1.9-ltr. TDI Engine with Pump Injection System - Volkswagen ...

Table of contentsIntroduction ..................................................................Specifications4Pump injection system ................................................. 6GeneralStructural designDriving mechanismInjection cycleFuel supply ...................................................................Diagram of fuel circuitFuel pumpDistributor pipeFuel cooling system18Engine management ................................................... 26System overviewSensorsActuatorsGlow plug systemFunction diagramSelf-diagnosisEngine mechanicals ....................................................Trapezoidal piston and conrodToothed belt drive51Service ........................................................................... 54Special tools3

Introduction1.9-ltr. TDI engine with pump injection systemIt was developed on the basis of the 1.9-ltr./81kW TDI engine with no intermediate shaft.Only through the injection system does it differfrom the engine fitted with a distributorinjection pump.On the following pages we will explaineverything about the design and the mode offunctioning of the pump injection system andwe will show you the necessary modificationsto the fuel system, engine management systemand engine mechanicals.209_05The diesel engine with the pump injection systemhas the following advantages over the distributorinjection pump:• Low combustion noise• Low fuel consumption• Clean emissions• High efficiencyThese advantages are attributable to:• The high injection pressures of up to 2050 bar• Precise control of the injection cycle• The pre-injection cycle4

SpecificationsEngine code:Type:Stroke/bore:AJM4-cylinder in-line engine79.5mm/ 95.5mmCompression ratio: 18 : 1Mixture preparationEngine management:Fuel type:Electronic Diesel Control,Bosch EDC 15 PDiesel, at least 49CN,or biodiesel (RME)Exhaust gasaftertreatment:Output and torque curveExhaust gas recirculationand oxidation catalyticconverterThe engine conforms to exhaustemission level D3.Comparative torque curveTorqueNm85 KWPower outputkW300TorqueNm300285 Nm8025025070200200601501505010010040800 1000 2000 3000 4000 5000Engine speed (rpm)02000 4000 6000Engine speed (rpm)1.9-ltr. 85kW TDI engine209_061.9-ltr. 81kW TDI engine209_11Thanks to the high injection pressures up to 2050bar and the favourable effect they have on thecombustion process, the engine develops 285Nmof torque at only 1900rpm.Maximum power output is 85kW at 4000rpm.From the same displacement, the engine withpump injection system develops 21% moretorque than the 1.9-ltr. 81kW TDI engine withdistributor injection pump.5

Pump injection systemGeneral informationWhat is a pump injector?A pump injector is, as the name already implies,an injection pump combined with a control unitand an injector.Each cylinder of the engine has a pump injector.This means that there is no longer any need for ahigh-pressure line or a distributor injection pump.Just like a distributor injection pump withinjectors, the pump injection system has thefollowing tasks:• Generating the high injection pressuresrequired• Injecting fuel in the correct quantity and atthe correct point in timePressuregeneratingpumpInjectorControl unit(solenoid valve)209_126

Fitting locationThe pump injector is directlyintegrated in the cylinder head.209_86FixingIt is attached to the cylinder head by a clamping block.It is important to ensure that the pump injector isinstalled in the correct position.If the pump injector is not perpendicular to thecylinder head, the fastening bolt can comeundone. The pump injector and/or the cylinderhead may be damaged as a result. Pleaseobserve the instructions given in the WorkshopManual.209_877

Pump injection systemDesignRoller-typerocker armBall pinPump pistonPiston springInjection camSolenoid valveneedleInjectorsolenoid valveHigh-pressure chamberFuel return lineRetraction pistonFuel supply lineO-ringsInjectorspringInjector needledamping elementHeatinsulatingsealInjectorneedle209_23Cylinder head8

Drive mechanismThe camshaft has four additionalcams for driving the pump injector.They activate the pump pistons ofthe pump injector via roller-typerocker arms.Injection camValve camRoller-typerocker arm209_15The injection cam has asteep leading edge. . .. . . and a flat trailing edge.As a result, the pump piston is pushed down athigh velocity and a high injection pressure isattained quickly.As a result, the pump piston moves up and downslowly and evenly, allowing fuel to flow free ofair bubbles into the high-pressure chamber ofthe pump injector.Roller-type rocker armRoller-type rocker armPumppistonPumppistonInjection camInjection cam209_16 209_179

Pump injection systemRequirements relating to mixture formation and combustionGood mixture formation is a vital factor to ensureefficient combustion.Accordingly, fuel must be injected in the correctquantity at the right time and at high pressure. Evenminimal deviations can lead to higher levels ofpollutant emission, noisy combustion or high fuelconsumption.A short firing delay is important for the combustionsequence of a diesel engine. The firing delay is theperiod between the start of fuel injection and the startof pressure rise in the combustion chamber. If a largefuel quantity is injected during this period, thepressure will rise suddenly and cause loudcombustion noise.Pre-injection cycleTo ensure the combustion process is as soft aspossible, a small amount of fuel is injected at a lowpressure before the start of the main injection cycle.This injection process is known as the pre-injectioncycle. Combustion of this small quantity of fuel causesthe pressure and temperature in the combustionchamber to rise.This meets the requirements for quick ignition of themain injection quantity, thus reducing the firing delay.The pre-injection cycle and the "injection interval"between the pre-injection cycle and the main injectioncycle produce a gradual rise in pressure within thecombustion chamber, not a sudden pressure build-up.The effects of this are low combustion noise levels andlower nitrogen oxide emission.Main injection cycleThe key requirement for the main injection cycle is theformation of a good mixture, the aim being to burnthe fuel completely if possible. The high injectionpressure finely atomises the fuel in such a way that thefuel and air can mix well with one another. Completecombustion reduces pollutant emission and ensureshigh engine efficiency.End of injectionAt the end of the injection process, it is important thatthe injection pressure drops quickly and the injectorneedle closes quickly. This prevents fuel at a lowinjection pressure and with a large droplet diameterfrom entering the combustion chamber. The fuel doesnot combust completely, giving rise to higher pollutantemissions.The injection curve of the pump injection system largelymatches the engine's demands, with low pressuresduring the pre-injection cycle, followed by an "injectioninterval", then a rise pressure during the main injectioncycle. The injection cycle ends abruptly.InjectionpressureEngine demandTimePump injector10

The injection cycleThe high-pressure chamber is filledRoller-type rocker armDuring the filling cycle, the pump piston movesupwards under the force of the piston spring andthus increases the volume of the high-pressurechamber.The injector solenoid valve is not activated.The solenoid valve needle is in its resting positionand opens up the path from the fuel supply lineto the high-pressure chamber. The fuel pressurein the supply line causes the fuel to flow into thehigh-pressure chamber.Pump pistonPiston springSolenoid valve needleHigh-pressurechamberInjectorsolenoid valveFuel supply line209_2411

Pump injection systemThe injection cycleThe pre-injection cycle commencesThe injection cam pushes the pump piston downvia the roller-type rocker arm and thus displacesfuel out of the high-pressure chamber into thefuel supply line.The engine control unit initiates the injectioncycle by activating the injector solenoid valve. Inthe process, the solenoid valve needle is presseddown into the valve seat and closes off the pathfrom the high-pressure chamber to the fuelsupply line. This initiates a pressure build-up inthe high-pressure chamber. At 180 bar, thepressure is greater than the force of the injectorspring. The injector needle is lifted and the preinjectioncycle commences.Pump pistonSolenoid valveseatInjection camSolenoid valve needleHigh-pressurechamberFuel supply lineInjector needle209_2512

The pre-injection cycle commencesInjector needle dampingDuring the pre-injection cycle, the stroke of the injectorneedle is dampened by a hydraulic 'cushion'. As a result, it ispossible to meter the injection quantity exactly.This is how it works:In the first third of the total stroke, the injector needle isopened undamped. The pre-injection quantity is injected intothe combustion chamber.UndampedstrokeAs soon as the damping piston plunges into the bore in theinjector housing, the fuel above the injector needle can onlybe displaced into the injector spring chamber through aleakage gap. This creates a hydraulic 'cushion' which limitsthe injector needle stroke during the pre-injection cycle.209_35Injector springchamberInjector housingLeakage gapHydrauliccushionDamping piston209_3613

Pump injection systemThe injection cycleEnd of pre-injection cycleThe pre-injection cycle ends straight after theinjector needle opens. The rising pressure causesthe retraction piston to move downwards, thusincreasing the volume of the high-pressurechamber.The pressure drops momentarily as a result, andthe injector needle closes.This pre-injection cycle now ends.The downward movement of the retraction pistonpre-loads the injector spring to a greater extent.To re-open the injector needle during thesubsequent main injection cycle, therefore, thefuel pressure has to be higher than during thepre-injection cycle.Pump pistonHigh-pressurechamberInjectorsolenoid valveRetractionpistonInjectorspringInjector needle209_2614

The injection cycleThe main injection cycle commencesThe pressure in the high-pressure chamber risesagain shortly after the injector needle closes.The injector solenoid valve remains closed andthe pump piston moves downwards.At approx. 300 bar, the fuel pressure is greaterthan the force exerted by the pre-loaded injectorspring. The injector needle is again lifted and themain injection quantity is injected.The pressure rises to 2050 bar, because morefuel is displaced in the high-pressure chamberthan can escape through the nozzle holes.Maximum. fuel pressure is at max. engine output,i.e. at a high engine speed with a large quantityof fuel being injected at the same time.Pump pistonHigh-pressurechamberInjectorsolenoid valveInjectorspringInjector needle209_2715

Pump injection systemThe injection cycleThe main injection cycle endsThe injection cycle ends when the engine controlunit stops activating the injector solenoid valve.The solenoid valve spring opens the solenoidvalve needle, and the fuel displaced by thepump piston can enter the fuel supply line. Thepressure drops. The injector needle closes andthe injector spring presses the bypass piston intoits starting position.The main injection cycle now ends.Pump pistonSolenoid valve springSolenoid valve needleInjectorsolenoid valveRetractionpistonFuel supply lineInjector needle209_2816

Fuel return in the pump injectorThe fuel return line in the pump injector has thefollowing task:• Cool the pump injector. For this purpose, fuelfrom the fuel supply line is flushed throughthe pump injector ducts into the fuel returnline.• Discharge leaking fuel at the pump piston.• Separate vapour bubbles from the fuelsupply line via the restrictors in the fuel returnline.Leaking fuelPump pistonRestrictorsFuel return lineFuel supply line209_9617

Fuel supplyThe fuel systemA mechanical fuel pump sucks the fuel out of thefuel tank through the fuel filter and pumps italong the supply line in the cylinder head to thepump injector units.The fuel which is not required for injection isreturned to the fuel tank via the return line in thecylinder head, a fuel temperature sensor and afuel cooler.The fuel temperature sensordetermines the temperature of the fuel inthe fuel return line and sends acorresponding signal to the engine controlunit.The fuel coolercools the returning fuel to protect thefuel tank against excessively hot fuel.The fuel tank209_18The fuel filterprotects the injection systemagainst contamination and wearcaused by particles and water.The non-return valveprevents fuel from the fuel pumpflowing back into the fuel tank whilethe engine is not running (openingpressure=0.2 bar).18

The bypassThe pressure limiting valveIf there is air in the fuel system, for examplewhen the fuel tank is empty, the pressurelimiting valve remains closed. The air isexpelled from the system by the fuel flowinginto the tank.keeps the pressure in the fuelreturn line at 1 bar. A forceequilibrium is thereby maintainedat the solenoid valve needle.The cylinder headThe restrictor bore from the fuel supply line to the fuel return lineVapour bubbles in the fuel supply line are separated in the fuel returnline through the restrictor bore.The fuel pumpThe pressure limiting valveregulates the fuel pressure in the fuelsupply line. The valve opens when thefuel pressure exceeds 7.5 bar,and fuel is fed to the suction side ofthe fuel pump.pumps the fuel from the fuel tank via thefuel filter to the pump injector.The strainerhas the task of collecting vapour bubbles fromthe fuel supply line. These vapour bubbles arethen separated through the restrictor bore andreturn line.19

Fuel supplyThe fuel pumpThe fuel pump is located directlybehind the vacuum pump at thecylinder head. It has the task ofconveying the fuel from the fuel tankto the pump injector.Both pumps are driven jointly by thecamshaft, which is why they arecollectively known as a tandempump.Fuel return lineVacuumpumpFuel pumpFuel supply lineConnectionfor pressuregauge209_49There is a connection for pressure gauge V.A.S. 5187 on the fuel pump for checking the fuelpressure in the supply line. Please observe the instructions in the Workshop Manual.The fuel pump is a blocking vane-cellpump. With this type of pump, theblocking vanes are pressed againstthe rotor by the spring pressure. Theadvantage of this is that the pumpdelivers fuel even at low enginespeeds. Rotary vane pumps do notprime until the engine is running sofast that the vane cells are pressedagainst the stator by centrifugal force.The fuel ducting system within thepump is designed so that the rotoralways remains wetted with fuel evenif the tank has been run dry. Thismakes automatic priming possible.Pressure regulatingvalve for fuel supplylineConnection forfuel supply lineFrom the returnline in thecylinder headRotorBlocking vanesRestrictorStrainerIn the supply linein the cylinderheadConnection for fuelreturn linePressure regulatingvalve for fuel returnline209_5020

This is how it works:The fuel pump operates by intaking when thevolume increases and delivering when thevolume reduces.The fuel is drawn and pumped into twochambers. The intake chambers and feedchamber are separated from one another by theblocking vanes.In this figure, fuel is drawn out of chamber 1 andpumped out of chamber 4. The rotationalmovement of the rotor increases the volume ofchamber 1 while the volume of chamber 4reduces.Chamber 4Chamber 1Rotor209_52In this figure, the other two chambers are inaction. The fuel is pumped out of chamber 2 anddrawn out of chamber 3.Chamber 3Chamber 2209_5121

Fuel supplyThe distributor pipeA distributor pipe is integrated in thesupply line in the cylinder head. It hasthe task of distributing fuel evenly to the pumpinjectors.209_40Cylinder1Cylinder2Cylinder3Cylinder4Cylinder headAnnulargapCross holesDistributor pipe209_39This is how it works:The fuel pump conveys the fuel into the supplyline in the cylinder head.In the supply line, the fuel flows along the innerside of the distributor pipe towards cylinder 1. Thefuel enters the annular gap between thedistributor pipe and the cylinder head wallthrough cross-holes. Here, the fuel mixes with thehot fuel forced back into the supply line by thepump injectors. As a result, the fuel in the supplyline running to all cylinders has a uniformtemperature. All pump injectors are supplied withthe same fuel mass, and the engine runssmoothly.Mixingof the fuelin the annulargapCross boresFuel from pumpinjectorFuel to pumpinjector209_2922

Without a distributor pipe, the fuel temperatureat the pump injector would not be uniform.The hot fuel forced back into the supply line bythe pump injector is pushed from cylinder 4towards cylinder 1 by the flowing fuel into thesupply line.As a result, the fuel temperature rises fromcylinder 4 to cylinder 1 and the pump injectorsare supplied with different fuel masses. Theeffects of this would make the engine runirregularly and would cause an excessively hightemperature in the front cylinders.Cylinder1Cylinder2Cylinder3Cylinder4Cylinder headAnnulargap209_10223

Fuel supplyThe fuel cooling systemThe high pressure in the pump injector heats upthe fuel so intensively that it has to be cooleddown before it flows back into the fuel tank.A fuel cooler is located on the fuel filter.It cools the returning fuel and thus protects thefuel tank and the fuel level sender againstexcessively hot fuel.Fuel coolerFuel pumpCoolant senderExpansion tank209_42Auxiliary water coolerFuel cooling pump24

The fuel cooling circuitThe fuel returning from the pump injector flowsthrough the fuel cooler and transfers its hightemperature to the coolant in the fuel coolingcircuit.The fuel cooling circuit is separate from theengine cooling circuit. This is necessary since thetemperature of the coolant is too high to cooldown the fuel when the engine is at operatingtemperature engine.The fuel cooling circuit is connected to the enginecooling circuit in the vicinity of the expansiontank. The fuel cooling circuit can thus be filledand changes in volume due to temperaturefluctuation can be compensated. The fuel coolingcircuit is connected so that the hotter enginecooling circuit does not have a detrimental effecton the fuel cooling circuit.Fueltemperature senderThe fuel coolerThe fuel and coolant flows through the fuelcooler. The temperature of the fuel istransferred to the coolant.Fuel tankFuel pumpExpansion tank209_48The auxiliary water coolerreduces the temperature of the coolantin the coolant circuit. It dissipates theheat of the coolant to the ambient air.The fuel cooling pumpis an electrical recirculation pump which circulates thecoolant in the fuel cooling circuit. It is switched on bythe engine control unit via the fuel cooling pump relayat a fuel temperature of 70°C.Engine coolingcircuit25

Engine managementSystem overviewAir-mass flow meterG70Altitude sender F96Engine speed sender G28Hall sender G40Accelerator position sender G79Kick-down switch F8Idling speed switch F60Coolant temperature sender G62Diagnosis wireand immobiliser wireIntake manifold pressure sender G71Intake manifold temperature sensor G72Clutch pedal switch F36CAN databusBrake light switch Fand brake pedal switch F47Fuel temperaturesender G81Auxiliary signals:Road speed signalAir conditioner compressor readyCCS switch3-phase AC alternator terminal DFABS control unit J10426

Glow plugs Q6Control unitfor diesel directinjection system J248Glow plug relayJ52Pumpinjector valves,Cylinders 1-4N240 - N243Glow periodwarning lampK29EGR valve N18Solenoid valvefor charge pressurecontrol N75Change-over valvefor intake manifold flapN239Pump relay,fuel cooling J445Fuel coolingpumpV 166Automatic gearbox controlunit J217Auxiliary signals:Coolant auxiliary heaterEngine speedCooling fan run-onAir conditioner compressor cut-offFuel consumption signal209_5327

Engine managementSensorsHall sender G40Camshaft senderwheelThe Hall sender is attached to the toothed beltguard below the camshaft gear. It scans seventeeth on the camshaft sender wheel attached tothe camshaft gear.Hallsender209_54Signal utilisationThe engine control unit uses the signal which the Hall sendergenerates to recognise the cylinders when starting the engine.Effects of signal failureIn the event of signal failure, the control unit utilises the signalwhich the engine speed sender G28 generates.Electrical circuitJ 317SJ248G40209_5528

Cylinder recognition when starting the engineWhen starting the engine, the engine control unitmust know what cylinder is in the compressionstroke in order to activate the correct pumpinjector valve. For this purpose, it evaluates thesignal generated by the Hall sender, which scansthe teeth of the camshaft sender wheel and thusdetermines the camshaft position.The camshaft sender wheelSince the camshaft executes one 360° revolutionper working cycle, there is a tooth for eachindividual cylinder on the sender wheel; theseteeth are spaced 90° apart.To enable the teeth to be assigned to thecylinders, the sender wheel has an additionaltooth for cylinders 1, 2 and 3 with differentspacings.Cylinder 4Cylinder 3Cylinder 190°This is how it works:Cylinder 2209_94Each time a tooth passes the Hall sender, a Hallvoltage is induced and transmitted to the enginecontrol unit. Because the teeth are spaced atdifferent distances apart, the Hall voltages occurat different time intervals.From this, the engine control unit recognises thecylinder and can control the correct injectorsolenoid valve.Signal pattern, Hall sender90° 90° 90° 90°Cylinder 1Cylinder 3Cylinder 4Cylinder 2Cylinder 1209_9529

Engine management systemEngine speed sender G28The engine speed sender is an inductive sender. It is attached tothe cylinder block.209_56Engine speed sender wheelThe engine speed sender scans a 60-2-2 sender wheel attachedto the crankshaft. The sender wheel has 56 teeth and 2 gaps of 2teeth on its circumference. The gaps are offset by 180°and serveas a reference mark for determining the crankshaft position.209_85Signal utilisationThe signal generated by the engine speed sender records theengine speed and the exact position of the crankshaft. Theinjection point and the injection quantity are calculated usingthis information.Effects of signal failureIf the signal of the engine speed sender fails, the engine isturned off.Electrical circuitJ248G28209_5730

FunctionQuick start recognitionTo allow the engine to be started quickly, the engine control unitevaluates the signals generated by the Hall sender and theengine speed sender.The engine control unit recognises the cylinder from the signalgenerated by the Hall sender which scans the camshaft senderwheel. Due to the 2 gaps on the crankshaft sender wheel, theengine control unit receives a reference signal after only half aturn of the crankshaft. In this way, the engine control unit canrecognise the position of the crankshaft in relation to thecylinders at an early stage and activate the correct solenoidvalve to initiate the injection cycle.Signal pattern, Hall sender and engine speed sender1 camshaft revolutionCylinder 1 Cylinder 3 Cylinder 4Cylinder 2Signal generatedby Hall sender1 crankshaft rotationSignal generatedby engine speedsender209_9531

Engine managementFuel temperature sender G81The fuel temperature sender is a temperature sensor with anegative temperature coefficient (NTC). This means that thesensor resistance decreases with increasing fuel temperature.This sensor is located in the fuel return line running from the fuelpump to the fuel cooler and determines the current fueltemperature.209_43Signal utilisationThe signal generated by the fuel temperature sender is used torecognise the fuel temperature.The engine control unit requires this signal to calculate thecommencement of injection point and the injection quantity sothat it can make allowance for the density of the fuel at differenttemperatures. In addition, the signal is utilised as information forswitching on the fuel cooling pump.Effects of signal failureIn the event of signal failure, the engine control unit calculates asubstitute value from the signal generated by coolanttemperature sender G62.Electrical circuitJ248G81209_5832

The following sensors have previously been described in other Self-Study Programmes relating to the TDIengine. For this reason, they are not explained in as much detail as the preceding sensors.Air-mass flow meter G70The air-mass flow meter with reverse flow recognitiondetermines the intake air mass. It is located in the intake pipe.The opening and closing actions of the valve produce reverseflows in the induced air mass in the intake pipe.The hot-film air mass meter with reverse flow recognitionrecognises the returning air mass and makes allowance for thisin the signal it sends to the engine control unit. The air mass isthus measured with high accuracy.209_44Signal utilisationThe engine control unit utilises the measured values to calculatethe injection quantity and the exhaust gas recirculation rate.Effects of signal failureIf the signal from the air-mass flow meter fails, the enginecontrol unit uses a fixed substitute value.Coolant temperature sender G62The coolant temperature sender is located at the coolantconnection on the cylinder head. It sends information about thecurrent coolant temperature to the engine control unit.209_60Signal utilisationThe engine control unit uses the coolant temperature as acorrection value for calculating the injection quantity.Effects of signal failureIf the signal fails, the engine control unit uses the signalgenerated by the fuel temperature sender to calculate theinjection quantity.33

Engine management systemAccelerator position sender G79Kick-down switch F8Idling speed switch F60The accelerator position sender is located at the foot controls.The idling speed switch and the kick-down switch are alsointegrated in the sender.209_59Signal utilisationThe engine control unit can recognise the position of theaccelerator pedal from this signal. In vehicles with an automaticgearbox, the kick-down switch indicates to the engine controlunit when the driver wants to accelerate.Effects of signal failureWithout this signal, the engine control unit is unable to recognisethe accelerator pedal position. The engine runs on at a higheridling speed to enable the driver to reach the next workshop.34

Intake manifold pressure sender G71Intake manifold temperature sensor G72The intake manifold pressure sender and the intake manifoldtemperature sensor are integrated in the intake pipe in one unit.209_45Intake manifold pressure sender G71Signal utilisationThe signal which the intake manifold pressure sender supplies isrequired to check the charge pressure. The engine control unitcompares the actual measured value with the setpoint from thecharge pressure map. If the actual value deviates from thesetpoint, then the engine control unit adjusts the charge pressurevia the solenoid valve for charge pressure control.Effects of signal failureThe charge pressure can no longer be regulated. Engineperformance drops.Intake manifold temperature sensor G72Signal utilisationThe engine control unit requires the signal generated by theintake pipe temperature sender as a correction value forcomputing the charge pressure. It can then make allowance forthe effect of temperature on the density of the charge air.Effects of signal failureIf the signal fails, the engine control unit uses a fixed substitutevalue to calculate the charge pressure. This can result in a dropin engine performance.35

Engine management systemAltitude sender F96Altitude senderThe altitude sender is located in the engine control unit.209_61Signal utilisationThe altitude sender sends the momentary ambient air pressureto the engine control unit; this value is dependent on thevehicle's geographical altitude.With this signal the engine control unit can carry out an altitudecorrection for charge pressure control and exhaust gasrecirculation.Effects of signal failureBlack smoke occurs at altitude.Clutch pedal switch F36The clutch pedal switch is located at the foot controls.209_62Signal utilisationThe engine control unit recognises from this signal whether theclutch is engaged or disengaged. When the clutch is engaged,injection quantity is reduced briefly to engine prevent shudderwhen shifting gear.Effects of signal failureIf the signal from the clutch pedal switch fails, power-offreactions can occur when shifting gear.36

Brake light switch F andbrake pedal switch F47The brake light switch and the brake pedal switch are located onthe foot controls in one unit.209_63Signal utilisation:Both switches supply the engine control unit with the “brakeactivated“ signal. For safety reasons, the engine is regulatedwhen the brake is activated, as the electrical acceleratorposition sender could be defective.Effects of signal failure:If one of the two switches fails, the engine control unit reducesthe fuel quantity. Engine performance drops.37

Engine management systemAuxiliary-input signalRoad speed signalThe engine control unitreceives this signal from theroad speed sender.This signal is used tocalculate various functions, the cooling fan run-on and fordamping shudder when shifting gear, as well as forchecking the cruise control system for proper functioning.Air conditioner compressor readyThe air conditioner switch sends engine control unit asignal indicating that the air conditioner compressor willshortly be switched on. This enables the engine controlunit to increase the idling speed of the engine before theair conditioner compressor is switched on to prevent asharp drop in engine speed when the compressor startsup.CCS switchThe signal generated by the CCS switch tells the enginecontrol unit that the cruise control system has beenactivated.3-phase AC alternator terminal DFCAN databusThe signal supplied by terminal DF of the 3-phase ACalternator indicates the load state of the 3-phase ACalternator to the engine control unit. Depending onavailable capacity, the engine control unit can switch onone, two or three glow plugs of the auxiliary heater via therelay for low heater output and the relay for high heateroutput.The engine control unit, the ABS control unit and theautomatic gearbox control unit interchange informationalong a CAN databus.The CAN databus allows large volumes of data to betransferred within a short period of time.For detailed information regarding the CAN databus, please refer toSelf-Study Programme 186.38

ActuatorsInjector solenoid valvesN240, N241, N242, N243The injector solenoid valves are attached to the pump injectorunits by a cap nut.These solenoid valves are activated by the engine control unit.The engine control unit regulates the commencement of injectionpoint and injection quantity of the pump injector units via theinjector solenoid valves.209_64Commencement of injectionpointAs soon as the engine control unit activates an injector solenoidvalve, the magnetic coil presses the solenoid valve needle downinto the valve seat and closes off the path from the fuel supplyline to the high-pressure chamber of the pump injector unit. Theinjection cycle then begins.Injection quantityThe injection quantity is dependent on how long the solenoidvalve is activated. Fuel is injected into the combustion chamberas long as the injector solenoid valve is closed.Effects of failureIf an injector solenoid valve fails, the engine will not run smoothlyand performance will be lower. The injector solenoid valve has adual safety function. If the valve stays open, pressure cannotbuild up in the pump injector. If the valve stays closed, the highpressurechamber of the pump injector can no longer be filled. Inboth cases, no fuel is injected into the cylinders.Electrical circuitJ248N240 N241 N242 N243209_6539

Engine management systemHow the injector solenoid valve is monitoredThe engine control unit monitors the electrical current curve ofthe injector solenoid valve. This information serves the enginecontrol unit as feedback on the actual commencement ofinjection point. The engine control unit can use this feedback toregulate the commencement of injection point and detectmalfunctioning of the valve.This is how it worksThe injection cycle is initiated when the injector solenoid valve isactivated. A magnetic field is built up, the current intensityincreases and the valve closes.A distinct knee appears in the current curve at the point wherethe solenoid valve needle makes contact with the valve seat.This knee point is described as the BIP (abbreviation forBeginning of Injection Period).The BIP indicates to the engine control unit when the injectorsolenoid valve is fully closed, i.e. the point at which injectioncommences.Current curveInjector solenoid valveValveCommencementof activationValve-closingtime= BIPValveEnd of activationCurrent intensityControl limitHolding currentPick-upcurrent209_97Time40

When the valve is closed, the current intensity drops to aconstant holding current. When the desired delivery periodelapses, the activation cycle ends and the valve opens.The engine control unit registers the actual closing time of thepump injector valve, or BIP, for the purpose of calculating theactivation point of the valve for the next injection cycle. If theactual commencement of injection point deviates from the setvalue stored in the engine control unit, the point at whichactivation of the valve begins is corrected.To be able to detect malfunctioning of the valve, the rangewithin which the engine control unit expects the BIP is scannedand evaluated. This range represents the control limit of thecommencement of injection point. When the injector solenoidvalve is functioning properly, the BIP lies within the control limit.If a malfunction occurs, then the BIP will lie outside the controllimit. In this case, the commencement of injection point iscontrolled according to fixed values derived from thecharacteristic curve; the BIP cannot be regulated.ExampleIf there is air inside the pump injector, the solenoid valve needlehas a low resistance when it closes. The valve closes quickly andthe BIP is earlier than expected.In this case, the self-diagnosis indicates the following faultmessage:BIP below control limit41

Engine managementIntake manifold flapchange-over valve N239The intake manifold flap change-over valve islocated in the engine compartment, in the vicinityof the air-mass flow meter. It switches the vacuumfor actuating the intake manifold flap in theintake pipe. This stops the engine shudderingwhen the ignition is turned off.Diesel engines have a high compression ratio.The engine shudders when the ignition is turnedoff on account of the high compression pressureof the induced air.209_68The intake manifold flap interrupts the air supplywhen the engine is turned off. As a result, littleair is compressed and the engine runs softly to ahalt.This is how it worksIf the engine is turned off, the engine-control unitsends a signal to the intake manifold flapchange-over valve. The change-over valve thenswitches the vacuum for the vacuum box. Thevacuum box closes the intake manifold flap.0 I209_69Effects of failureIf the intake manifold flap change-over valvefails, the intake manifold flap stays open.Electrical circuitJ 317SJ248N23942209_70

Fuel cooling relay J445The fuel cooling relay is located in the control unit housing. It isactivated by the engine control unit at a fuel temperature of70°C and switches the working current for the fuel coolingpump.209_71Effects of failureIf the relay drops out, the fuel flowing back from the pumpinjector to the fuel tank will not be cooled. The fuel tank and thefuel level sender can become damaged.Electrical circuitSJ 317A/+SJ248J445V166209_72The actuator diagnosis function in the self-diagnosis can be used to check whether the fuelcooling relay has been activated by the engine control unit.43

Engine management systemThe following actuators have already been described in other Self-Study Programmes dealing with theTDI engine. For this reason, they are not explained in as much detail as the preceding actuators.Solenoid valve forcharge pressure control N75The engine has a variable turbine geometry for adoptingthe charge pressure optimally to the actual drivingconditions. The solenoid valve for charge pressure controlis activated by the engine control unit.The vacuum in the vacuum box for vane adjustment is setdepending on the pulse duty factor. The charge pressure isregulated in this way.209_75Effects of failureAtmospheric pressure is present at the vacuum box. As aresult, the charge pressure is lower and engineperformance is lower.For detailed information regarding the variable turbine geometry, please refer to Self-StudyProgramme 190.EGR valve N18209_73The exhaust gas recirculation system mixes a portion of theexhaust gases with the fresh air supplied to the engine viathe EGR valve. This lowers the combustion temperatureand reduces the formation of nitrogen oxides. The enginecontrol unit activates the exhaust gas recirculation valve.The vacuum for exhaust gas recirculation valve adjustmentis set depending on the pulse duty factor of the signal. Thequantity of exhaust gases returned is controlled in thisway.Effects of failureEngine performance is lower and exhaust gasrecirculation is not assured.44

Warning lamp for glow period K29The warning lamp for glow period is located in the dash panelinsert.It has the following tasks:209_77• It signals to the driver that the pre-startingglow phase is in progress. In this case, it is litcontinuously.•If a component with self-diagnosticcapability becomes faulty, the warning lampflashes.Effects of failure:The warning lamp comes on and does not flash.A fault message is stored to the fault memory.45

Engine managementAuxiliary output signalsCoolant auxiliary heaterThanks to its high efficiency,the engine develops so littlewaste heat that sufficientheat output may not be available in certain circumstances.In countries with cold climates, therefore, an electricalauxiliary heater is used to heat the coolant at lowtemperatures.The auxiliary heater comprises three glow plugs. They areattached to the coolant connection on the cylinder head.The engine control unit utilises this signal to activate therelays for low and high heat output. Therefore, one, two orall three glow plugs for coolant are switched ondepending on the available capacity of the 3-phase ACalternator.Engine speedThis signal serves as information on engine speed for therev counter in the dash panel insert.Cooling fan run-onThe run-on period of the cooling fan is controlledaccording to a characteristic curve stored in the enginecontrol unit. It is calculated from the current coolanttemperature and the load state of the engine during theprevious driving cycle. The engine control unit uses thissignal to activate the relay for radiator fan setting 1.Air conditioner compressor cut-offTo reduce engine load, the engine control unit switches theair conditioner compressor off in the following conditions:• after every starting cycle (for approx. 6 seconds)• under rapid acceleration from the bottom end of the revband• at coolant temperatures in excess of +120°C• in the emergency running programFuel consumption signalThis signal serves as information on fuel consumption forthe multifunctional display in the dash panel insert.46

Glow plug systemGlow plug systemThe glow plug system makes the engine easier tostart at low temperatures. The engine control unitswitches it on when the coolant temperaturedrops below +9°C.The glow plug relay is activated by the enginecontrol unit. The engine control unit then switcheson the working current for the glow plugs.The system overview shows you what sensors usesignals for the glow plug system and whatactuators are activated.System overview of glow plug systemEngine control unit J248Engine speed sender G28Glow plugs Q6Glow plug relay J52Coolant temperaturesender G62Warning lamp forglow period K29The glow process is divided into two phases.209_99Glow phaseAfter he ignition is turned on, the glow plugs areswitched on at a temperature of below +9°C .The warning lamp for glow period comes on.The warning lamp goes out at the end of theglow cycle and the engine can be started.Afterglow phaseThe afterglow phase takes place whenever theengine is started, irrespective of whether it ispreceded by a glow phase or not.This reduces combustion noise, improves idlingquality and reduces hydrocarbon emission.The afterglow phase lasts no more than fourminutes and is interrupted when the enginespeedrises above 2500rpm.47

Engine management systemFunction diagramComponentsE45CCS switch3015SFF8F36Brake light switchKick-down switchClutch switchSSJ 317F47Brake pedal switchA/+F60Idling speed switchSG28G40G62G70G71G72G79G81Engine speed senderHall senderCoolant temperature senderAir-mass flow meterIntake manifold pressure senderIntake manifold temperature sensorAccelerator position senderFuel temperature senderN239 N75 N18J445V166J359Q7J360Q7J52J248Glow plug relayControl unit for diesel direct injection systemJ317J359J360J445Voltage supply relayLow heat output relayHigh heat output relayPump relay, fuel coolingG72N18 EGR valveN75 Solenoid valve for charge pressure controlN239 Intake manifold flap change-over valveN240 No. 1 cylinder unit injector solenoid valveN241 No. 2 cylinder unit injector solenoid valveN242 No. 3 cylinder unit injector solenoid valveN243 No. 4 cylinder unit injector solenoid valveG70G40G71Q6Q7V166Glow plugs (engine)Glow plugs (coolant)Fuel cooling pump31Auxiliary signalsABCDEBrake lightsFuel consumption signalEngine speed signalAir conditioner compressor cut-offAir conditioner compressor readinessFGHKRoad speed signalCCS voltage supplyCooling fan run-onDiagnosis and immobiliser wire48

3015J52SSSSE45A/+B D F GFF47F36CESG62AJ248N240 N241 N242 N243G81F60/F8G79G28NLOMKHinoutQ631209_80LMNOGlow period controlCANbus LowCANbus HighTerminal DFInput signalOutput signalPositiveEarthCAN databus49

Self-diagnosisThe following functions can be read out using theV.A.S. 5051 self-diagnosis, measurement andinformation system:01Interrogate control unit version02Interrogate fault memory03Actuator diagnosis0405Basic adjustmentErase fault memory209_8206End of output07Encode control unit08Read measured value blockFunction 02 Interrogate fault memoryThe colour coded components are stored to thefault memory by the self-diagnosis function.Q6G70G28G40F96J248J52N240, N241,N242, N244K29G79F8F60G62N18N75G71G72FF47N239G81V166J104J217J445209_8150

Engine mechanicalsTo make allowance for the fact that the combustion pressureis higher than in the base engine, the followingmodifications were made to the engine mechanicals:Trapezoidal piston and conrodThe piston hub andthe conrod eye are trapezoidal.209_07Force distribution in a parallelogram-shapedpiston and conrodForce distribution in a trapezoidal piston andconrodCombustion forceContact surfaces209_08 209_09In comparison with the conventional linkbetween the piston and the conrod, the conrodeye and the piston hub have a larger contactsurface area at the piston pin owing to theirtrapezoidal shape.The combustion forces are consequentlydistributed over a large area, and this relievesthe load on the piston pin and conrod.51

Engine mechanicalsThe toothed belt driveHigh pump forces are required to generate aninjection pressure of up to 2000 bar.These forces subject the components of thetoothed belt drive to high loads.For this reason, the following measures weretaken to relieve the load on the toothed belt:• A vibration absorber integrated in thecamshaft gear reduces vibration in thetoothed belt drive.• The toothed belt is 5mm wider than thetoothed belt used in the base engine. Higherforces can be transmitted as it has a largersurface area.• A hydraulic toothed belt tensioner keeps thebelt evenly tensioned in different load states.• Some of the teeth on the crankshaft timing beltgear have a larger gap clearance in order toreduce toothed belt wear.209_89To relieve the load on the toothed belt during theinjection cycle, the toothed belt of the crankshafthas two pairs of teeth which have a larger gapclearance than the other teeth.Gapclearance209_8852

This is how it works:During the injection cycle, the high pumpingforces exert a heavy load on the toothed belt.The camshaft gear is slowed down by thepumping forces. At the same time, thecombustion process which now begins speeds upthe crankshaft timing belt gear. The toothed beltis stretched and the pitch is temporarilyincreased as a result.PitchDeceleration forceOn account of the firing order, this processoccurs periodically. As a result, the same teeth onthe timing belt gear are in mesh every time.The teeth have a larger gap clearance at thesepoints in order to compensate for the change intooth pitch and thus reduce toothed belt wear.Acceleration force209_91On a crankshaft timing belt with a uniform toothgap clearance, the teeth of the toothed belt abutagainst the tooth edges of the timing belt gearwhen the toothed belt is placed under heavystrain by high pumping forces.The upshot of this is that the toothed belt wearsquickly and has a short service life.Deceleration forceAcceleration force209_9253

ServiceSpecial toolsDesignation Tool UseT 10008 marking plateFor fixing the hydraulic toothedbelt tensioner in place wheninstalling and removing thetoothed belt.T 10050 crankshaft stopFor fixing the crankshaft inplace at the crankshaft gearwhen adjusting the port timing.T 10051 counter-holder forcamshaft gearFor installing the camshaft gearT 10052 puller for camshaftgearFor detaching the camshaftgear from the tapered end ofthe camshaftT 10053 assembly fixture forcrankshaft sealing ringGuide sleeve and compressionsleeve for installing thecrankshaft sealing ring54

Special toolsDesignation Tool UseT 10054 socket insertFor fitting the fastening bolt ofthe pump injector clampingblock.T 10055 puller for pumpinjector elementFor pulling the pump injectorout of the cylinder head.T 10056 assembly sleeves forO-ringsFor installing the O-rings of thepump injectors.T 10059 shackleFor installing and removingthe engine in the Passat. Theengine is moved into theinstallation position using thisshackle in combination withlifting gear 2024A.V.A.S. 5187 pressure gaugeFor gauging, the fuel pressureis the supply line to the fuelpump.209_90a-k55

ServiceRepair notesAfter installing the pump injector, the minimumclearance between the base of the high-pressurechamber and the pump piston must be adjustedin the lowest position at the adjusting screw ofthe pump injector.This adjustment prevents the pump pistonknocking against the base of the high-pressurechamber due to heat expansion.Adjusting screwPump pistonMinimum clearanceHigh-pressurechamber209_98You will find a description of the adjustment procedure in the Workshop Manual.56

Test your knowledge1.Identify the components209_232.Which of the following statements is true?a.An engine with a pump injection system is more efficient andcleaner than an engine with a distributor injection pump.b.The high combustion efficiency of the pump injector engine isthe result of the high injection pressure.c.Each cylinder in the engine has a single pump injector.57

Test your knowledge3.What component ends the pre-injection cycle?a.b.c.Injector solenoid valveRetraction pistonInjector needle damper4.What is the task of the fuel cooling system?a.b.It prevents the fuel tank and the fuel level sender from beingdamaged by excessively hot fuel.The cooled fuel lowers the combustion temperature and thusreduces nitrogen oxide emissions.c.Cooling the fuel allows it to be evenly distributed to thecylinders.5.Hall sender G40 . . .a.b.c.. . . determines the engine speed.. . . recognises the individual cylinders.. . . recognises cylinder 1 only6.What makes quick engine starting possible?a.b.During the starting cycle, all injector solenoid valves areactivated simultaneously by the engine control unit.The engine control unit evaluates the signals supplied by theHall sender and engine speed sender. This enables the enginecontrol unit to recognise the position of the crankshaft inrelation to the cylinder at an early stage and activate thecorrect injector solenoid valve to start the injection cycle.c.The injection cycle is started as soon as the engine control unitdetects cylinder 1 through the signal supplied by the Hallsender.58

NotesSolutions:1. For a list of components, refer to page 82. a, b, c3. b4. a5. b6. b

209For internal use only. © VOLKSWAGEN AG, WolfsburgAll rights reserved. Technical specifications subject to change without notice.940.2810.28.20 Technical status: 12/98❀ This paper is produced fromnon-chlorine-bleached pulp.