engine cdi

Passenger cars • Engine Common RailDiesel Injection (CDI) Specialist trainingImformation module

Passenger cars • EngineCommon Rail Diesel Injection (CDI)Specialist training

Information module

As at 03/04

This document is provided for training purposes only and is not subject to the normal updates.

Printed in Germany

� 2002 Copyright DaimlerChrysler AG

Issued by: Global Training

This documentation and all its constituent parts are subject to copyright. Any reproduction or re-use requires writtenpermission from DaimlerChrysler AG in advance. This especially applies to any duplication, dissemination, editing,translating, microfilming of this documentation, or storage and/or processing on electronic systems, databases andonline services.

Note:The term "employee" always refers toboth male and female staff.

1511 1120 00 - 2. Edition 03/04 78 Stand 01/04.

Content 05.03.2004

Title Page

Model overview ........................................................................................................................................................................................................................................1

Engine characteristics..............................................................................................................................................................................................................................2

Fuel system..............................................................................................................................................................................................................................................8

Supercharging........................................................................................................................................................................................................................................27

Cooling circuit ........................................................................................................................................................................................................................................35

Preheating system .................................................................................................................................................................................................................................37

Intake port shutoff (EKAS) .....................................................................................................................................................................................................................39

Exhaust gas recirculation (EGR).............................................................................................................................................................................................................41

Exhaust gas guidelines...........................................................................................................................................................................................................................44

Diesel particulate filter (DPF).................................................................................................................................................................................................................45

CDI control unit......................................................................................................................................................................................................................................60

European On-Board Diagnosis (EOBD) on CDI engines .........................................................................................................................................................................63

CAN Data Bus ........................................................................................................................................................................................................................................65

Synchronization .....................................................................................................................................................................................................................................66

Heater booster (HB) ...............................................................................................................................................................................................................................69

Vehicle settings for test purposes .........................................................................................................................................................................................................71

Safety concept diesel engine.................................................................................................................................................................................................................72

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Model overview 1

Model overview 05.03.2004

Sales designation Model designation Enginedesignation

Displacementcm³

Injection system Rated outputkW at rpm

Rated torqueNm at rpm

A 160 CDI 168.006 668.940 1689 CDI 1 55 at 3600 160 at 1500 - 2800

A 170 CDI 168.009 668.942 1689 CDI 1 70 at 4200 180 at 1600 - 3200

C 200 CDI 203.007/207/707 646.962 2148 CDI 3 90 at 4200 270 at 1600 - 2800

C 220 CDI 203.008/208/708 646.963 2148 CDI 3 105 at 4200 340 at 2000

C 270 CDI 203.016/216 612.962 2688 CDI 2 125 at 4200 400 at 1600 - 2400

C 30 AMG 203.018/218/718 612.990 2950 CDI AMG 170 at 3800 540 at 2000 - 2500

CLK 270 CDI 209.316 612.967 2688 CDI 2 125 at 4200 400 at 1800 - 2600

E 200 CDI 211.004 646.951 2148 CDI 3 90 at 4200 270 at 1400 - 2800

E 220 CDI 211.006/206/606 646.961 2148 CDI 3 110 at 4200 340 at 1800 - 2600

E 270 CDI 211.016/216/616 647.961 2688 CDI 3 130 at 4200 400 at 1800 - 2600

E 320 CDI 211.026/226 648.961 3222 CDI 3 150 at 4200 500 at 1800 - 2600

E 400 CDI 211.028 628.961 3996 CDI V1 184 at 4000 560 at 1700 - 2600

S 320 CDI 220.025/125 648.960 3222 CDI 3 150 at 4200 500 at 1800 - 2600

S 400 CDI 220.028/128 628.960 3996 CDI V1 184 at 4000 560 at 1800 - 2600

ML 270 CDI 163.113 612.963 2688 CDI 2 120 at 4200 370 at 1800 - 2400

ML 400 CDI 163.128 628.963 3996 CDI V1 184 at 4000 560 at 1700 - 2600

G 270 CDI 463.322/323 612.965 2688 CDI 2 115 at 3800 400 at 1800 - 2500

G 400 CDI 463.309/332/333 628.962 3996 CDI V1 184 at 4000 560 at 1700 - 2600

Note: This table is not exhaustive.

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Engine characteristics 2

Engine characteristics 05.03.2004

Engine 668

Engine 668 is a 4-cylinder in-line engine, mountedon the front axle carrier across the direction oftravel. The engine is inclined at 59° to thedirection of travel.The engine construction was specially adapted forthe A-Class vehicle concept.

Technical features:� Aluminum crankcase (open-deck design)� Cylinder liner of gray iron� 60° valve arrangement (4 valves)� Crankcase ventilation with spiral oil separator� Fuel preheating with

fuel preheating valve� Non-classified injectors� Wastegate turbocharger� CDI 1 injection system� EU3 certified

In Autumn 2004, the M668 is being replaced inthe new A-Class by its successor engine, theM640.

P01.00-0508-76


Engines 611, 612, 613

Technical features:

� Gray iron crankcase� 4-valve technology� VTG turbocharger� Oil filter integrated with the timing case cover� Oil cooling with oil/water heat exchanger� Classified injectors (611, 612 only)� De-nitrogen oxide catalytic converter� CDI 2 injection system� Intake port shutoff� EU3 certified

As in previous diesel engines with gray ironcrankcases, the cylinders do not have cylinderliners.

The engines in this model series have been for themost part replaced by the new 646, 647 and 648engines.

P01.00-2239-76


Engines 646, 647, 648

GT03_20_0003_C73

Technical features:

� Gray iron crankcase� 4-valve technology� Electric actuator for VTG turbocharger and exhaust gas recirculation valve� Flow controlled high-pressure pump� Classified injectors (Injector quantity adjustment - IMA) from CDI 3 upwards� Electric fuel feed pump in the tank� Oxygen sensor (EU4)� No fuel cooler/preheating� Diesel particulate filter (DPF) as special equipment (EU4)� Electric throttle valve actuator� CDI 3 injection system� EU3 certified (with EU4 diesel particulate filter)

Lanchester balancerAs a special engineering feature, the Lanchester balancer was first introduced in the M646, for vibrationdamping.Its purpose is to compensate the inherent inertia forces in a 4-cylinder in-line engine and thus suppressdisturbing vibrations.

It consists of two counter-rotating shafts, which are fitted with unbalanced weights.The Lanchester balancer is bolted to the bottom of the crankcase in a gray iron housing in the oil pan,and is driven by a gear on the crankshaft.

A drilling in the crankcase provides the oil feed to the balancer.Two spacers ensure the correct gear backlash.When mounting the balancer, gear backlash must be measured again and adjusted if necessary.


Engine 628

Crankcase

The two-part crankcase (bedplate design) makes it possible to close off the crankshaft compartment fromthe oil pan at the bottom. This creates a highly rigid unit, without the need for additional components. Thecrankshaft compartment is divided at the bottom into four separate compartments by the closed end ofthe crankcase, one compartment for each pair of cylinders. This forms an enclosed space beneath thepiston, which varies according to piston position, and which is only connected with the oil pancompartment by means of special oil return ports (A). The four compartments have no pressurecompensation connections with each other.

The small oil return ports and the closed crankshaft compartment cause an increased pressure under thepiston at the piston downward movement, which is released again at the upward movement. Thisproduces smoother engine operation.

P01.40-2038-06

Cylinder and valve assembly

The cylinder spacing is the same as on Engine 611 (97 mm). Consequently, the two aluminum cylinderheads and the valve control elements on the V-engine, with four valves per cylinder, two hollow castcamshafts per cylinder bank, and cup tappets, are of the same design as the 4-cylinder in-line 611engine. In many cases, the same parts can be used. The cylinder head on the right cylinder bank isidentical in construction. The inlet and outlet ports in the left cylinder head are a reverse image of theright.

On the in-line engines, the exhaust camshafts and high-pressure fuel pump are driven by a two-row chain,which has been adapted to the 8-cylinder engine by means of the tensioning elements.


Balance shaft

To be able to install the V-engine at the front end in W220 series vehicles, without having to makechanges to the vehicle body, a V angle of 75 degrees was selected. The same 90### firing interval wasachieved by changing the settings of the crank pins on opposing cylinders by 15### relative to eachother.

The first-order mass moments (vibrations) due to this V-angle are compensated by a balance shaft, whichis located in the V-compartment of the engine and rotates counter to the crankshaft at crankshaft speed.The balance shaft carries a centrifugal oil separator (3) at the front end. This is integrated with the frontcorrectional weight.

P03.00-2014-01

P01.20-2026-76

Crankcase ventilation and pressure regulator valve

A centrifugal oil separator on the balance shaft, driven by the timing chain, separates the gases in thecrankcase from the oil particles.The cleaned gases are passed through the intake air pressure regulator valve.

The pressure regulator valve (3) is mounted on the oil filter housing.The purpose of this valve is to reduce the flow of gas mixture if there is too high a vacuum between thecharge air manifold and the crankcase.At a vacuum of over 50 mbar in the charge air manifold, the connection with the crankcase is closed by adiaphragm, so that no oil vapor / oil is extracted and burned / consumed.

To prevent the pipes (A) from freezing up, they are warmed by the engine coolant lines (B) that passthrough them.


M612.990 (C 30 CDI AMG)

The heart of the C 30 CDI AMG is the advanced turbodiesel engine, which is based on thefamiliar C 270 CDI (M612).The 612 engine has been completely re-engineered in order to achieve high output levels.

Newly developed crank mechanism, oil spray nozzles and oil pumpNew layout of cylinder head boltsAdditional electric in-tank fuel pumpHigh-pressure injection pump and injectors adapted to deliver greater fuel quantitiesUse of a special electrically controlled AMG turbochargerNewly designed charge air ducting, made of sandcast aluminum and high-temperature

silicone hosesCharge air cooler as air/water heat exchangerBelt drive, engine support and engine cover have been adaptedNewly developed hardware and software for engine managementControllable glow system with high-temperature glow plugsElectric heater booster no longer necessarySpecial exhaust system with underfloor catalytic converters no longer necessaryIntake port shutoff no longer necessaryNEDC fuel consumption 7.6 – 7.9 L/100 kmEU3 certified

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Fuel system 8

Fuel system 05.03.2004

CDI 1 The original CDI 1 system fitted to passenger vehicle engines (M611 and 668) is the same one installed inthe M668 (A-Class and VANEO).The difference between this and its CDI 2 successor system is not in the fuel system, however, but in theturbocharger design (see "Supercharging").The electric shutoff valve (Y75) has been discarded.The maximum system pressure is 1350 bar.

M668, shown on Model 168

B4/6 Rail pressure sensorY74 Pressure regulator valveY75 Electric shutoff valve (up to 05/01)Y76 Injector13 Fuel feed pump19 High-pressure pump70 Fuel filter71 Fuel preheating valve80 Fuel tankA Fuel pressure from fuel feed pumpC Fuel returnD Fuel high pressureF Fuel vacuum

P07.16-2057-79


CDI 2 The revised 611 engines (CDI 1, CDI 2) and the new 612 and 613 engines (CDI 2) were fitted withvariable-nozzle turbochargers (see “Supercharging”).To distinguish the designations of these engines from the old engines (despite use of the same injectionsystem), the CDI 2 designation has been added.Here also, the electric shutoff valve (Y75) was discarded as of 04/2001.The maximum system pressure is 1350 bar.

M611, shown on the Model 202

B4/6 Rail pressure sensorY74 Pressure regulator valveY75 Electric shutoff valve (up to 03/01)Y76 Injector13 Fuel feed pump14 Fuel cooler19 High-pressure pump60 Fuel preheating70 Fuel filter80 Fuel tankA Fuel pressure from fuel feed pumpC Fuel returnD Fuel high pressureF Fuel vacuum

P07.16-2194-79


CDI V1

M628, shown on the Model 220

B4/6 Rail pressure sensorM3 Fuel feed pumpY74 Pressure regulator valve

The development of the M628 also brought a range of new components to the fuel system. To indicatethe V-engine layout, the fuel system is called the CDI V1.An electric fuel feed pump (M3) is used here for the first time, to provide the fuel supply and support themechanical fuel pump (13). A failure of this pump causes the engine to switch off when under load.

To reduce the energy absorbed by the high-pressure pump and unnecessary heating of the fuel, thequantity control valve (Y94) ensures that some of the fuel flowing to the high-pressure pump is returneddirectly to the fuel tank.Depending on the engine layout (V-engine), fuel is supplied to both rails by the valve block. The pressureregulator valve and rail pressure sensor are also fixed to this block.The maximum system pressure is 1350 bar.

Y76 InjectorY94 Quantity control valve13 Fuel feed pump14 Fuel cooler19 High-pressure pump19/23 Fuel pressure relief valve21 Rail21/7 Valve block70 Fuel filter71 Fuel preheating valve80 Fuel tank93 Pressure relief valveA Fuel vacuumB Fuel pressure from fuel feed pumpC Fuel pressure from fuel feed pumpD Fuel return to fuel feed pump with fuel pressure

Fuel pressure relief valveE Fuel pressure from quantity control valve

to annular port in the high-pressure pump

F Fuel high pressureG Fuel return

P07.16-2259-79


CDI 3 The CDI 3 engines 646, 647 and 648 are being brought in to replace the CDI 2 engines 611, 612 and613. The CDI 3 system contains components and innovations that are already present in theCDI V-system.For example, the fuel system is equipped with an electric fuel pump only. The quantity control valve (Y94)controls the flow to the high-pressure pump. Depending on the load condition, only the fuel quantity thatis really necessary is fed into the rail.

System components such as the fuel preheater, mechanical fuel feed pump and fuel cooler have beendiscarded. Consequently, to prevent overheating of the fuel, a temperature sensor (B50) has been fittedto the high-pressure pump. In connection with the quantity control valve (Y94), this sensor prevents theflow to the rail and thus overheating of the fuel (tank protection).

The maximum system pressure is 1600 bar.

M646, shown on Model 211

B4/6 Rail pressure sensorB50 Fuel temperature sensorM3 Fuel feed pumpY74 Pressure regulator valveY76 InjectorY94 Quantity control valve19 High-pressure pump21 Rail70 Fuel filter80 Fuel tank80/17 Fuel feed moduleA Fuel to the filterB High pressure lineC Fuel return

P47.00-2060-79


M612.990 in the C 30 CDI AMG The structure, function, and controls of the high-pressure system in the C 30 CDI AMG engine are madeup of a combination of the CDI 2 and CDI V1 systems. However, the system has been given thedesignation CDI 2.The new features of the 612 engine are above all the electric fuel feed pump and the quantity controlvalve (Y94). The maximum injection pressure is 1350 bar.

13 Mechanical fuel feed pump14 Fuel cooler19 Fuel high-pressure pump19/23 Fuel pressure relief valve21 Rail70 Fuel filter71 Fuel preheating valve80 Fuel tankB4/6 Rail pressure sensorM3 Electric fuel feed pumpY74 Pressure regulator valveY76 InjectorY94 Quantity control valve

P07.16-2441-09


Fuel low pressure

Fuel tank with in-tank pump

P47.10-2151-00

An electric in-tank pump is installed in the new model series with CDI 3 engines, with the M628 in theW211 and in the C 30 CDI AMG.The fuel tanks on Model 211 with Engine 628 and the C 30 CDI AMG have the same function. The electricin-tank pump (about 0.5 bar) only provides support to the mechanical fuel pump. The delivery pilotpressure is controlled by a valve in the tank.On the CDI 3 system, the electric fuel pump raises the overall low pressure (about 4.5 bar). This pressureis controlled by a valve in the high-pressure pump.

The return flow from the engine actuates the suction jet pumps in the fuel tank. One of them supplies fuelfrom the left half of the tank to the swirl pot. The other pump, in the right half of the tank, maintains thefuel level in the swirl pot, so that there is always sufficient fuel available to the electric fuel pump.

The swirl pot is fitted with a valve, so that laborious manual bleeding operations are not necessary if thetank is allowed to run dry.

C 30 CDI AMG fuel tank


Fuel preheating Function

GT07_16_0033_C72

Example of a fuel heat exchanger

Fuel has to be preheated in order to prevent engine running faults due to diesel/paraffin characteristicsat low temperatures.This improves the fluidity of the fuel and normally enables fault-free operation with winter diesel down to -25°C outside temperature.

Operation

There are three basic different types of preheating system:� Fuel preheater

The cold fuel is warmed by coolant. When the fuel is warm, a thermostat stops the flow to the heatexchanger.

� Fuel preheating valveThe warmed fuel from the fuel return is mixed with the cold fuel. A bimetal valve controls the mixtureaccording to the temperature.

� Heating by controlled return flow (CDI 3)For up to 30 seconds after engine starting with fuel temperatures below 20°C, there is no throttling ofthe feed to the high-pressure pump. All of the fuel is placed under high pressure, and its temperaturetherefore rises.The heated fuel flows through the pressure regulator valve (Y74) to the fuel tank.

Legend:

A Fuel return from rail

B Fuel return to fuel tank

71/1

71/271/371/6

71/571/471/7

ab

c c

ab

A B71/8

c Connection to fuel filter

P07.16-0316-00


Fuel cooling

Various fuel cooling systems are used in vehicles to cool the fuel after it has been heated in the rail:

� Fuel cooling by the metal tank only (M668)� Fuel cooling by a fuel/water heat exchanger (C-Class, M-Class and all vehicles with M628)� Fuel cooling by an underfloor fuel/air heat exchanger (Model 210)� Electronic fuel cooling (heating prevention) by a controlled high-pressure pump

(CDI 3 system)

P07.16-2111-01

Example: W210


Mechanical fuel feed pump Purpose

In CDI 1 and CDI 2 engines, the mechanical fuel feed pump (13) ensures a sufficient supply of fuel to thehigh-pressure pump (19).In Engine 628, it is assisted by an additional electric fuel feed pump (M3). In CDI 3 engines, it has beencompletely replaced by an electric fuel feed pump.

Mechanical fuel feed pump operation

Since the high-pressure pump cannot draw in fuel by itself, the fuel feed pump (13) draws the fuel fromthe tank through the fuel filter, and feeds it through the electromagnetic shutoff valve (Y75) to the high-pressure pump.

P07.16-0233-71

a Suction side of main filterb Pressure side to elect. shutoff valve (Y75)13/11 Plug13/12 Pressure relief valve opens at aro 3.5 bar13/13 Valve springA Fuel pressure from fuel feed pump

to shutoff valve (Y75)F Fuel vacuum

Fuel pressure:� At cranking speed about 0.4 -1.5 bar� At idle speed about 2.0 -2.5 bar� Integrated pressure relief valve limits the pressure to 3.5 ± 0.5 bar.


Fuel temperature sensor Function

The fuel temperature sensor (B50) is only installed in CDI 3 engines. It performs the "fuel preheating“ and"tank protection" functions.

“Fuel preheating” function

The NTC resistor in the fuel temperature sensor varies its electrical resistance according to fueltemperature. “NTC” stands for Negative Temperature Coefficient, i.e. the resistance decreases astemperature increases.When the fuel is cold (< 20°C), the pressure regulator valve controls rail pressure.This causes the fuel to heat up.

GT07_16_0006_C81 “Tank protection” function

The rail pressure is lowered to protect the fuel tank from overheating (> 90°C). The fuel temperaturesensor (B50) measures the temperature of the fuel feed from the tank at the high-pressure pump flange.If the fuel is too warm, the CDI control unit (N3/9) actuates the quantity control valve (Y94) and closes itto reduce the rail pressure. The fuel then no longer flows to the high-pressure pump, but directly backinto the tank.

B4/6 Rail pressure sensorB50 Fuel temperature sensorN3/9 CDI control unitY94 Quantity control valve

P07.16-2396-76


Fuel high pressure

High-pressure pump

The high-pressure pump is a radial piston pump with three pump elements offset at 120°. These aremoved by an eccentric on the pump drive shaft.

The pump is lubricated with diesel fuel, and this makes the pump vulnerable if fed with air, gasoline, orwater. This causes chips to form on the pump elements, or can even cause the pump to block or seize up.

� Procedure for incorrect fueling: SI47.10-P-0004A

CDI 3 high-pressure pumpIn the CDI 3 system, the fuel temperature is detected in the feed to the pump elements, and the feed iscontrolled by the quantity control valve.The fuel low pressure (about 4.5 bar) is controlled by a pressure relief valve at the pump.

CDI V1 and CDI 2 high-pressure pump in the M612.990 (C 30 CDI AMG)In these systems, the mechanical fuel feed pump is mounted at the high-pressure pump. There is also aquantity control valve located in the base plate. However, this is not controlled by the pressure in the rail(as in the CDI 3), but is actuated according to a performance map and controls the feed to the high-pressure pump.


Rail pressure sensor (B4/6) Location

The rail pressure sensor is fixed to the side of the rail.

P07.04-2125-01

Function

Its purpose is to measure the current rail pressure and send this to the CDI control unit (N3/9). Thepressure regulator valve (Y74) or the quantity control valve (Y94) is then actuated by the CDI control unit(N3/9) through a control loop, until the desired rail pressure is reached.

Design

The system pressure affects the position of a diaphragm. This causes a change in its electrical resistance,which is then evaluated.

� Check for system leaks when mounting on the rail.


Quantity control valve The quantity control valve (Y94) is fitted to the high-pressure pump in all CDI 3 engines, and in the M628and M612.990. In the CDI 3 system, a ‘requirement-driven’ high-pressure pump is used.

GT07_16_0057_C71

a Controlled fuel quantity to thehigh-pressure pump elements

b Fuel feed from the fuel pumpc Electrical connectionY94 Quantity control valve

FunctionAlong with the pressure regulator valve (Y74), the quantity control value (Y94) controls the rail pressure.Fuel quantity to the high-pressure pump elements is regulated according to the PWM signal from the CDIcontrol unit (N3/9). In the CDI 3, this prevents undesired high fuel temperatures in the fuel return line, ascompared with unregulated high-pressure pumps. By throttling the fuel quantity, the power absorbed bythe high-pressure pump is also reduced.

CDI 3 operationThe fuel from the feed pump (M3) passes into the high pressure pump flange, and from there through thefuel temperature sensor (B50) to the quantity control valve (Y94).The quantity control valve (Y94) sets the fuel quantity according to the signal from the CDI control unit(N3/9).A controlled fuel quantity is thus fed to the three pump elements. This varies the filling quantity in thepump cylinder and therefore the fuel quantity fed to the rail. In the CDI 3 system, the rail pressure ismainly controlled through the quantity control valve.Any excess fuel delivered is passed back through the high-pressure pump return line to the fuel tank.

Quantity control is applied:� About 30 s after engine start� Fuel temperature > 20°C� Not when coasting

CDI V1 and M612.990 operationThe fuel regulated by the quantity control valve is fed to the intake of the mechanical fuel pump.The quantity control valve is actuated accordingly by the performance map, and only roughly regulates thefeed to the high-pressure pump. The rail pressure is controlled by the pressure regulator valve only.

Y94

b

b a

c


Pressure regulator valve (Y74)

P07.16-2337-01 P07.16-0275-01 P07.16-0250-01

16/1 High-pressure feed16/2 Return flow

16/3 CoilY74 Pressure regulator valve

a Magnetic forceb Spring forcec Ball seat

FunctionTo regulate and stabilize rail pressure according to the control signals from the control unit.

OperationThe high pressure in the rail is applied through the high-pressure feed (16/1) to the valve seat (c) of the pressure regulator valve (Y74).Rail pressure is set by the pressure regulator valve (Y74) building up a magnetic force (a) that corresponds to the specified pressure indicated by the PWMsignal. This magnetic force causes a corresponding outlet cross-section at the ball seat (c). The rail pressure varies according to the quantity of fuel flowing fromthe outlet. The rail pressure sensor sends the current rail pressure value to the CDI control unit (N3/9). Excess fuel flow back through the fuel return line to thetank. In the de-energized state, the pressure regulator valve (Y74) is closed, since the spring force pushes the ball into the ball seat (c) (only up to 90 bar).When starting, it is held closed by spring force (b) and magnetic force (a).In operation, the fluid pressure (16/1) acts against the magnetic force of the coil (a) and the spring force (b).

In CDI 3 engines, the pressure regulator valve controls the rail pressure for up to 30 s after engine start, at fuel temperatures below 20°C, and when coasting.


Fuel injector Here we examine the injector as implemented on the current CDI 3 system.

One important feature of the injector is the newly developed seven-hole injection nozzle, which replacesthe previous six-hole nozzle used in the CDI 1, CDI 2 and CDI V1 systems.

GT07_16_0007_C03

This allows the nozzle hole diameter to be reduced by about 20 percent.The result is an even finer atomization and fuel distribution, and therefore even better mixture formation.It also reduces the level of particulates in the exhaust flow.However, the heightened throttling effect produced by the smaller nozzle holes causes a lengthening ofthe injection period, which would be a particular disadvantage as higher power output is developed. Forthis reason, the injection pressure has been raised to 1600 from the previous 1350.

Another feature of all CDI injectors is two-phase fuel injection (flexible combustion process), whichcompensates for the necessarily higher noise levels of the direct fuel injection system relative to theprechamber engine.This system has been further improved in the 646, 647 and 648 engines through the use of the doublepre-injection system (from 60°C). The powerful magnetic armature in the new injectors considerablyreduces the time interval between the pre-injection and main injection, so that little pilot quantities arenow delivered to the combustion chambers twice in succession - in less than a millisecond - thusensuring even better preheating of the combustion chamber with fewer pressure peaks.

Depending on engine speed and load, the double pre-injection changes over to single pilot injection,before being switched off completely at full load.

The injection quantity at the injectors is determined by:� actuation of the magnetic coil (actuation period)� opening and closing speed of the nozzle needle� needle lift� nozzle geometry� rail pressure


Correction functions Smooth running controlThe smooth running control reduces irregular engine running when in neutral. The CDI control unit CDI(N3/9) receives an engine speed signal from the crankshaft position sensor (L5) and detects anyirregularities in the engine running characteristics.These irregularities in the engine running characteristics are corrected by cylinder-specific adjustment ofthe injection quantities. The idle speed is therefore kept constant.Smooth running control is active for engine speeds up to about 1200 rpm.

GT07_16_0035_C71

CDI 2 injector classificationInjector classification was introduced in July 2000 for 611 and 612 engines with CDI 2.The classification of injectors into 3 classes indicates the fuel quantity characteristic of the injectors. Thismakes it possible to tune the engine software more finely to the tolerance ranges of the injectors.

At production, injectors are selected according to their fuel quantity characteristics.

Injector identification and procedure� Classified injectors are identified by their part number and the identifier on the magnetic head (circle

containing a number from 1 to 3). The number indicates the classification. CDI 2 injectors that do nothave a circled number are of classification 2.

� If an injector is being replaced on a vehicle with injector classification, the classification number mustbe assigned to the corresponding cylinder using the DAS system, when adapting the control unit underthe “Classification” menu item.

If classification is not carried out, faults may occur, such as smoke formation, rough engine running orvibrations.


Two types of injectors can be found in the CDI 3 system:When the CDI 3 was first introduced, the injectors were not classified. These injectors are now identifiedby a � mark on the injector head.There are also no classifications in the control unit.

GT07_16_0032_C71

Injector quantity adjustment (IMA)From the middle of 2003, a 6-digit code was introduced on the injector head for the CDI 3 system update.This conceals an even more finely tuned classification, which is called injector quantity adjustment (IMA -InjektorMengenAusgleich).The classification is entered in the DAS system in the usual way.

Zero quantity calibrationWhen coasting, the control unit can use the zero quantity calibration to measure the effective dead timeof injectors during preinjection. The injection quantity is slowly raised until an increase in rpm can bemeasured at the crankshaft. The measured length of the actuation period is used by the CDI control unit(N3/9) as a correction value for the start of injection.

In connection with the O2 sensor (see next page), injector aging can also be taken into account by theCDI control unit when controlling the quantity of fuel injected.

P07.16-2514-81


O2 sensor in front of the TWC

Detects residual oxygen content in the exhaust gas and sends the corresponding signal to the CDIcontrol unit.

On EU 4 vehicles, injector aging (long-term drift) is detected using the O2 sensor.In this way, the CDI control unit can adjust the mixture formation through the exhaust gas recirculationrate (in the same way as the self-adjustment in gasoline engines).

The broadband oxygen sensor can measure accurately not only at � = 1, but also in the leaner andricher ranges.In connection with the control electronics integrated in the CDI control unit, it sends a clear signal overa wide Lambda range (0.7 < � < 4.0).

The O2 sensor (G3/2) is located in front of the catalytic converter.P07.04-2117-01

� The oxygen sensor has no effect on the DPF!

P07.04-2196-01


CDI 3 high-pressure control circuit Components involved and signal flows.

Operation

The rail pressure sensor (B4/6) measures thecurrent fuel pressure in the rail and sends thecorresponding voltage signal to the engine controlunit (N3/9). From the input signal, the enginecontrol unit identifies the current engineoperating condition and driver intention. To adaptthe rail pressure, a PWM signal determined by aperformance map is sent to the pressureregulator valve and quantity control valve, untilthe specified pressure is reached in the rail.The injection quantity depends on the railpressure and actuation period of the injectors.

21 RailB11/4 Coolant temperature sensorB37 Accelerator pedal sensorB4/6 Rail pressure sensorL5 Crankshaft position sensorN10/1 SAM control unit with fuse and

driver relay moduleN3/9 CDI control unitY74 Pressure regulator valveY94 Quantity control valve

P07.16-2374-76

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Supercharging 27

Supercharging 05.03.2004

Overview The purpose of the supercharging (turbocharger) system is to ensure the appropriate boost pressure foreach operating condition of the engine, and so raise the engine output and torque.

Various types of supercharging system are installed in the current diesel engines.

CDI 1 (M668) CDI 2 (M611, 612, 613) CDI V1 (M628) CDI 3 (M646, 647, 648)

Turbocharger type Wastegate Variable Turbine Geometry (VTG) Two VTG turbochargers Variable Turbine Geometry (VTG)

Actuation Pressure transducer andvacuum control unit

(continuously variable)

Pressure transducer and vacuumcontrol unit (continuously

variable)

Electric adjuster (continuouslyvariable)

Electric adjuster (continuouslyvariable)

P09.40-0202-76 P09.40-2014-76 P09.40-2045-76

Wastegate turbocharger(CDI 1)

VTG turbochargerwith pneumatic actuation (CDI 2)

VTG turbochargerwith electric actuation (CDI V1, CDI AMG, CDI 3)


Wastegate turbocharger

Operation

Boost pressure is controlled by opening and closing the bypass (E)(wastegate).

The engine exhaust gases are passed through the exhaust manifold into theturbine housing (f) on the turbine wheel (g). The exhaust flow energy (C) setsthe turbine wheel turning.

This causes the compressor turbine wheel (d), which is connected to theturbine wheel by the turbine shaft, to turn at the same speed. Depending onaltitude, the maximum speed can be up to 180000 rpm.The fresh air drawn in by the compressor turbine wheel (A) is compressed (B)and then passed to the engine.

When the bypass is open, there is no pre-compression, and the engineoperates like a naturally aspirated engine. When the bypass is closed, theexhaust gases flow onto the turbine wheel (g). The bypass flap (a) is actuatedby the vacuum control unit of the boost pressure control valve (110/10).

110/10

B

A D

h

d c J f g

E

a

CH

n

P09.40-0202-76

a Bypass flapc Compressor housingd Compressor turbine wheelf Turbine housingg Turbine wheelh Intermediate housingn Turbine shaft

A Compressor inlet (fresh air)B Compressor outlet (pre-compressed air)C Exhaust gas to the turbine wheelD Exhaust gas outletE BypassH Oil inletJ Oil outlet

110/10 Boost pressure control valve / vacuum control unit


Turbocharger with Variable Turbine Geometry(VTG)

The turbochargers in the CDI 2, CDI V1 and CDI 3 systems differ only in the way they are actuated (byvacuum control, electrically).

OperationThe engine exhaust gases are passed through the exhaust manifold into the turbine housing (a) on theturbine wheel. The exhaust flow energy (C) sets the turbine wheel (b) turning. This causes the compressorturbine wheel, which is connected to the turbine wheel by the turbine shaft, to turn at the same speed.The fresh air drawn in by the compressor turbine wheel (A) is compressed (B) and then passed to theengine.The boost pressure is controlled by adjusting the position of the guide vanes (h).

1. At low rpm, the flow cross-section (i1) is reduced by closing the guide vanes (h). This increases theflow velocity of the exhaust gas at the turbine wheel. The rotational speed of the turbochargertherefore rises and the boost pressure increases.

2. At high rpm, the guide vanes (h) are opened progressively, thus increasing the flow cross-section (i2).This reduces the turbocharger rotational speed and the boost pressure falls.

� Variable nozzle (VTG) turbochargers are very sensitive. They should in no circumstances besubjected to strong mechanical loads or knocks, as otherwise the guide vanes may seize up orthe electric actuator may be damaged.Also, the turbocharger unit and actuator must never be detached from each other, and the lengthof the control rod must not be adjusted.Faulty turbochargers often give rise to implausible values in the boost pressure sensor.


P09.40-2014-76 P09.40-2027-76 P09.40-2045-76

Pneumatic actuation (CDI 2) Electrical actuation (CDI V1) Electrical actuation (CDI 3)

A Compressor inlet (fresh air)B Compressor outlet (pre-compressed air)C Exhaust gas to the turbine wheelD Exhaust gas outleta Turbine housingb Turbine wheelc Compressor housingd Control linkagee Pilot stud on control linkagef Adjusting ring

g Pilot stud on guide vaneh Guide vanei1 Flow cross-section with guide vanes ‘closed’i2 Flow cross-section with guide vanes ‘open’1 Guide vanes ‘closed’2 Guide vanes ‘open’Y100 Left boost pressure regulator, electric (M628)Y100/1 Boost pressure regulator, electric (M646)Y100/10 Boost pressure regulator, pneumatic (M611)


Boost pressure control

P07.10-0317-82

The boost pressure is controlled by the CDI control unit according to the stored boost pressureperformance map. The boost pressure regulator(s) (the M628 has 2 turbochargers) are actuated by aPWM signal from the control unit and determine the position of the guide vanes of the VTG turbocharger.The required boost pressure is thus provided for each engine operating point.

In the M628, both turbochargers must be synchronized, in order to avoid uneven pressure buildup. Theyare adjusted by signals from both hot film MAF sensors in such a way that the same air mass flow rate ispresent in both the left and right intake systems.

If the turbocharger is actuated by a vacuum control unit, a PWM signal is sent to the pressure transducer(Y31/5), which applies the corresponding vacuum at the vacuum control unit and continuously adjuststhe VTG turbocharger.

In the CDI 3 and CDI V1 engines and in the C 30 CDI AMG, to avoid overrevving of the turbocharger (forexample if the air cleaner is clogged), the air pressure is also detected after the air cleaner. Depending onload, this air pressure must not go below a certain pressure value, and must always be in the same ratioto the boost pressure.

The input values for the charge air control are as follows:� Charge air pressure / temperature� Atmospheric pressure� Coolant temperature� Oil temperature� Engine load / rpm� Drive position� Air mass (M628, 612 990)� Air pressure after air cleaner (CDI 3, CDI V1, C 30 CDI AMG)

Y31/5 Boost pressure control pressure transducer1 Ventilation (ATM)2 Vacuum from vacuum pump (VAC)3 Connection to boost pressure control vacuum control unit (OUT)


Charge air ducting

CDI 1 (M668) CDI 2 (M612)

P09.40-2001-76 P09.00-2009-76

1 Intake module107 Exhaust manifold110 Turbocharger110/1 Charge air distribution tube110/2 Charge air cooler110/6 Charge air pipe

A Compressor inlet (fresh air)B Compressor outlet (pre-compressed air)C Exhaust gas to the turbine wheelD Exhaust gas outletATM Ventilation to major assemblies compartmentOUT Outlet from pressure transducerVAC Vacuum from vacuum pump


CDI V1 (M628) CDI 3 (M647)

P09.40-2028-76 P09.40-2047-76

107 Exhaust manifold110 Turbocharger110a Turbocharger110/1 Charge air distribution tube110/2 Charge air cooler110/6 Charge air pipeB17/8 Charge air temperature sensor

B28 Charge air pressure sensorY100 Left boost pressure regulatorY100/1 Boost pressure regulatorA Compressor inlet (fresh air)B Compressor outlet (pre-compressed air)C Exhaust gas to the turbine wheelD Exhaust gas outlet


Charge air cooling A mass of warm air has a larger volume than the same mass of cold air.

To achieve the optimal volumetric efficiency of the cylinders, the intake air, which has been heated bycompression, must be cooled down again. The CDI control unit receives data from the charge airtemperature sensor (B17/8).

There are two types of charge air cooling system:� Air/water heat exchanger (for example, on M646 in Model 203)� Water heat exchanger (for example, on M628 in Model 220)

110/2 Charge air cooler in the M646 in Model 203 (air/water heat exchanger)

P09.41-2027-01

Water heat exchangers have the advantage of a high degree of efficiency. However, they are expensiveand costly to produce (they need a separate cooling circuit with low temperature cooler and circulationpump).

They are presently installed in:� M628 (not in Model 163 since an air heat exchanger is used)� M612.990 (C 30 CDI AMG, but different design)

110/2 M628 charge air cooler (water heat exchanger)a, b Coolant connectionsc Expansion reservoir connection

P09.41-2025-11

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Cooling circuit 35

Cooling circuit 05.03.2004

M628

The distinguishing feature of the cooling circuit on Engine 628 is its complexity compared with other diesel engines. One particular feature is the separatecooling circuit for the charge air cooling and the fuel cooling.FunctionThe fuel cooler (14) is part of the coolant circuit of the charge aircooler (110/2).The circulation pump (M44) in the charge air cooling system iscontrolled by control unit CDI (N3/9), and delivers the coolantcooled by the low temperature radiator (110/11) to the fuel cooler(14) and charge air cooler (110/2). The fuel (a) from the fuel-preheating valve flows through the fuel cooler (14) and its heat istransferred to the coolant.The low temperature circuit is filled from an expansion reservoir(130) shared with the engine cooling circuit.14 Fuel cooler110/2 Charge air cooler110/11 Low temperature radiator130 Coolant expansion reservoirM44 Charge air cooling circulation pumpa Fuel from fuel preheating valveb Fuel to fuel tankc Vent lineA Coolant from low temperature radiator through

circulation pump to charge air and fuel coolerB Coolant to low temperature radiatorC Pipe to expansion reservoir

P07.16-2217-06

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Cooling circuit 36

M612.990 (C 30 CDI AMG)

Charge air coolingThe low temperature circuit is a self-contained coolant circuit, which is filled from an expansion reservoirshared with the engine cooling circuit.The previous air-cooling system has been replaced by an air/water cooling system that applies thecounter flow principle.

The low temperature coolers are placed one behind the other in the coolant circuit and the coolant flowsthrough each in turn.The circulation pump is continuously adjusted by a PWM signal, according to charge air temperature,engine temperature, accelerator pedal position, and coasting conditions. The pump has integratedelectronics for auto diagnostic tests. For example, if the pump becomes seized, it can be freedautomatically (by changing the direction of rotation).

Compared with simple air cooling systems, controlled charge air cooling ensures a reduced pressure dropon the charging side and shorter response times. Individual control is therefore possible at high outsidetemperatures, and the air is not cooled unnecessarily at low temperatures.

The input signals for the charge air cooling are as follows:� Intake air temperature� Charge air temperature� Engine load

1 Coolant expansion reservoir2 Low temperature cooler 13 Low temperature cooler 24 AC condenser5 Air conditioning system desiccant6 Charge air cooler circulation pump7 Charge air pressure and temperature sensor8 Measuring point for antifreeze tests9 Air/water heat exchanger

Service tip:To ensure the same level of antifreeze protection in both coolant circuits, use only premixed coolant (seebadge).A measuring point (threaded plug M10x1) is fixed to the top of the charge air cooler, for antifreeze testson the charge air coolant circuit.

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Preheating system 37

Preheating system 05.03.2004

P07.16-2389-76

Standard preheating system

The purpose of the preheating system is to heat the combustion chamber tobring it up the required ignition temperature for the air/fuel mixture.

The preheating period of the combustion chamber is divided into:

� PreglowIn key position 2, the glow output stage (N14/2) and preglow indicatorlamp (A1e16) are actuated by the CDI control unit (N3/9).The CDI control unit (N3/9) calculates the preheating time according tothe temperature of the coolant. The glow output stage (N14/2) transmitsthe current to the pencil-type glow plugs (R9).The preglow indicator lamp (A1e16) goes off when the requiredpreheating time has elapsed.

� After-glowWhen the engine is started, the CDI control unit (N3/9) determines theafter-glow period according to the temperature of the coolant.During this time, the glow output stage (N14/2) continues to heat theglow plugs (R9). This improves the engine running after a cold start andthe warm-up characteristics, prevents blue smoke following a cold startand stabilizes the cold-start engine rpm.If there is signal fault in the coolant temperature sensor (B11/4), thesignal from the oil sensor (B40) is used as a substitute.

A1e16 Preglow indicator lampB11/4 Coolant temperature sensorN3/9 CDI control unitN14/2 Glow output stageN73 Control unit for electronic ignition start switchR9 Pencil-type glow plugs

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Preheating system 38

Quick start preheating system in the C 30 CDIAMG

Glow output stageThe preheating system in the C 30 CDI AMG is different from standard preheating systems.An electronically controlled preheating system with high-temperature glow plugs is used(the “Instant Start System” – ISS).The micro-controller in the control unit controls the glow plug by time and voltage, so that the heating-uptime is extremely short and there is a controlled after-glow.This ensures quick key starting even at temperatures down to -25°C, stable idle speed, smooth increasein load and engine speed, and low emissions.

The glow output stage still actuates the glow plugs at a minimum battery voltage of 8 Volts. Each glowplug is actuated and monitored individually and sequentially. This reduces the load on the on-boardelectrical system.

1 Glow output stage

Glow plugsISS glow plugs are designed for a voltage of 5 Volt and can be identified by a red ring at the plug contact(12 V glow plugs have a blue ring). They also have different glow pin geometry.At starting, a brief over-voltage (11 V) is applied to the glow pin. This allows the preglow time to bereduced to 3 s maximum (quick start).

The 5 V voltage level is reached by pulsing the on-board supply voltage (in PWM signals). In this way, aconstant end temperature of 850 to 1000°C is reached and maintained.

A 6 Volt glow plug

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Intake port shutoff (EKAS) 39

Intake port shutoff (EKAS) 05.03.2004

Different versions of the intake port shutoff are installed in CDI engines. In allengines, the purpose and main function is the same. In the 668 and 648engines, and in the M612.990, there is no intake port shutoff.

In the air intake manifold for each cylinder is a swirl port and a filling port. Thefilling ports can be closed by flaps. These are connected to each other by alinkage and adjusted by an electric motor (CDI 2, CDI 3) or a vacuum element(CDI 1, CDI V1).

They are held in the open position by spring force.In the lower rpm and load range, all filling ports (110/19) are closed by theflaps (110/20). All of the air mass flows through the intake swirl ports.

The resulting high turbulence produces a more effective blending of the fuelwith air, and therefore more efficient combustion. This reduces the amount ofsoot particles in the exhaust gas.

GT09_20_0001_C80

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Intake port shutoff (EKAS) 40

As engine speed and load increases, the filling ports in the CDI 2 and CDI 3are open continuously, so that there is the best possible ratio of turbulence toair mass at each operating point, and the optimum exhaust characteristicsand engine power output are achieved. The flaps in the filling ports arepositioned according to the performance map stored in the CDI control unit(N3/9).

� We have learned from experience that the intake port shutoff linkagecan sometimes become detached. The flaps then move aroundunchecked, since the return spring is located on the shaft of theactuator motor.

P07.16-2085-05

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Exhaust gas recirculation (EGR) 41

Exhaust gas recirculation (EGR) 05.03.2004

Function

The purpose of exhaust gas recirculation is to reduce the proportion ofNOx emissions in the exhaust gas. This is done by lowering thecombustion temperature, by feeding the low-oxygen exhaust gases backinto the combustion chamber.

Operation

The exhaust gas recirculation positioner (left: Y27/9) is actuated byPWM signals from the CDI control unit (N3/9).The CDI control unit (N3/9) sets the quantity of recirculated exhaust gasfor the current operating condition, according to the air mass indicatedby the hot film MAF sensor.

The exhaust gas is recirculated according to the performance map in theCDI control unit (N3/9), as soon as the following conditions are present:

P14.20-2058-76

� Battery voltage 11-14 V� Shortly after engine is started� Engine speed > 500 rpm� after idle speed is reached� Partial load

Shown on engine 647101/6 Exhaust gas recirculation cooler107 Exhaust manifold110 Turbocharger110/1 Charge air distribution tube110/2 Charge air cooler

110/6 Charge air pipe110/22 Exhaust gas recirculation port in cylinder headB28/8 Charge air pressure sensorY27/9 Exhaust gas recirculation positioner, leftY100/1 Right boost pressure regulator


Control loop

If the required conditions are present, the exhaust gas recirculation valve is adjusted according to aperformance map.

Actuation

Air mass data

Electr.feedback

N3/9

B2/5Y27/9

The intake air masschanges


P14.20-2029-11

The quantity of exhaust gas recirculated is calculated from the difference between the effective airrequirement and the current quantity of fresh intake air.

Possible sources of error:� Fault exhaust gas recirculation valve (jammed open/closed)� Exhaust gas recirculation port clogged (carbonized)� Hot film MAF sensor faulty (for example, deviates from performance map)

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Exhaust gas guidelines 44

Exhaust gas guidelines 05.03.2004

General Although there have been vehicle emission restrictions since the middle of the 1970s, vehicleemissions have only been falling slowly, partly due to the increasing number of car registrations.This means that exhaust emission standards are becoming stricter and stricter.

As an example, the table below shows the European exhaust emission standards for newdiesel-powered vehicles (g/km).

EU Guidelines

ComponentEuro1

from 1992/93Euro2

from 1996/97Euro3

from 2000/01Euro4

from 2005

CO 2.72 1.0 0.64 0.50

CH + NOx 0.97 0.7 0.56 0.30

Nox - - 0.50 0.25

Particulates 0.14 0.08 0.05 0.025

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Diesel particulate filter (DPF) 45

Diesel particulate filter (DPF) 05.03.2004

From October 2003, in the left-hand drive vehicles shown, 4-cylinder dieselengines (OM646) are now available with optional diesel particulate filter(DPF), Code 474, in combination with the EURO 4 Standard engine version.The 6-cylinder (OM648) engine is available from January 2004.

The Mercedes-Benz diesel particulate filter (DPF), also referred to in the pressas a “soot filter”, allows the almost complete suppression of the particulateemissions produced by the diesel fuel combustion process. TheMercedes-Benz DPF works without any further additives and, in combinationwith measures adaptations inside the engine, meets the exacting EURO 4Standard. Depending on the particular operational profile of the vehicle, theDPF can be used over long mileages with no additional maintenance.

GT14_40_0008_C81

Catalytic converter Diesel particulate filter

C-Klasse Limousinen C 200 CDIC 220 CDI

BM 203.007BM 203.008

Sportcoupé C 200 CDIC 220 CDI

BM 203.707BM 203.708

E-Klasse Limousinen E 200 CDIE 220 CDIE 320 CDI

BM 211.004BM 211.006BM 211.026

S-Klasse Limousine S 320 CDI BM 220.025


Components of the emission control system

1 Catalytic converter (120/1)2 Seal3 Diesel particulate filter (114)B19/7 TWC temperature sensorB19/8 Temperature sensor after TWCB28/8 Differential pressure sensor of diesel particulate filterG3/2 Oxygen sensor in front of TWC

(does not affect operation of the diesel particulate filter)

Components in engine compartment

B60 Exhaust back pressure sensorM16/5 Throttle valve actuator

P07.04-2200-02


Diesel particulate filter operation

The diesel particulate filter (114) consists of aceramic honeycomb filter body, which is made ofsilicon carbide coated with the rare metalplatinum. The ports in the diesel particulate filterare opened alternated at the front and rear, andseparated by the porous filter walls (C) in thehoneycomb body.

The unfiltered exhaust gas (A) flows into the openports at the front of the diesel particulate filter(114), and filters through the porous walls of thehoneycomb filter body (silicon carbide) to theopen ports at the rear.The filtered exhaust gas (B) then passes throughthe exhaust system. In this way, the dieselparticulates are physically retained in the body ofthe diesel particulate filter, where they are burnedduring the regeneration (self-cleaning) phase.

Fouling of the diesel particulate filter is detectedby the CDI control unit by means of thedifferential pressure sensor (TWC) (B28/8).

114 Diesel particulate filter (DPF)A Unfiltered exhaust gasB Filtered exhaust gasC Filter walls

P14.40-2008-06


An oxidation catalytic converter is mounted upstream of the diesel particulate filter, to absorbhydrocarbon (HC) and carbon monoxide (CO).

The diesel particulate filter (114) is screwed together with the oxidation catalytic as a single unit, which islocated on the right of the engine behind the turbocharger.

P14.40-2004-01


Input/Output signals

1 Exhaust gas pressure line before DPF2 Exhaust gas pressure line after DPF114 Diesel particulate filter (DPF)120/1 Oxidation catalytic converterB19/7 TWC temperature sensorB19/8 Temperature sensor after TWCB28/8 Differential pressure sensor of diesel

particulate filterB60 Exhaust back pressure sensorCAN Data bus

(Controller Area Network)G3/2 Oxygen sensor before TWCM16/5 Throttle valve actuatorN3/9 CDI control unitY27/9 Exhaust gas recirculation positionerY76 Fuel injectorsY100/1 Right boost pressure regulator

P14.40-2005-06

Y27/9


Differential pressure sensor

The differential pressure sensor (B28/8) is locatedat the right rear of the engine compartment,behind the heat shield. Through the exhaust gaspressure lines, it detects the difference in gaspressure before and after the diesel particulatefilter. In this way, it can detect soot or ash foulingin the DPF.

If the DPF is full, there is a relatively high pressurein front of the diesel particulate filter, and apressure slightly above atmospheric pressure afterthe DPF.

The exhaust gas pressure before the DPF acts onthe active side of the silicon diaphragm in thedifferential pressure sensor (TWC).The exhaust gas pressure after the DPF is passedto the rear side of the silicon diaphragm.

The deflection of the diaphragm due to thedifferent pressures is measured, and the pressuredifferential deduced.

P07.04-2195-01 P07.04-2198-01


Temperature sensors before/after TWC

The temperature sensor before the TWC (B19/7)is located in the oxidation catalytic converter,above the threaded connection.

The temperature sensor after the TWC (B19/8) islocated in front of diesel particulate filter, underthe threaded connection.

Since the maximum permissible temperature inthe TWC should be 750°C, a sensor is mounted infront of the TWC to monitor the temperature.The temperature in the diesel particulate filter(DPF) should not go above 700°C. A temperaturesensor is therefore mounted behind the TWC (or infront of the diesel particulate filter). Thesetemperatures are reached only during theregeneration phase.

P07.04-2191-01 P07.04-2192-01


Exhaust back pressure sensor (B60)

This pressure sensor measures the gas backpressure in the exhaust gas recirculation channel,in order to adjust the boost pressure according tothe load on the diesel particulate filter. If theexhaust gas back pressure rises, the guide vanesin the turbocharger are adjusted to keep the boostpressure constant.

By means of the exhaust gas back pressuresensor, the CDI control unit (N3/9) candistinguish between a higher back pressure and amalfunction.

The exhaust gas back pressure sensor is locatedat the left rear of the engine compartment, in theexhaust gas recirculation channel in front of theexhaust gas recirculation positioner (Y27/9).

P07.04-2204-02 P07.16-2537-14


Throttle valve actuator (M16/5)

P14.20-2111-02 P14.20-2110-01

The throttle valve actuator (M16/5) is actuated bya PWM signal from the CDI control unit (N3/9),and controls the quantity of fresh air by means ofthe throttle valve (1).

The throttle valve actuator is active during theregulating phase, to assist the recirculation ofwarm exhaust gases. This helps the catalyticconverter to warm up.

The fresh intake air is mixed with the recirculatedexhaust gas by means of the exhaust gasrecirculation connection with mixing throttle (3).The pressure for the pressure sensor (intakemanifold) is taken from the pressuremeasurement connection (2).

The throttle valve actuator is located at the leftfront of the engine compartment (Model 211), infront of the intake manifold.

1 Throttle valve2 Pressure measurement connection for the pressure sensor (intake manifold)3 Exhaust gas recirculation connection with mixing throttle4 Electrical connectionM16/5 Throttle valve actuator


Regeneration (self-cleaning)

The self-cleaning process of the diesel particulate filter is performed automatically by the CDI control unit (N3/9). This is done according to the values measuredat the differential pressure sensor (B28/8), but every 1000 km at least. The CDI control unit (N3/9) burns off the particulates deposited in the filter by raisingthe exhaust gas temperature.The regeneration process can be interrupted by the CDI control unit (N3/9), and restarted later (for example, if the engine is switched off).

To start the regeneration process, boththe minimum and maximum conditionsmust be present.

Maximum conditions:� Differential pressure in the diesel particulate filter� Mileage (km)

RegenerationMinimum conditions:� Vehicle speed > 10 km/h� Exhaust gas temperature > 150°C� Tank fill level > Reserve� Operating point Idle up to 4000 rpm� No related fault entry in the CDI control unit


Duration of regeneration

Depending on exhaust gas temperature, theregeneration phase lasts between 400 and1000 seconds.

normal

off

on

regeneration

Filter full (soot)Filter empty

Post-injectionSoot burned off Ash detection

Full regeneration


Burn-off process

Additional fuel is injected into the cylinder during the discharge stroke and burned off in the TWC. The very hot exhaust gases thus ignite the soot in the dieselparticulate filter � the soot burns (in the same way as a grill is ignited by a heat gun).If the customer never drives the vehicle in these conditions, the process must be carried out at the workshop.

The customer is informed of this by a message on the instrument cluster.This message may indicate:� Diesel particulate filter full of soot (regeneration required)� Diesel particulate filter full of ash (filter exchange required)

Measures during the burn-off process:� Post-injection� Exhaust gas recirculation de-activated� Intake air throttling� Boost pressure control� Increase in load: heater booster (depending on battery charge level) and suction fan (100 %) switched

on� Driver message "Air conditioning ON" if necessary

GT14_40_0009_C71


Useful life and replacement

GT14_40_0010_C71

It is not possible to burn off soot deposits without leaving residues. At each burn-off process, alayer of ash is left on the particulate filter. The diesel particulate filter must therefore be replacedat the appropriate intervals.At the 80,000 km maintenance service, the ash content in the filter is measured and the length oftime for which the filter can be left in the vehicle is calculated using a formula (see maintenancesheet).

A DPF is a genuine reconditioned part, which has passed through the existing Mercedes-Benzreconditioning process for original replacement parts.

Parts information (for example, for model series 203)Part number ScopeA203 490 00 92 80 Particulate filter, reconditioned (bottom section)A203 490 00 92 Particulate filter, new (bottom section)A203 490 84 14 80 Oxidation catalytic converter, reconditioned (upper section)A203 490 84 14 Oxidation catalytic converter, new (upper section)A203 490 83 14 80 Oxidation catalytic converter/ particulate filter assembly,

reconditionedA203 490 83 14 Oxidation catalytic converter/ particulate filter assembly, new

The removed diesel particulate filter is re-conditioned (cleaned) by a specialized firm. This processcannot be carried out by the user.

a Soot depositsb Ash deposits

b

a


Engine oil

A special engine oil has been developed with ExxonMobil for EURO 4 engines with diesel particulate filter (see Specifications for Operating Fluids, Sheet 229.31),which produces less combustion residues (and therefore ash) during operation, thus ensuring a long useful life for the filter.This oil is for vehicles of the BR203 and BR211 series with SA "factory fill" Code 474, and therefore absolutely essential for maintenance operations.The customer can perform oil refills with the oils indicated on Sheet 229.3 and Sheet 229.5 (see SI14.40-P-0001A).

Part number ScopeA000 989 89 01 10 1 liter container of "low SPAsh" engine oil

Oil dilution

If the vehicle is used exclusively for short trips, or the urban cycle, oil dilution may result due to continualinterruption of regeneration process.Nevertheless, the message shown opposite may be shown in relation to the exhaust system, if� the customer has not refilled with oil� the customer uses the vehicle only for short trips.

In this case, the oil should be changed.GT14_40_0011_C71

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR CDI control unit 60

CDI control unit 05.03.2004

P07.16-0234-01

Function

The CDI control unit (N3/9) controls the following systems according to evaluation of the input signals:� Fuel supply� Injected fuel quantity control� Emission control system� Boost pressure control - cruise control (AT only)� AC compressor shutoff� Diesel particulate filter functions

It performs the following functions:� Monitors inputs/outputs� Signal plausibility check� Stores errors� Generates substitute values if signals fail (emergency mode)� Diagnosis (readout of stored faults)

� Control units are seldom faulty, and are often replaced unnecessarily. It is therefore indispensableto eliminate all the other possible faults before replacing an expensive control unit. Please contactyour local Hotline, and follow their advice first!

SCN coding

From 2003 onwards, all engine control units must be SCN encoded, in order to detect or prevent anytampering with the software.


Function diagram (M646 with DPF)

P07.16-2545-79


110 Turbocharger110/2 Charge air cooler114 Diesel particulate filter (DPF)120/1 Oxidation catalytic converter (near-engine mounted)120/2 Oxidation catalytic converter (underfloor)B2/5 Hot film MAF sensorB2/5b1 Intake air temperature sensorB4/6 Rail pressure sensorB6/1 Camshaft Hall sensorB11/4 Coolant temperature sensorB17/8 Charge air temperature sensorB19/7 TWC temperature sensorB19/8 Temperature sensor after TWCB28 Charge air pressure sensorB28/5 Pressure sensor after air cleanerB28/8 Differential pressure sensor of diesel particulate filterB37 Accelerator pedal sensorB40 Oil sensor (oil level, temperature, quality)B50 Fuel temperature sensorB60 Exhaust back pressure sensor

G3/2 Oxygen sensor before TWCK40/5kTL5 Crankshaft position sensorM3M4/7M16/5 Throttle valve actuatorM55 Engine intake port shutoff (Engine 646, 647 only)N3/9 CDI control unitN10/2kAN14/2 Glow output stageN33/2R9 Pencil-type glow plugsR39/1S40/3Y27/9 Exhaust gas recirculation positioner, leftY74 Pressure regulator valveY94 Quantity control valveY76y1-y4 Fuel injectors, cylinders 1-4Y100/1 Right boost pressure regulator

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR European On-Board Diagnosis (EOBD) on CDI engines 63

European On-Board Diagnosis (EOBD) on CDI engines 05.03.2004

0100 Star DiagnosisA1 Instrument clusterA1e26 CHECK ENGINE indicator lampA1e58 Engine diagnosis indicator lampN3/9 CDI control unitX11/4 Diagnosis test connectorCAN Data bus (Controller Area Network)

P07.16-2443-11

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR European On-Board Diagnosis (EOBD) on CDI engines 64

EOBD is the acronym for European On-Board Diagnosis, i.e. the integratedon-board diagnostic systems installed in vehicles.

The diagnostic system integrated in the CDI control unit (N3/9) monitorsall exhaust related components and subsystems.The engine diagnosis indicator lamp (A1e58) is used to display any faultsthat are detected. The engine diagnosis indicator lamp is actuated:� when the ignition is ON, before the engine is started (goes off after the

engine is started, if no faults are detected).� if there is a fault in an exhaust related component or system.

If there is a fault (for example in the exhaust gas recirculation), it isindicated by the indicator lamp on the instrument cluster. The fault is alsostored in the CDI control unit.

The CDI control unit checks its inputs and outputs for plausibility.

The following data and functions can be read out:� Fault freeze frame data� Exhaust related error codes� Results of tests on continuously monitored systems� Instantaneous diagnostic data

Readiness CodeThe Readiness Code indicates that tests are running in order to detectfaults in various components or functions. This check is carried out atleast once each time the engine is started. If a fault is detected, substitutevalues are created and the engine diagnosis indicator lamp is lit.When the ignition is OFF, an internal circuit ensures a run-on period duringwhich the CDI control unit continues to function. During the run-on period,system tests are carried out and the fault memory is updated.

The monitored functions and data depend on the vehicle and enginevariants, and therefore varies according to the individual vehicle models.For vehicles with diesel engines, OBD is compulsory starting from2004 (in accordance with EU Guideline 1999/102/EG).

EOBD therefore began to be installed in all Mercedes-Benz passengervehicles with diesel engines during the year 2003.

An additional "Readiness codes" test stage is included in the DAS on the"Control Units" submenu.

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR CAN Data Bus 65

CAN Data Bus 05.03.2004

General What does acronym "CAN" stand for? Control Area Network

The CAN is a computer network installed inside the vehicle, which allows communication between thedifferent control units. The data line between the control units is called the CAN Bus. It is used toexchange information between control units (in the same way as a tube conveyor), carrying digitalencoded data addressed to certain receiver units. There are various kinds of CAN buses, which operate atdifferent transfer rates.

Function � Data exchange between the individual control units� Provide the sensor signals for various systems� Reduce the number of electric cables� Improve electromagnetic compatibility

Design For security (in case of data line faults, signal interference), signals are transferred on two lines, but withopposite signs. In principle, one data line would be enough.

The CAN bus consists of a twisted pair data line, which connects all CAN participants (control units)together in parallel.

The data lines (Low / High voltage states) should not be interchanged.

Operation The data are transferred in digital form over the CAN bus at varying intervals. The individual data blocksare defined by protocols, establishing which data are sent or received from which control unit. Anycontrol unit connected to the bus can send or receive data.

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Synchronization 66

Synchronization 05.03.2004

Signal forms In the vehicle, data is sent using various signal forms.Each signal form depends partly on technical factors, and partly on the current function.The following paragraphs describe the signal forms for the synchronization.

Description

Sine wave signalThe sine wave signal is an oscillating signal, which varies continuously over time, around a constant value.

Where usedCrankshaft position sensor (L5)

Description

Square wave signalThe square wave signal is a signal with an on/off phase that remains constant over time

Where usedCamshaft Hall sensor (B6/1)

V

t

V

t


Diesel engines synchronization

Function

When the engine is started, the ignition TDC for cylinder 1 is detected from the signals from thecrankshaft position sensor (L5) and camshaft Hall sensor (B6/1).

Operation

When the crankshaft is turning, the teeth on the increment wheel generate an AC voltage in thecrankshaft position sensor. At the gap where there are two missing teeth (c), no voltage is generated. Atthe second negative edge after the gap, the engine control unit detects the top dead center (TDC)position of cylinder 1 and 4 (on 4-cylinder engines).

P07.04-2024-76

At this point, if signal (a) from the camshaft Hall sensor (B6/1) is at 0 V, the engine control unit detectsthe ignition TDC for cylinder 1.

The synchronization signals are also processed by the CDI control unit (N3/9) in order to actuate theinjectors (Y76).

�The engine cannot run without the signal from the crankshaft position sensor (L5). If the signal from thecamshaft Hall sensor (B6/1) is missing, the engine does not start.

P07.16-2238-06


Signal representation (Engine 646)

1 Crank angle2 Cylinder ignition TDC3 Signal from crankshaft position sensor (L5)

4 Signal from camshaft Hall sensor (B6/1) P07.60-0289-08

5 TNA rpm signal

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Heater booster (HB) 69

Heater booster (HB) 05.03.2004

P83.70-3140-11

Shown in the M628

FunctionAn electrical heater booster is installed in CDI engines, in order to compensate for the lower heat outputdue to the high degree of efficiency.

DesignThe fuel heater booster is similar to a stationary heater. It is controlled by the CDI control unit (N3/9)according to engine temperature.The electric heater booster in the coolant consists of a heating element and the heater booster controlunit (N33/2) attached directly to it. Here too, the CDI control unit (N3/9) is ‘boss’.PTC heater boosters in the air flow of the heating and air conditioning system heat the vehicle interioraccording to the heating and air conditioning control unit only (for example, in the W211).

Electric heater booster in the coolantThe heater booster control unit receives the alternator load signal from the alternator controller. In thisway, the heater booster control unit detects alternator excess output, which is not currently needed bythe on-board electrical system. The heater booster control unit transmits this excess power to the heatingelement. The heat energy is fed into the coolant circuit. No load is placed on the battery.If a fault is detected, heat output is set at ‘zero’.

Pre-conditions for actuation:� Engine running� “Automatic” operation selected on the multifunction display or “With E/C button off” selected on the

multifunction display (heater booster switched on with the E/C button)� Outside temperature � 8°C� Coolant temperature < 78°C

The switch-on temperatures can be changed on the STAR Diagnosis system or the instrument cluster inthe corresponding menu (see Chapter “Vehicle settings for test purposes”).

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Heater booster (HB) 70

Overview of the various heater boosters and fuel cooling systems

Coolant

alter-nator

Electricheater

booster onwheelhouse

Electricheater

booster atengine

Fuel operatedboosterheater

Fuelpreheating

with coolant

Fuelpreheatingwith fuel

PTC heatingresistor forcrankcaseventilation

Fuel coolingwith coolant

Air-cooledfuel cooler

A-Class with CDI 1 up tomodel refinement package2001

X X X

A Class with CDI 1 frommodel refinement package2001

X X

C-Class (W203) X X X X X

E-Class (W210) with CDI 1 X X

E-Class (W210) with CDI 2 X X from09/2000

up to08/2000

X X X

ML 270 CDIwith CDI 2

X X X X

S 320 CDIwith CDI 2

X X X X X X

S 400 CDIwith CDI V1

X X X X

E-Class (W211)with CDI 3

X

E-Class (W211) with CDIV1

X X

PTC for warming the interior installed in theheater housing.


Coolant-heated

Coolant-heated

Coolant-heated



03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Vehicle settings for test purposes 71

Vehicle settings for test purposes 05.03.2004

Roller dynamometer mode � You can activate roller dynamometer mode on the instrument cluster using the multifunction steeringwheel and multifunction display.

1. Turn ignition key to Position "1".

2. Press and hold the Reset button on the left of the instrument cluster (for about 20 sec) until a beepis heard.

3. Press the "Previous system" button once.

4. Press the "Previous system display" arrow key on the steering wheel once.The roller dynamometer mode appears on the display.

5. Press the "+" key on the right of the steering wheel once. Roller dynamometer mode isactivated and indicates ON.The vehicle can now be driven on the roller without being regulated by the ESP (electronic stabilityprogram)!

6. To switch off Test Mode, turn the ignition key to Position “1” press the minus key once, thenswitch off Test Mode. The display shows "With KL 15 OFF". When the ignition is switched "OFF", rollerdynamometer mode is deactivated again.

P82.90-2051-06

Note:No errors in the ESP or engine control unit are stored after switching the roller dynamometer mode on/off. (AR54.30-P-1000-01A)

From 08/2002, roller dynamometer mode is activated as follows for models 203, 209, 215 and 220:� Ignition key at Position 1� Within 2.5 seconds, press the reset button 3 times� Using the up/down arrow buttons, the battery charge level and the instrument panel software release can then be viewed, and the ESP roller dynamometer

mode menu activated/deactivated;the Oil Level indicator and Engine Model can be displayed on the "Software release" screen by turning the ignition key to position “2”

� From 03/2003 onwards, this procedure also applies to Models 211 and 230

03/04 Passenger cars • Engine Common Rail Diesel Injection (CDI) Specialist training Information moduleTR Safety concept diesel engine 72

Safety concept diesel engine 05.03.2004

Model / Series Fuse Diagnostic equipment Effect on vehicle Fault code

A-Class / W168 F1f1 Ignition ON Suction fan runs P 1636; P 1403; P 0100; P 1615;P 1482

F1 f2 Ignition ON Suction fan runs --C Class / W203 N10/1 f53 SAM left front CDI does not respond Starter does not turn --

N10/1 f54 SAM left front -- Suction fan runs, coolantwarningEngine in Emergency Mode,EPC warning

All peripheral components indiagnostic trouble code memory

E-Class / W210 K40/4 f1 SRB passenger CDI does not respond Starter does not turn --K40/4 f2 SRB passenger Communication lost Suction fan runs,

coolant warningEngine in Emergency Mode,EPC warning

All peripheral components indiagnostic trouble code memory butonly after repair

E-Class / W211 f42 Light module Communication error Engine OFFSuction fan runs

--

N10/1 f43 SAM left front -- Engine OFF P 2502; P 2100; P 1615N10/1 f44 SAM left front -- Emergency Mode P 2199; P 0100; P 2514; P 2120N10/1 f57 SAM left front -- Engine OFF P 2123N10/2 f4 SAM left rear -- Engine OFF P 2021

S-Class / W220 N40/7 f43 SAM right front Communication error Engine OFFSuction fan runs

P 2004

N40/7 f44 SAM right front -- Engine stops under load P 2015; P 2018; P 2021; P 2021;P 2023; P 2035

K40/5 f52 -- Engine OFF --

DaimlerChrysler AGGlobal TrainingHPC T301D-70546 Stuttgart

Intranet: http://intra-gt.daimlerchrysler.com

» ... Die Mitarbeiter werden zukünftig in die Rolle persönlicher Wissensmanager hineinwachsenmüssen, die aktiv die Verantwortung für ihre Qualifizierung übernehmen ... « Jürgen E. Schrempp

» ... Staff must in future assume the role of personal knowledge managers, who actively takeresponsibility for their own qualification ... « Jürgen E. Schrempp

��

1511 1120 00 - 2. Edition 03/04 78 Stand 01/04.

engine cdi

Documents