargers work together and throttle operation the boost pressure control flap provide the required boost pressure jointly LRK is opened in the working range cross section of opening of 5 to 95 depending on the boost pres sure required The wastegate and charge air bypass flap are closed in this operating condition As the cross section of the LRK opening increases the ND Lader is continuously engaged and a greater exhaust volume flows through it The intake of clean air is further pre compressed e P09 40 2349 00 Schematic illustration of boost pressure control during wide open throttle operation between 1200 and 2800 rpm A Intake air 4 Wastegate 10 Exhaust manifold B Exhaust flow 5 Charge air bypass flap 11 Exhaust gas recirculation EGR Air filter pre cooler 1 High pressure turbocharger 7 Charge air cooler 12 EGR actuator 2 Low pressure turbocharger 8 Throttle valve actuator 13 EGR cooler 3 Boost pressure control flap LRK 9 Intake manifold 14 EGR bypass flap 28 amp
25. ction for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Charging l Boost pressure control during wide open throttle operation up to 1 200 rpm The boost pressure control flap LRK is almost closed up to an engine speed of 1 200 rpm during wide open throttle operation In this state the entire exhaust flow flows over the turbine wheel of the high pressure turbocharger HD Lader to the turbine wheel of the low pressure turbocharger ND Lader and then to the exhaust system The majority of the exhaust energy acts on the turbine wheel of the HD Lader which generates the main part of the required boost pressure Despite the low exhaust flow this produces a high boost pressure which builds up very quickly The remaining exhaust energy acts on the turbine wheel of the ND Lader which drives the compressor impeller via the supercharger shaft The ND Lader thus does not act as a hydrodynamic retarder The wastegate and charge air bypass flap are closed in this operating condition P09 40 2348 00 Schematic illustration of boost pressure control during wide open throttle operation up to 1200 rpm A Intake air B Exhaust flow 4 V astegate 6 Air filter 1 High pressure turbocharger 2 Low pressure turbocharger 3 Boost pressure control flap LRK 5 Charge air bypass flap 7 Charge air cooler 8 Ihrottle valve actuator 9 Intake manifold 10 Exhaust manifold 11 Exh
26. e of the high pressure pump Injection quantity and rail pressure are auto matically reduced as soon as the temperature of the supplied fuel exceeds 90 C Oil temperature sensor B1 The oil temperature sensor records the engine oil temperature and is located above the vacuum pump in the oil duct on the crankcase Intake air temperature sensor B2 5b 1 The intake air temperature sensor is located in the housing of the hot film mass air flow sensor High temperature sensors High temperature sensors consist of Positive Temper ature Coefficient PTC resistors They are made of metal The resistance of the high temperature sensors increases as the temperature increases The voltage changes are forwarded to the CDI control unit where they are evaluated Temperature sensor upstream of turbocharger B19 11 The temperature sensor is located on the exhaust manifold flange upstream of the turbocharger where it determines the exhaust temperature This allows the thermal load on the engine and the turbocharger to be monitored Temperature sensor upstream of diesel particulate filter B19 9 The temperature sensor is located in the assembly upstream of the diesel particulate filter DPF The sensor measures the temperature of the exhaust gas as well as the thermal load on the oxidation catalytic converter gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the upd
27. e oil level in the oil pan via a feed and drain bore in the oil level check switch and in the oil pan If enough engine oil is present the reed contact is closed by the magnetic field of the ring magnet The reed contact opens if the minimum level is dropped below The connection to the ground contact is inter rupted and a warning message is displayed on the instrument cluster P18 40 2339 00 Oil level check 1 Oil level check switch 2 Upper section of oil pan 3 Lower section of oil pan i Note Temporary level fluctuations are balanced out by the volume of the housing and the size of the drain bores of the oil level check switch This prevents unnecessary warning messages from occurring e g when cornering CDI Diesel Direct Injection for OM 651 System Description gt 49 This printout will not be recorded by the update service Status 09 2008 Air mass and intake air Hot film mass air flow sensor B2 5 Intake air temperature sensor B2 5b1 The hot film mass air flow sensor HFM is located in The temperature sensor is located in the same the intake manifold behind the air filter The HFM housing as the HFM and is a NTC resistor records the actual air mass flow rate very precisely The heated sensor element in the HFM is cooled more rapidly as more air flows past The heating current required to maintain the temperature of the sensor element is used as an indicator for the air mass flowing past In
28. eater than 310 bar e g when starting off When the engine is switched off the quantity control valve interrupts the fuel supply to the pump elements gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Mixture formation Injection control The injection control system defines the injection timing point and the injection period The injection quantity depends on the rail pressure and injection period The piezo injectors which are directly actuated by the CDI control unit allow the fuel injection process to be more precisely adapted to the respective situation in terms of load and rpm Depending on the injection timing point the injection phase is referred to as preinjection main injection or post injection Preinjection With preinjection a small quantity of fuel is injected into the cylinder before the actual main injection phase starts This procedure takes place up to two times This improves the efficiency of combustion and produces a smoother combustion cycle due to the heating of the combustion chamber This results in lower exhaust emissions and less combustion noise The CDI control unit calculates the preinjection quan tity and the start of piezo injector actuation depending on the following factors Load condition of the engine e Start of actuation of last main injection u rf
29. fter a cold start and the warm up characteristics of the engine The CDI control unit evaluates the engine oil tempera ture and actuates the glow plugs via the glow output stage after the engine is started Afterglowing is termi nated once the coolant temperature reaches a speci fied value i Note If a fault occurs in the preglow system glow plugs or lines this is indicated by the preglow indicator lamp and the fault is also stored in the fault memory of the CDI control unit gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Glow system Diagnostic glowing This function is used for diagnosis of the individual glow circuits The glow plugs are actuated at a low temperature level so that system faults can be detected and stored in the fault memory of the CDI control unit Diagnostic glowing is used for troubleshooting and allows a system test to be performed irrespective of the engine oil temperature Diagnostic glowing is also performed automatically by the system when the preglow system has not been active for an extended period of time e g no glowing procedure activated due to high coolant temperatures Diesel particulate filter glowing Diesel particulate filter DPF glowing is only performed during DPF regeneration to increase the load and stabilize combustion Emergency glowing The emergency glowing function
30. ic converter schematic 1 Catalyst support 113 74 Intermediate layer Function sequence of exhaust treatment The exhaust gases emitted by the engine are cleaned in an oxidation catalytic converter and a diesel partic ulate filter DPF The oxidation catalytic converter reduces the concen tration of hydrocarbons HC and carbon monoxide CO and generates the required thermal energy for the DPF regeneration phase through afterburning The DPF comprises a ceramic honeycomb filter element made of silicon carbide and coated with platinum The exhaust gas which is precleaned in the oxidation catalytic converter flows into the channels of the DPF which open out towards the front and reaches the channels which open out to the rear through the porous filter walls of the honeycomb filter body The soot particles are held in the honeycomb filter of the DPF The cleaned and filtered exhaust is then dissi pated through the exhaust system P14 40 2384 00 HC Hydrocarbon 2 Insulating mat vvashcoat H0O Water 3 Housing CO Carbon monoxide N Nitrogen 111 4 Ceramic monolith CO Carbon dioxide NO Nitrogen dioxide gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Exhaust system E o ud o DPF regeneration y Q The DPF differential pressure sensor reports the load The regeneration times are dependent on temperature 3 e o c
31. ing on electrical consumption and the battery charge level The CDI control unit regulates the alter nator output via an alternator interface This has the effect of for example reducing the engine idle speed and exhaust emissions The alternator detects various faults and reports them in turn to the CDI control unit Communication between the CDI control unit and the alternator takes place over the Local Interconnect Network LIN bus P15 40 2527 00 Alternator CDI Diesel Direct Injection for OM 651 System Description gt 35 This printout will not be recorded by the update service Status 09 2008 High pressure pump The 2 piston high pressure pump is located on the left hand side of the crankcase at the output side The high pressure pump compresses the fuel and gener ates the required rail pressure The gear wheel of the high pressure pump is driven by the gear drive at half of the crankshaft rpm The torque is transferred to the shaft of the high pressure pump via a multi gear driver ul j ALG 07 02 2119 00 High pressure pump 1 Return flow 4 Fuel temperature sensor 2 Quantity control valve 5 Gear wheel 3 Feed Multi gear driver i Note The high pressure lines between the high pressure pump the rail and the piezo injectors may only be used once 36 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by
32. ion CDI starting starter control 1 Instrument cluster message 17 Fuel injectors actuation 2 Circuit 50 status 18 Hot film mass air flow sensor signal 3 Starter actuation 19 Intake air temperature sensor signal 4 Combustion engine circuit 87 relay actuation 20 Oil temperature sensor signal 5 Preheat request Glow plugs actuation A1 Instrument cluster 7 Fuel pump relay actuation A8 1 Transmitter key 8 Engine control diagnosis communication B1 Oil temperature sensor 9 Circuit 61 status B2 5 Hhotfilm mass air flow sensor 10 Electronic selector lever module control unit status B2 5b1 Intake air temperature sensor 11 Camshaft Hall sensor signal B4 6 Rail pressure sensor 12 Coolant temperature sensor signal 6 1 Camshaft Hall sensor 13 Crankshaft position sensor signal B11 4 Coolant temperature sensor 14 Rail pressure sensor signal GZ Alternator 15 Pressure regulating valve actuation 16 Quantity control valve actuation 10 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 N10 2kD m L5 Crankshaft position sensor M1 Starter M3 Fuel pump N3 9 CDI control unit N10 1 Front SAM control unit with fuse and relay module N10 1kM Circuit 50 relay starter 10 1 Circuit 87 relay engine N10 2 Rear SAM control unit with fuse and relay module N10 2kD Fuel pump relay N14 3 Glow output stage N15 5
33. ion for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Fuel system P07 16 3484 00 Low pressure system 1 Pressure regulating valve Suction jet pump 2 Rail 7 Fuel strainer 3 Railpressure sensor 8 Swirl pot 4 High pressure pump 9 Fuel pump 5 Fueltank CDI Diesel Direct Injection for OM 651 System Description gt 13 This printout will not be recorded by the update service Status 09 2008 Subsystems 14 Fuel system High pressure system The high pressure system generates and stores the fuel pressure required for injection The fuel is supplied to the rail by the high pressure pump in a controlled manner The fuel reaches the individual piezo injectors at a maximum injection pressure of up to 2 000 bar via the high pressure lines In addition the high pressure system operates without a leak oil line High pressure regulation The high pressure pump compresses a certain quan tity of fuel depending on the signal from the acceler ator pedal sensor and the engine speed The actual fuel pressure and fuel temperature in the rail are recorded by the rail pressure sensor and fuel temper ature sensor and continuously forwarded to the CDI control unit A Component damage When working on the high pressure system e g rail pressure lines high pressure pump fuel injec tors it is important to pay particular attention to quality and
34. is activated for 180 s if a problem occurs with communication via the Local Interconnect Network LIN bus e g in the event of open circuit or short circuit The emergency glowing function is also activated for 180 s if communication fails during the glow procedure for longer than 250 ms The glow duration and glow voltage are then based on substitute values Preglow indicator lamp The preglow indicator lamp in the instrument cluster lights up during the glow procedure and indicates faults in the glow system CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 23 Glow system NIT PAL NVI SISSey Bnd MOS p 00 0892 9 04 9091 LO NIT 3 7 64 Bnd MOJ8 Bnd MOJ8 Z 12pU ko snd Mojs JIUN J04ju02 yoo uonlusi 21u04129 3 98875 ndino Mo D 64 Z 64 1 64 EZLN E PIN Hun 04ju02 142 6 EN SMIS 19 9 40 eu483 v 20 uoijenjae duie 10je2ipul MoJ894Jd G Josuas aJnjeJeduio IQ 19 uonpn op s njd MO y Aay 19gusueJ 1 8V sanbal moj Awe J1OJ29 PUI MO 8Ald 9191 Y eusis 10SU S aImeladua Z 19358n 9 juauinJjsu LV sniejs 0G N2419 2 4142 299 11q 1154 uouruio Jo 2rnjeuiauos uomounj gt CDI Diesel Direct Injection for OM 651 System Description 24 This printout will not be recorded
35. isolator bushing Outer protective tube Inner protective tube PX GK amp NS gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Pressure sensors Differential pressure sensor on DPF B28 8 The differential pressure sensor of the DPF is located on the right of the cylinder head on the rear bracket for the air filter The sensor consists of the following components Pressure sensor element Electronics for signal amplification The differential pressure sensor records the exhaust pressure upstream of and downstream of the DPF via the exhaust pressure lines and thus determines the pressure differential This pressure differential acts on the pressure sensor element which produces a voltage which is forwarded to the CDI control unit BOSCH B 261 260 EZEDIN Mide in Erimpiy m mr Ay t bra P07 04 2667 00 Differential pressure sensor Exhaust back pressure sensor B60 The sensor is located at the left rear on the EGR pipe A metallic separating diaphragm with plunger acts on the sensor membrane when pressure is applied The pressure dependent resistors on the sensor membrane cause the resistance to change when the membrane is deflected This value is forwarded to the CDI control unit as a voltage signal which uses it to calculate the exhaust back pressure This pressure information is used b
36. ity control valve regulates the fuel quantity can take place between the high pressure side and supplied to the pump elements via the annular low pressure side passage The CDI control unit regulates the coil current via a The quantity control valve has the following tasks pulse width modulated signal to produce a magnetic force This process causes the valve pin to press against the balls thus creating an equilibrium of force against the high pressure side The diverted fuel flows back into the fuel tank via the fuel return connection on the rail Regulation of the fuel flow to the pump elements of the high pressure pump e Interrupt fuel feed to pump elements of high pressure pump when engine is switched off P07 05 2065 00 05 2064 00 Pressure regulator valve Quantity control valve CDI Diesel Direct Injection for OM 651 System Description gt 39 This printout will not be recorded by the update service Status 09 2008 Piezo injector The piezo injectors Y76 inject the highly pressurized fuel into the respective cylinders The injection quan tity depends on the duration of actuation the pressure present and the opening closing speed of the injector In contrast to previous fuel injectors the new piezo injectors do not inject upon a voltage increase but upon a voltage drop Function A discharge of voltage causes the piezo element to shorten This movement is transferred to the no
37. n aftersales daimler com Questions and suggestions If you have any questions or suggestions concerning this product please write to us E mail customer supportEdaimler com Fax 49 0 18 05 0 10 79 78 or alternatively Address Daimler AG GSP OIS HPC R822 W002 D 70546 Stuttgart 2008 by Daimler AG This document including all its parts is protected by copyright Any further processing or use requires the previous written consent of Daimler AG Department GSP OIS HPC R822 W002 D 70546 Stuttgart This applies in particular to reproduction distribution alteration translation microfilming and storage and or processing in electronic systems including databases and online services Image no of title image PO 1 00 3120 00 Order no of this publication 6516 1363 02 08 2008 This printout will not be recorded by the update service Status 09 2008 Contents Preface 5 Introduction 6 System comparison 8 CDI function schematic 10 AR 4 Fuel system 12 Mixture formation 17 Glow system 22 Intake port shutoff 25 Charging 26 Exhaust gas recirculation 30 Exhaust system 32 ea Y CDI control unit 34 Alternator 35 High pressure pump 36 Rail 38 Rail pressure control valves 39 Piezo injector 40 Glow output stage 42 Glow plugs 43 Hall sensor 44 CDI Diesel Direct Injection for OM 651 System Description gt This printout will not be recorded by the update service Status 09
38. n quantity correction This function corrects the main injection quantity using the oxygen sensors upstream of the catalytic converter The injection quantity is changed until the specified lambda value stored in the CDI control unit is reached CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Subsystems Mixture formation P07 16 3481 00 e B4 6 E m B17 8 N3 9 Za B14 B19 11 B37 B2 5 5 D D gt gt gt gt 20 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Mixture formation 40328ful y 4 bul 2 J0399 U1 4 pul 2 40328ful Z 4 pul 2 40328fui 19puI ko HUN 04209 GOD Josuas uoijisod 3jeusyue12 193194409 21 5259 Jo weassdn 40suas uas xg A1ajjeg U1 S S 601110 p4POQ UQ OSU S aJnjeJeduia any Josuas Jepad 107e19 992Y Jda 40sues eunssaud en uala ag 19818490Q n3 Jo uieaJjsdn Josuas ainjesadwa 199 14 ajejnoipied jasaip Jo weassdn Josuas JOSUAS aJnjeJeduioa Jie ABICY OSU S aJnjeJeduia pisino Josuas aJnjeJeduia Juejooy Josuas aJnssaJd 1soog Josuas aJnssaJd Ie OSU S aJnjeJeduia se 9ye7u F 974 ES 9 4 Z OLA 9 6 EN GT 2 68 19
39. nator B Boost pressure control Boost pressure sensor C Camshaft Hall sensor CDI control unit Charge air bypass flap Charging Choking limit 777 Condensation sensor in fuel filter D Diagnostic glowing Diesel particulate filter glowing Differential pressure sensor on DPF DPF regeneration E EGR actuator EGR cooler EKAS actuator motor Emergency glowing Exhaust back pressure sensor Exhaust gas recirculation Exhaust system 22 35 26 93 44 34 59 26 29 55 23 23 63 33 60 60 92 23 63 30 32 Exhaust treatment F Fuel preheating system heating element G Glow output stage Glow plugs Glow system H High pressure pump High pressure system Hot film mass air flow sensor I2C coding In engine measures Injection quantity correction Instant Start System Intake air temperature sensor Intake port shutoff L Low pressure system Low pressure turbocharger boost pressure sensor M Main injection Main injection quantity correction gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 32 99 42 43 22 36 14 90 40 19 22 90 25 12 99 18 19 Index N S NIC 46 Start ready gloving 22 Start up glowi
40. ng 22 O Switchover valve Oil level check 49 Charge air bypass 59 Oxygen sensor 62 Coolant pump 61 EGR cooler bypass 61 T Piezo injector 40 u Temperature sensor Position sensor for crankshafts 45 l Charge 46 Post injection 18 Coolant L 46 Preglow indicator lamp 23 52 97 Preslowi 22 Intake air 46 E ee Ye Oil temperature 46 Preinjection 17 Upstream of DPF 46 Pressure regulating valve 39 Upstream of turbocharger 46 Pressure transducer Throttle valve actuator 53 Boost pressure control flap 58 Turbocharger 56 VVastegate control 58 PIG yox um ox ares dass 46 M Vent line heating element 54 Q Quantity control valve 39 Z Zero quantity calibration 19 R RA Rail pressure regulation 16 Rail pressure sensor 38 CDI Diesel Direct Injection for OM 651 System Description gt 67 This printout will not be recorded by the update service Status 09 2008
41. of the crankcase The position of the EGR cooler bypass flap open or closed is controlled by means of vacuum depending on the exhaust temperature When the bypass flap is open recirculated exhaust gas flows via the EGR cooler In the rest position air is admitted between the vent connection atmosphere and the vacuum unit and the bypass flap closes the bypass duct Switchover valve Switchover valve for coolant pump Y 133 The switchover valve is located at the front of the engine on the left of the throttle valve actuator The position of the regulating valve open or closed in the coolant pump is controlled by the switchover valve of the coolant pump When the regulating valve is open the coolant can circulate in the coolant circuit In the rest position the regulating valve is open The coolant pump is switched off during a cold start for max 500 s if the following conditions are fulfilled e The limit values stored in the control unit for intake air and coolant temperature and for the total fuel injection quantity have not yet been reached he engine speed or injection quantity has not exceeded the specified limit value Heat has not been requested by the automatic air conditioning control and operating unit P20 10 2254 00 CDI Diesel Direct Injection for OM 651 System Description gt This printout will not be recorded by the update service Status 09 2008 61 Oxygen
42. on over the Local Interconnect Network LIN bus gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Glow plugs Ceramic glow plugs R9 A e isk of engine damage Engine 651 features glow plugs with a ceramic glow Safety information for handling ceramic glow pin plugs Ceramic glow plugs reach a glow temperature of e Only use glow plugs from unopened original approx 1 300 C which is approx 200 C higher packaging than that of conventional glow plugs and they are also e If aglow plug is dropped on the floor it must less acceptable to drops in glow temperature over not be used their service life Important Engine damage can occur because Properties of ceramic glow plugs glow plugs are very sensitive to shock Hairline cracks may develop in the ceramic element As a consequence parts may become detached and drop into the combustion chamber while the engine is running Always handle glow plugs with the utmost care he glow plugs must be removed before removing the cylinder head and must not be reinstalled until the cylinder head has been installed e Lower energy consumption e Outstanding starting characteristics e Rapid temperature increase e High conductivity e High glow temperature e Long service life P15 20 2181 00 Ceramic glow plug CDI Diesel Direct Injection for OM 651 System Description gt
43. ondition of the DPF to the CDI control unit If theload and decrease significantly as the exhaust gas temper of soot particles is too great and exceeds a limit value ature rises The following measures are used to stored in a performance map the CDI control unit increase the exhaust temperature initiates the regeneration phase when the load condi TE M ae k b Postinjection Sula Net 4 0 e Exhaust gas recirculation vvith intake air throttling cally increasing the exhaust gas temperature DPF glow function p m During regeneration the exhaust temperature is moni ux 57 525 y tored by the temperature sensor upstream of the 9976 of soot particles are reduced The residual ash 0 nne turbocharger and the temperature sensor upstream of which is produced remains in the DPF the DPF Li Note Li Note If DPF regeneration is interrupted as a result of If the DPF is overloaded with ash the engine diag short distance trips the process is spread out nosis indicator lamp on the instrument cluster over several driving cycles Until the specified indicates that the DPF requires maintenance 7 7 Following the regeneration phase the CDI control m unit registers the calculated difference in pressure Regeneration occurs unnoticed by the customer via the DPF differential pressure sensor and compares this value vvith a reference value From this the CDI control unit determines the residual ash load of
44. ontrol during wide open throttle operation as of 2800 rpm A Intake air B Exhaust flow 4 Wastegate 6 Air filter 1 High pressure turbocharger 2 Low pressure turbocharger 3 Boost pressure control flap LRK 5 Charge air bypass flap Charge air cooler 8 Ihrottle valve actuator 9 Intake manifold 10 Exhaust manifold 11 Exhaust gas recirculation EGR pre cooler 12 EGR actuator 13 EGR cooler 14 EGR bypass flap CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Subsystems 29 Subsystems 30 Exhaust gas recirculation General The exhaust system ensures that the legally required exhaust emission limits are met The exhaust system of engine 651 combines two tech nologies for emission reduction Exhaust gas recircu lation EGR reduces emissions of nitrogen oxide NO and exhaust treatment reduces the emission of hydro carbons HC and soot particles Exhaust gas recirculation With exhaust gas recirculation EGR part of the exhaust flow is guided through the EGR path to the charge air Exhaust gas recirculation lowers the combustion temperature and the proportion of excess oxygen 02 is reduced This measure reduces the production of NO during combustion In addition the lack of oxygen reduces the combustion velocity and the exhaust flow to the oxidation catalytic converter is reduced The recirculated exh
45. pay atten tion to the respective color coding of the vacuum line and vacuum unit gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 dey ssed q ule po juauysnipe dey ssed q se as1eyo q n dey ssed q Jie as1eyo 8 00 1522 0 60d 921 9211 421 Vcl EC VOLL OLL pos jueugsn pe ajesajse y 221 un uinnoeA ajegajsey 121 l VM euiqunj 1 0 0Z1 J jj du 1055940 100 19PET AN 1 021 4 1 4e84euooqun aunssaJd M07 021 dejj o 3uo9 1 69 1soog 11 021 221 21021 dej Jo41uoo eunssaud sooq juaunsn py 211 221 deg 011 02 eunssaJd 19000 un ulnn bA 111 294M euiqun 19pei GH 2 01 Jejjeduui JOSsaidwod 1 1 011 4 1 4e81euooqun INSS Id YSIH 011 pIoJlueu Jsneux 801 SuiS4eu2oqunj 15 eng CLL LLL 57 CDI Diesel Direct Injection for OM 651 System Description gt This printout will not be recorded by the update service Status 09 2008 i Turbocharger Pressure transducer for m boost pressure control flap Y93 Note The CDI control unit transmits a pulse width modu The pressure transducer for the boost pressure lated signal to the pressure transducer The control flap is located at the rear on the left above the res
46. pdate service Status 09 2008 25 Charging General On engine 651 charging is performed via a dual stage turbocharging process Depending on the operating phase the engine is provided with the required boost pressure through the interaction of a high pressure turbocharger HD Lader and a low pressure turbo charger ND Lader This increases the cylinder charge and thus the engine output and engine torque With exhaust gas turbocharging the flow energy of the exhaust gases is used to drive the two charge air turbines The boost pressure is regulated via the boost pressure control flap LRK the wastegate and the charge air bypass flap The control operations take into account the respective engine torque request based on perfor mance maps Turbocharger 1 Vacuum unit 2 Exhaust inlet 3 Bypass 4 Charge air hose connection Function sequence of boost pressure control For a better overview of how dual stage turbocharging works three different states of wide open throttle operation have been selected These states will be used to explain and illustrate the exact process The following boost pressure control states are described Wide open throttle operation up to 1 200 rpm Wide open throttle operation between 1 200 and 2 800 rpm e Wide open throttle operation as of 2 800 rpm P09 40 2347 00 5 HD Lader Charge air inlet 7 ND Lader 8 Exhaust outlet gt CDI Diesel Direct Inje
47. pective pressure transducer regulates the flap throttle valve actuator positions via the vacuum units cross section of opening 5 to 95 VVastegate control pressure transducer Y31 4 The pressure transducer for vvastegate control is located at the right front on the cylinder head P14 20 2256 00 Pressure transducer 58 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Turbocharger Charge air bypass flap switchover valve Y132 The charge air bypass flap switchover valve is located at the front on the cylinder head The flap position cross section of opening 5 to 95 is controlled by means of vacuum If the bypass flap is not actuated air is admitted between the vent connection atmosphere and the vacuum unit The charge air bypass flap thus seals the bypass duct Low pressure turbocharger boost pressure sensor B5 4 The low pressure turbocharger ND Lader boost pres sure sensor is located on the left next to the hot film mass air flow sensor on the cylinder head The boost pressure sensor records the boost pressure generated by the ND Lader The boost pressure causes a measuring diaphragm with strain resistors to deform The resulting changes in resistance cause changes in voltage These are evaluated by the CDI control unit CDI Diesel Direct Injection for OM 651 System Description
48. rge air pressure is built up a measuring diaphragm deforms by a defined value which is processed by the CDI control unit as a change in resis tance 1 c uo cL 3 Throttle valve actuator CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 53 Heater element Heating element for vent line R39 1 The heating element is located at the end of the vent line which is installed on the clean air line to the low pressure turbocharger This heating element prevents the crankcase ventilation system from freezing up The heating element consists of a plastic housing with an integrated heating resistor The CDI control unit switches the heating element on or off depending on the outside temperature P01 20 2234 00 Y Heating element for vent line 54 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Condensation sensor Fuel preheating system heating element R54 The fuel preheating system heating element is located in the fuel filter housing There is a heating element in the fuel filter to ensure that the fuel can flow through the lines even when the outside temperature is very low The heating element is supplied with power by the signal acquisition and actuation module SAM
49. s e Relationships between the components in the system e Interaction between the system and its compo nents The system description is not intended as a basis for repair work or for the diagnosis of technical problems For such needs the Workshop Information System WIS and the Diagnosis Assistance System DAS are available as usual We will publicize modifications and new features in the relevant WIS documents only The information presented in this system description may therefore differ from the information published in the WIS All of the technical data and details in this brochure are valid as of the copy deadline in August 2008 and may therefore differ from the current production configuration Daimler AG Technical Information and Workshop Equipment GSP OI CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Introduction History of CDI diesel engines The first common rail diesel direct injection system which was introduced in the Mercedes Benz C 220 CDI OM 61 1 in 1998 finally allowed the diesel engine to establish itself in the luxury class The common rail system installed at the time achieved a maximum injection pressure of 1 350 bar On vehicles with Common Rail Direct Injection CDI the fuel is injected directly into the combustion chamber under high pressure The quantity of fuel that is injected
50. sensor The wideband oxygen sensor 63 2 is a planar multi layer two cell limit current sensor with oxygen pump cell It integrates several functions based on its modular design The planar wideband oxygen sensor contains two voltage jump sensors made of zirconium dioxide ZrO one as a sensor cell and one as an oxygen pump cell The two cells are arranged so that there is a minimal diffusion gap approx 10 to 50 um between them The diffusion gap acts as a measuring chamber and is connected to the exhaust gas via an intake opening The measuring cell has a reference air duct which is connected to the atmosphere Since the conductivity of the ceramic sensor body is temperature dependent the optimal operating temperature of the wideband oxygen sensor is approx 00 C to 800 C The temperature of the ceramic sensor body is constantly kept at approx 780 C bya heating element P07 04 2662 00 Mode of operation of pump cell Oxygen ions can be caused to move by applying a voltage to the solid electrolytes of the voltage sensor pump current The direction of the ion movement depends on the polarity of the voltage applied Mode of operation of sensor cell The sensor cell operates on the principle of a voltage jump sensor It determines the residual oxygen content O5 in the exhaust gas Design of wideband oxygen sensor Sensor element Upper isolator bushing Sealing package Sensor housing Lower
51. t Depending on how it is actu ically opened by the return springs ated by the CDI control unit the actuator motor for EKAS changes the position of the flaps in the spiral intake ports of the charge air manifold via an adjust ment lever A potentiometer serves as an angle sensor allowing comparison of specified actual values for the position of the adjustment lever NE a C P d A k h TESA x 1 11 P d i P 1 s 1 NS Intake port shutoff 1 Actuator motor 4 Tangential intake port 2 Adjustment flap 5 Charge air manifold 3 Spiral intake port 52 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Throttle valve Throttle valve actuator M16 6 The throttle valve actuator is located on the left of the engine underneath the charge air manifold The throttle valve actuator is actuated by the CDI control unit via a pulse width modulated signal The throttle valve actuator influences the air volume fed to the engine and the mixing ratio of charge air and recir culated exhaust gas mixed in downstream of the throttle valve The throttle valve is closed when the engine is switched off Throttle valve 1 Boost pressure sensor 2 Throttle valve Boost pressure sensor B5 1 The boost pressure sensor is located on the left of the engine downstream of the throttle valve actuator When the cha
52. tegrated electronics evaluate this measurement data making it possible to precisely determine the air volume flow rate Only a part of the air mass flow is recorded by the sensor element The overall air mass flowing through the measurement pipe is determined based on a data model P07 07 2075 00 Air filter housing 1 Hot film mass air flow sensor 50 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Pressure sensor downstream of air filter The pressure sensor B28 5 is located on the clean air line downstream of the air filter housing and is tasked with recording the vacuum in the intake tract When the air pressure is built up a measuring diaphragm with strain resistors is deformed The resulting changes in resistance cause changes in voltage These are evaluated by the CDI control unit P07 04 2660 00 Clean air line on air filter 1 Pressure sensor downstream of air filter CDI Diesel Direct Injection for OM 651 System Description gt 51 This printout will not be recorded by the update service Status 09 2008 Intake port shutoff actuator motor The actuator motor for intake port shutoff EKAS In the event of a fault or if the supply voltage is inter M55 is located above the charge air manifold at the rupted the flaps in the spiral intake ports are mechan output side on the lef
53. ter glowing is performed in steps via the controllable glow temperature The CDI control unit regulates the voltage at the glow plugs via the glow output stage depending on time and temperature This has the following advantages e Short preglow time e Stable idling ow exhaust gas emissions e Good response behavior Controllable glow temperature Preglowing Preglowing warms up the combustion chambers of the engine so that the required ignition temperature of the fuel air mixture is reached The CDI control unit first evaluates the engine oil temperature and then actu ates the glow output stage via the drive LIN LIN C1 depending on the coolant temperature A prerequisite for the preglow is a coolant tempera ture below 30 C Start ready glowing The start ready glow function provides a sufficiently high temperature after preglowing until the engine is finally started To achieve this the glow output stage actuates the glow plugs The preglow indicator lamp goes out once a start ready temperature of 1 250 C is reached in the glow plug Start up glowing start up glowing stabilizes the starting speed of the engine When the CDI control unit receives the infor mation Circuit 50 ON from the electronic ignition lock control unit the glow output stage actuates the glow plugs via the drive LIN thus supporting the first firing strokes and engine start up Afterglowing Afterglowing improves engine running a
54. the update service Status 09 2008 High pressure pump High pressure side High pressure generation The eccentric shaft 3 with its crank disk 2 moves The leading edge of the eccentric shaft causes the the pistons 6 up and down against the respective piston to move upwards This compresses the fuel piston springs 7 This fills the piston picture A and picture B The valve separates the fuel being enables the fuel to be compressed compressed from the fuel feed If the fuel pressure in the cylinder rises above the pressure inside the high pressure system the ball valve opens and the fuel is Piston filling directed into the high pressure system The piston is pressed downwards by the tensioned piston spring 7 The fuel supplied enters the annular passage and then the cylinder via a valve 9 A defined force must be applied to the valve spring 5 in the process The ball valve 8 prevents the fuel from flowing back from the high pressure channel 1 into the pump elements P07 02 2120 00 Schematic diagram 1 High pressure channel 8 Ballvalve 2 Crank disk 9 Valve 3 Eccentric shaft 4 Fuel feed to high pressure elements A Piston filling 5 Valve spring B High pressure generation 6 Piston Piston spring CDI Diesel Direct Injection for OM 651 System Description gt 37 This printout will not be recorded by the update service Status 09 2008 Rail Rail The rail is on the left ne
55. ut without the familiar problem of turbo lag An overview of the most important advantages e A pronounced and high torque curve e ncrease in rated output combined with lowering of rated speed mproved boost pressure curve e Reduced fuel consumption Reduction in nitrogen oxide NO emissions Long service life and high reliability Operating principle The exhaust gas flowing from the cylinders first flows into the exhaust manifold From here the exhaust flow can either be directed via the high pressure turbo charger HD Lader or it can be diverted via the bypass line to the low pressure turbocharger ND Lader The exhaust flow is directed to the HD Lader or ND Lader depending on the position of the boost pressure control flap LRK The position of the LRK is regulated by the CDI control unit based on performance maps The initial boost pressure buildup is mainly generated by the HD Lader but afterwards the boost pressure is increasingly built up by the ND Lader If the HD Lader reaches its output limit boost pres sure buildup is performed by the ND Lader alone In this case the charge air bypass flap opens and the compressed charge air from the ND Lader is directed past the compressor housing of the HD Lader The boost pressure is limited by the wastegate i Note The vacuum units and adjustment rods of the respective flaps and of the wastegate can be replaced When installing vacuum lines always
56. wo pump elements of the high pressure pump via the annular passage When the quantity control valve is closed decelera tion mode fuel from the fuel feed line is sent directly into the annular passage via the zero delivery throttle to lubricate the pump elements The fuel pressure present at the quantity control valve is limited to 4 0 4 5 bar by the fuel pressure relief valve If this value is exceeded the fuel pressure relief valve opens and directs the surplus fuel back to the fuel tank via the return line The fuel pressure relief valve also redirects a portion of the fuel to the eccentric shaft for lubrication purposes If there is air in the fuel the air is directed to the return line of the high pressure pump via the fuel pressure relief valve thus bleeding the low pres sure system To improve the efficiency of the engine and to keep the temperature of the fuel low the quantity control valve regulates the flow of fuel to the high pressure pump There is a heating element in the fuel filter to ensure that the fuel can flow through the lines even when the outside temperature is very low The heating element is supplied with power by the front signal acquisition and actuation module SAM i Note If the supplemental restraint system control unit transmits a crash signal to the CDI control unit actuation of the fuel pump is immediately inter rupted and the system is depressurized gt CDI Diesel Direct Inject
57. xt to the cylinder head and stores the fuel at the required injection pressure The stored fuel volume also acts as a damper for pressure oscillations created by the pulsating fuel supply of the high pressure pump and the short term high fuel extraction rate during injection The rail performs the following tasks High pressure reservoir Distribution of fuel to piezo injectors Pressure regulation via pressure regulating valve and rail pressure sensor Rail and rail pressure sensor 1 Pressure regulating valve 2 Rail 3 Railpressure sensor Rail pressure sensor B4 6 The rail pressure sensor is screwed directly into the rail and records the current rail pressure The rail pressure causes a measuring diaphragm with strain resistors to deform The resulting changes in resistance cause changes in voltage These are evalu ated by the CDI control unit 03 2241 00 gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Rail pressure control valves Pressure regulating valve Y74 Quantity control valve Y94 The pressure regulating valve is screwed into the rail The quantity control valve is located directly on the on the output side high pressure pump If the pressure regulating valve is not actuated it is Based on the signal from the CDI control unit the hydraulically opened so that pressure compensation quant
58. y the CDI control unit to protect the turbocharger and the engine P14 20 2261 00 Exhaust back pressure sensor CDI Diesel Direct Injection for OM 651 System Description gt This printout will not be recorded by the update service Status 09 2008 63 64 Abbreviations AGR Exhaust Gas Recirculation EGR CAN Controller Area Network CDI Common Rail Direct Injection CO Carbon monoxide CO Carbon dioxide DAS Diagnosis Assistance System DPF Diesel Particulate Filter DPF EKAS Intake port shutoff EOBD European On Board Diagnosis HC Hydrocarbons HD Lader High pressure turbocharger HFM Hot film mass air flow sensor Water gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Abbreviations 12C NOx Improved Individual Injection Correction Nitrogen oxide LIN NTC Local Interconnect Network Negative Temperature Coefficient LRK O Boost pressure control valve Oxygen N PTC Nitrogen Positive Temperature Coefficient ND Lader SAM Low pressure turbocharger signal aquisition and actuation module NO WIS Nitrogen dioxide Workshop Information System CDI Diesel Direct Injection for OM 651 System Description 65 This printout will not be recorded by the update service Status 09 2008 66 om A Afterglowing Alter
59. ystem Description This printout will not be recorded by the update service Status 09 2008 Injection quantity correction The friction produced during opening and closing of the piezo injectors causes wear on the nozzle seat of the nozzle needle This changes the injection quantity over the service life which is compensated for by correcting the actuation duration Injection quantity correction comprises the following e Zero quantity calibration Main injection quantity correction The following function requirements are required for this Engine speed between 1 000 and 2 600 rpm Deceleration mode or driving operation greater than zero e Engine oil temperature greater than 80 C Mixture formation Zero quantity calibration In order to counteract the change in the injection quantity the actuation duration of the fuel injectors can be corrected via zero quantity calibration On engine 651 with the Delphi injection system correc tion is performed with the help of two knock censors At defined intervals during engine operation or in deceleration mode a preinjection quantity is cali brated for each cylinder individually Based on the shortest possible actuation duration the actuation duration is increased until the CDI control unit receives a signal from both knock sensors The differ ence between the determined and the nominal actua tion duration is used for injection quantity correction Main injectio
60. zzle needle of the nozzle module via a travel transmission device coupler module This raises the nozzle needle to free up the injection holes Injection is stopped when the piezo element is recharged by the CDI control unit The piezo element re extends when charged The nozzle needle is lowered and the injec tion holes are resealed With Circuit 16 OFF and with CDI control unit run on over the nozzle needle is returned to its starting position by a spring so that the injection nozzles are again sealed I2C coding On engine 651 with the new CDI system the coding has been extended to a 24 digit 2C code The I2C coding permits even more accurate tuning injection quantity and injection period of the indi vidual piezo injectors when new If a piezo injector is replaced the CDI control unit must be supplied with this coding via Star Diagnosis It must be ensured that the correct I2C codes are entered after replacing the injectors If the I2C codes are entered incorrectly or not at all the following problems may arise Smoke formation e Rough or vibrating engine Power loss e Generation of noises P07 03 2242 00 Piezo injector gt CDI Diesel Direct Injection for OM 651 System Description This printout will not be recorded by the update service Status 09 2008 Piezo injector Actuation of piezo injectors Engine OFF Ignition ON The pressure in the low pressure fuel system is built

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