New diesel injection technologySP36_01Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted In A. cooperation with Robert Bosch AG, The demands made modern diesel unless on authorised by ŠKODA AUTO A. S. ŠKODA AUTO S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.� Volkswagen has succeeded for the first time engines in respect of power output, fuel in developing a diesel engine with a solenoid consumption, exhaust and noise emissions, valve-controlled unit injection system which is are becoming increasingly greater. Good used in passenger cars. mixture formation is an essential element of satisfying these demands. To accomplish this, engines need efficient fuel This engine satisfies the demands in respect of high power output while at the same time injection systems, which produce high having a minimal impact on the environment. injection pressures for an extremely fine fuel It is a step toward the future of diesel exhaust atomisation, and precisely control the gases which are both free of smoke and commencement of injection and the quantity odours. of fuel injected.A method which satisfies these high demands, is the unit injection system.This new engine generation will also be increasingly used in ŠKODA models.2GBContentsIntroduction Unit Injection System Fuel Supply System Glow Plug System Engine Management System Function Diagram Self-Diagnosis Engine Mechanical Components Test Your Knowledge 4 6 18 25 26 38 41 42 46Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Servicexxxxxxxxxxxxxxxx FABIAServicexxxxxxxxxxxxxxxx FABIAService Service Service Service Servicexxxxxxxxxxxxxxxx FABIA xxxxxxxxxxxxxxxx FABIA xxxxxxxxxxxxxxxx FABIA xxxxxxxxxxxxxxxx FABIA xxxxxxxxxxxxxxxx FABIAS e r v i c eXXXXXXXXXXXXX XXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXX XXXXXXXXYou will find notes on inspection and maintenance, setting and repair instructions in the Workshop Manual.GB3IntroductionThe 1.9-ltr. TDI engine with unit injection systemThe 1.9-ltr. TDI engine with unit injection system is a development based on the 1.9-ltr. TDI engine with distributor injection pump. The primary difference in comparison to this engine is in the nature of the fuel injection. The design and function of this new injection system is presented in this self-study programme and the related new features in terms of the fuel system, the engine management system and the Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted components, are also engine mechanical unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability presented. with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�SP36_05In comparison to the distributor injection pump system, the unit injector stands out by offering the following advantages: – – – – low level of combustion residues low level of pollutant emissions improved fuel consumption high power yieldThese advantages are achieved by: – a high injection pressure of as much as 205 MPa (2050 bar) precise control of the injection process a pre-injection phase– –4GBProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�100020003000 n (1/min)400050006000SP36_28Engine mechanical components – – Turbodiesel engine with charge air cooling. Tandem pump for fuel supply and vacuum supply, electric predelivery pump. Grey cast iron housing. Bucket tappets with hydraulic valve clearance compensation. Each cylinder has a unit injector producing a high injection pressure of 205 MPa (2050 bar). Fuel return flow cooled by air-enveloped cooler at vehicle floor.Technical data Engine code letters: Engine management: Type: Valves per cylinder: Displacement: Bore: Stroke: Compression ratio: Rated output: Max. torque: Emission control: ATD Bosch EDC 15P 4-cyl. in-line engine 2 1896 cm3 79.5 mm 95.5 mm 19.0 : 1 74 kW at 4000 rpm 240 Nm at 1900 ... 2400 rpm Exhaust gas recirculation, oxidation catalytic converter EU3 Diesel, min. CN49 PME, min. CN48– –––Emission standard: Fuel:GB5Unit Injection SystemGeneralWhat is a unit injector? A unit injector is a single-cylinder injection pump controlled by a solenoid valve, and an injection nozzle, which are combined to form a module. In the same way as a distributor injection pump with injectors, the unit injection system performs the following tasks: – producing the high pressure for injecting the fuel, injecting the correct quantity of fuel at the correct moment. Note: The unit injector is also known as UIS (Unit Injector System)–Each cylinder has a unit injector. Consequently, there are only a few parts conveying high pressure.Single-cylinder injection pump (produces pressure)Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability Solenoid with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�valveInjection nozzleSP36_066GBInstallation positionThe unit injector is positioned directly in the cylinder head above each cylinder. O-rings provide a radial seal between the unit injector and the cylinder head.SP36_17Unit injectorCylinder headAttachment/SettingAdjusting boltThe unit injector is attached in the cylinder head with a tensioning clamp. The pump piston is correctly set with the adjusting bolt after being installed.Securing boltunless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�When installing a unit injector, ensure that it is installed in the correct position and properly adjusted. If it is not positioned at right angles to the tensioning block, the bolt holding it may slacken. In such a case, the unit injector or the Protected by copyright. Copying for private or commercial purposes, part orbe in whole, is not permitted cylinder head in may damaged. When correctly set, a minimum clearance exists at the lowest point between the floor of the highpressure chamber and the pump piston (refer also to p. 8). This prevents the pump piston striking the floor of the high-pressure chamber when it heats up.Tensioning clampSP36_18Note: Refer also to the instructions in the Workshop Manual!GB7Unit Injection SystemDesignAdjusting bolt Lock nut Roller rocker armSpherical boltPump pistonPiston springInjection cam Solenoid valve needle High-pressure chamber Unit injector valveFuel return flowRetraction piston Fuel feed O-rings Nozzle springNozzle needle dampingSP36_19Heat protective seal Nozzle needleCylinder head8Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�GBDriveRoller rocker armThe unit injector of each cylinder is operated by a roller rocker arm driven by the camshaft. The camshaft has four additional cams for this purpose, the injection cams, which are positioned between the valve cams. These operate the pump pistons of the unit injectors by means of roller rocker arms.Injection camSP36_20Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability ascending with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Valve camThe injection cam has a steep flank …… and a flat descending flank.The pump piston is pushed down at a high velocity. This in turn very rapidly produces a high injection pressure.As a result of this, the pump piston moves up slowly and evenly and the fuel is able to flow off free of bubbles into the high-pressure chamber of the unit injector.Roller rocker armRoller rocker armInjection camInjection cam Pump pistonSP36_29 SP36_30Pump pistonGB9Unit Injection SystemDemands in respect of mixture formation and combustionGood mixture formation is an essential element of efficient combustion. This necessitates the correct quantity of fuel being injected at the correct moment and at a high pressure. Even minor variations will result in an increase in pollutant emissions, loud combustion noises or a higher fuel consumption. An important element of the combustion process in a diesel engine is a slight ignition lag. The ignition lag is the time between the commencement of injection and the commencement of the pressure rise in the combustion chamber. If a large quantity of fuel is injected during this period, this results in a sudden rise in pressure and thus in loud combustion noises.Pre-injection Before the commencement of the main injection phase a small quantity of fuel is injected at a low pressure – pre-injection – in order to achieve a combustion process which is as smooth as possible. The combustion of this small quantity of fuel in turn produces a rise in pressure and temperature in the combustion chamber.This creates the prerequisite for rapid ignition of the fuel injected during main injection and, in turn, reduces the ignition lag. The pre-injection and an "injection pause" between the pre- and main injection phases ensure that the pressures in the combustion chamber are not produced suddenly, but increase gradually. The consequence of this is a reduction in combustion noises and a lower level of oxide of nitrogen emissions.Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Main injection During the main injection phase the important element is to achieve good mixture formation so that the fuel is combusted to the maximum extent possible. The high injection pressure which is produced results in a very finely atomised fuel which permits the fuel and the air to mix well with each other. Complete combustion results in turn in a reduction in pollutant emissions and in a high power yield.End of injection At the end of the injection cycle it is important that the injection pressure drops rapidly and that the nozzle needle closes quickly. This prevents fuel at a low injection pressure and with a large drop diameter getting into the combustion chamber and combusting in an incomplete manner, which would result in an increase in pollutant emissions.Injection pressureThe injection cycle of the unit injection system with a low pressure during the pre-injection phase, followed by an "injection pause", and then a rise in pressure during main injection, with a rapid end of injection, is closely harmonised to the demands of the engine.Engine demandUnit injectorTime10GBThe injection processThe high-pressure chamber is filled During the filling process, the pump piston is moved up by the force of the piston spring and thus enlarges the volume of the high-pressure chamber. The valve of the unit injector is not operated. The solenoid valve needle is in the unoperated position and opens the passage from the fuel feed to the high-pressure chamber. As a result of the pressure produced by the fuel pump in the feed line, the fuel flows into the highpressure chamber.Roller rocker armPump pistonPiston spring High-pressure chamber Solenoid valve needleUnit injector valveFuel feedProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�SP36_21GB11Unit Injection SystemThe injection processPre-injection commences The pump piston is pushed down by the injection cam acting on the roller rocker arm and, in this way, displaces the fuel out of the high-pressure chamber into the fuel feed. The injection process is initiated by the engine control unit. It operates the unit injector valve for this purpose. When this is done, the solenoid valve needle is pushed into the seat and shuts off the passage from the high-pressure chamber to the fuel feed. As a result, the pressure in the highpressure chamber begins to build up. Once a pressure of 18 MPa (180 bar) is reached, the pretensioning force of the nozzle spring is overcome. The nozzle needle is raised and preinjection commences.Pump piston Solenoid valve seatProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability Solenoid valve needle with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Injection cam High-pressure chamber Unit injector valveFuel feedNozzle needleSP36_2212GBNozzle needle damping During the pre-injection phase, the stroke of the nozzle needle is damped by a hydraulic cushion. this makes it possible to precisely meter the quantity of fuel injected.Process In the first third of the complete stroke the nozzle needle is opened undamped. When this is done, the pre-injection quantity is sprayed into the combustion chamber.Undamped strokeSP36_23Nozzle spring chamberAs soon as the damping piston immerses into the drilling of the nozzle housing, the fuel above the nozzle needle can be displaced into the nozzle spring chamber only through a leak gap. This in turn produces a hydraulic cushion which limits the stroke of the nozzle needle during the preinjection phase.Nozzle housingLeak gapHydraulic cushionProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�SP36_24Damping pistonGB13Unit Injection SystemThe injection processPre-injection ends Pre-injection ends immediately after the nozzle needle opens. As a result of the increasing pressure, the retraction piston moves down and, in this way, enlarges the volume of the highpressure chamber. The pressure drops as a result of this for a short moment and the nozzle needle closes. Pre-injection is thus ended. As a result of the downward movement of the retraction piston, the nozzle spring is pretensioned to a greater extent. A higher fuel pressure than was the case for Pre-injection, is therefore necessary during the subsequent main injection process to once again open the nozzle needle.Pump pistonProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�High-pressure chamber Unit injector valveRetraction pistonNozzle springNozzle needleSP36_2514GBMain injection commencesShortly after the nozzle needle closes, the pressure in the high-pressure chamber again rises. The unit injector valve is still closed during this step and the pump piston moves down. At a pressure of about 30 MPa (300 bar) the force resulting from the fuel pressure is greater than the force of the pretensioned nozzle spring. The nozzle needle is once again raised and the main injection quantity is injected. During this phase, the pressure rises to as much as 205 MPa (2050 bar) because more fuel per unit of time has to be displaced in the highpressure chamber than can escape through the nozzle holes. The pressure is at its highest when the engine is operating at maximum power, in other words at a high engine speed combined with a large quantity of fuel injected.Pump pistonHigh-pressure chamberProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Unit injector valveNozzle springNozzle needleSP36_26GB15Unit Injection SystemThe injection processMain injection ends The end of the main injection phase is initiated once the engine control unit no longer actuates the unit injector valve. When this happens, the solenoid valve needle is opened by the solenoid valve spring. The fuel displaced by the pump piston is now able to escape into the fuel feed. The pressure drops. The nozzle needle closes and the retraction piston is pressed into its initial position by the nozzle spring. Main injection is ended.Pump pistonSolenoid valve springSolenoid valve needleUnit injector valveRetraction pistonFuel feedProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Nozzle needleSP36_1616GBThe fuel return flow in the unit injectorThe fuel return flow in the unit injector performs the following tasks: – Cooling the unit injector. This is achieved by fuel from the fuel feed being flushed through the passages of the unit injector into the fuel return flow. Carrying of the leak fuel at the pump piston.–– Separating vapour bubbles out of the fuel feed through the restrictors in the fuel return flow.Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Pump pistonLeak fuelRestrictorsFuel return flowFuel feedSP36_07GB17Fuel Supply SystemFuel supply systemThere are two pumps which operate for the fuel delivery: – an electric fuel pump* – a mechanical fuel pump. The electric fuel pump operates as a predelivery pump and is positioned in the fuel tank. It pumps fuel at a pressure of 0.05 MPa (0.5 bar) to the mechanical fuel pump. This is flanged to the engine directly next to the vacuum pump at the cylinder head. At ignition "On", the electric pump operates for 2 seconds and switches off again until the engine rotates at starter speed. Then, it runs constantly and, together with the mechanical fuel pump, supplies the fuel directly to the engine. A pressure limiting valve in the electric fuel pump ensures that the fuel pressure at the mechanical pump is approx. 0 MPa (0 bar). The fuel is then pumped by the mechanical fuel pump through the feed drilling in the cylinder head directly to the unit injectors.Preheating valve**, is designed to control the preheating of the fuel.Fuel temperature sensor, determines the temperature of the fuel in the fuel return flow and transmits a signal to the engine control unit.Fuel cooler, with the aid of the ram air, cools the fuel flowing back in order to protect the fuel tank from fuel which is too hot.Electric fuel pump with pressure limiting valve, pumps fuel to the mechanical pumpFuel tankM* Certain models were manufactured at SOP without the electric fuel pump.Fuel filter, protects the fuel injection system from dirt and wear resulting from particles and water.** Depending on the temperature of the fuel in the preheating valve, it directs heated fuel of the return flow line through the fuel filter to the feed line again.Non-return valve, prevents fuel flowing back from the fuel pump into the fuel tank when the engine is not operating [opening pressure = 0.02 MPa (0.2 bar)].18Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�GBFuel not required for injection is pumped back along the return flow drilling in the cylinder head to the fuel tank by the mechanical fuel pump.A temperature sensor and a fuel cooler are integrated in the fuel return-flow line.Bypass If air is present in the fuel system, for example if the fuel tank was run empty, the pressure limiting valve remains closed. The air is forced out of the system by the fuel flowing back.Pressure control valve, limits the pressure in the fuel return flow to 0.1 MPa (1 bar). This ensures that uniform distribution of forces exists at the solenoid valve needle.Restrictor drilling from fuel feed to fuel return flow Vapour bubbles which are present in the fuel feed, are separated out and flow through the restrictor drilling into the fuel return flow.Return flow drilling Feed drillingMechanical fuel pumpCylinder headSP36_04Pressure control valve, controls the fuel pressure in the fuel feed. Valve opens if the fuel pressure rises above 0.75 MPa (7.5 bar). The fuel flows again to the inlet side of the fuel pump.Strainer, traps vapour bubbles in the fuel feed. These then flow along the restrictor drilling and into the return flow.Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�GB19Fuel Supply SystemThe mechanical fuel pumpThe pump is located directly behind the vacuum pump at the side of the cylinder head. Both pumps are driven together by the camshaft. This unit is also known as a tandem pump. The fuel supplied to the engine by the electric pump is pumped by the mechanical one through the fuel feed drilling (in the cylinder head) to the unit injectors.Vacuum pump Fuel pumpA screw plug for connecting a pressure gauge is provided at the fuel pump. This provides a possibility of testing the fuel pressure in the feed.SP36_08Fuel feed drilling (in cylinder head) Fuel return flow drillingProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted (in unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee orcylinder accept any head) liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Pressure control valve for fuel feedLocked vanesThe mechanical fuel pump is a locked vane pump. The locked vanes are pressed against the rotor by the force of a spring. The advantage which this offers is that fuel is pumped already at low rotational speeds. (Vane cell pumps do not pump fuel until the rotational speed is high enough for the vane cells to be pressed against the stator by the centrifugal force.)Fuel feed (from fuel tank)The fuel flow within the pump is designed in drilling in cylinder such a way that the rotor always remains head moistened with fuel even if the tank has run empty. Self-suction is thus assured.RotorFrom return flowSP36_09Restrictor Fuel feed (into cylinder head) Fuel return flow (to fuel tank) Pressure control valve for fuel return flowGB20Function The fuel pump operates according to the principle of: – drawing in fuel as a result of increase in volume – pumping fuel as a result of reduction in volume The fuel is drawn in and pumped in each of two chambers. The inlet chambers and delivery chambers are separated by the locked vanes.Chamber 4Representation of function of chamber 1 and 4 Fuel is drawn in by chamber 1 (suction chamber) and pumped by chamber 4 (delivery chamber). The volume of chamber 1 is enlarged by the rotation of the rotor while the volume of chamber 4 is reduced.SP36_10Chamber 1 RotorChamber 3Representation of function of chamber 2 and 3 In this case, the two other chambers are in action. The fuel is pumped by chamber 2 and drawn in by chamber 3.SP36_11Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Chamber 2GB21Fuel Supply SystemThe fuel railA fuel rail is located in the feed drilling in the cylinder head. Its task is to distribute the fuel evenly to the unit injectors and to ensure even temperature of the fuel which is supplied to the unit injectors.RailSP36_15Cylinder 1Cylinder 2Cylinder 3Cylinder 4 Cylinder headSP36_12Annular gapCross drillingsRailOperating principle The fuel pump supplies the fuel to the fuel rail in the cylinder head. The fuel flows inside the rail in the direction of cylinder 1.Fuel from unit injectorThe fuel is able to flow along cross drillings into the annular gap between the rail and the wall of Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted the cylinder head. The fuel unless is mixed here the A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability authorised by Šwith KODA AUTO respect the correctness of information in this document. Copyright by ŠKODA AUTO A. S.� hot fuel which is pushed backwith into thetofeed drilling by the unit injectors. The result is a uniform temperature of the fuel in the feed at all the cylinders. All the unit injectors are supplied with the same quantity of fuel. This ensures smooth engine running.Cross drillingsMixing of fuel in annular gapFuel to unit injectorSP36_1322GBIn the absence of a fuel rail, the temperature of the fuel at the unit injectors would not be uniform. The hot return flow fuel which is pushed back into the feed drilling by the unit injectors, would be displaced by the inflowing cool feed fuel from cylinder 4 in the direction of cylinder 1.The temperature of the fuel from cylinder 4 to cylinder 1 would rise and the unit injectors would be supplied with different quantities of fuel. The consequences of this would be: – irregular engine running – excessively high temperature at the front cylindersCylinder 1Cylinder 2Cylinder 3Cylinder 4 Cylinder headProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�SP36_14Feed drillingHot return flow fuelCool feed fuelTesting the fuel pressureThe tandem pump is provided specifically with a screw plug for testing the fuel pressure. When this plug is removed, it is possible to connect the pressure measuring device VAS 5187. Test requirements: – – Coolant temperature at least 85 oC Fast idling 1500 rpmVAS 5187The fuel pressure must be at least at the specified pressure of 0.35 MPa (3.5 bar). The rotational speed is determined at the same time as the pressure test is carried out, by means of a fault reader.SP36_67GB23Fuel Supply SystemFuel coolingFuel return flow fuel tank (cooled)Fuel feed to engineFuel cooler with cooling ribsFuel return flow from engine (hot)SP36_27As a result of the high pressure in the unit injectors, the fuel is heated to such an extent that it must be cooled down before it flows back into the fuel tank. That is why a fuel cooler is integrated additionally in the fuel return-flow line. The fuel flowing back from the unit injectors through the fuel pump flows through the fuel cooler, which is provided with cooling ribs, and which absorb the heat of the fuel. The air flow at this point (ram air) additionally extracts heat from the hot fuel.The cooled fuel flowing back now does not have any negative effects on the fuel tank, on the electric fuel pump and on the fuel gauge sensor. The fuel cooler is positioned on the left at the underfloor of the vehicle in the return-flow line to the fuel tank. The fuel lines can easily be detached from the fuel tank, if required (quick-locks).Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�24GBGlow Plug SystemGlow plug systemStarting the engine is facilitated at low temperatures by means of the preglow system. It is switched on by the engine control unit if the coolant temperature is less than +9 ˚C. The glow plug relay is actuated in this case by the engine control unit. It, in turn, switches on the operating current for the glow plugs. The system overview shows which sensor signals are used for the glow plug system and which actuators are operated. The glow period warning lamp is operated over the drive CAN databus by the engine control unit to the control unit in the dash panel insert.System overview of glow plug systemEngine control unit J248Engine speed sender G28Glow plugs Q6Glow plug relay J52 Coolant temperature sender G62Glow period warning lamp K29SP36_35Preglowing When the ignition is switched on, the glow plugs are operated if the coolant temperature is below +9 ˚C. The glow period warning lamp comes on. Once the glowing operation is ended, the warning lamp goes out and the engine can be started.Afterglowing Afterglowing is activated each time the engine is started, irrespective of whether preglowing was actuated. The aim of this is to reduce combustion noises, improve the idling quality of the engine and reduce the hydrocarbon emissions. The afterglowing phase lasts up to four minutes and is interrupted once engine speed rises above 2500 rpm.Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�GB25Engine Management SystemSystem overviewAir mass meter G70 Altitude sender F96Engine speed sender G28Camshaft position sensorAccelerator pedal position sender G79 Kickdown switch F8 Idling speed switch F60 Drive CAN K wire Vehicle electrical system control unit J519Coolant temperature sender G62 Intake manifold pressure sender G71 Intake manifold temperature sender G72 Clutch pedal switch F36 Brake light switch F Brake pedal switch F47 Fuel temperature sender G81Additional signals: Vehicle speed signal CCS switch (ON/OFF) Alternator terminal DFM PTC heater on26Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted GBliability unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Fuel pump relay J17 Fuel pump G6*Diesel direct injection system control unit J248Glow plug relay J52 Glow plugs Q6Unit injectors, cylinders 1 - 4 N240 … N243Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�EGR valve N18Charge pressure control solenoid valve N75Intake manifold flap changeover valve N239 Glow period warning lamp K29 Low heating capacity relay J359 High heating capacity relay J360 PTC heater Additional signals: Radiator fan engine-off runningSP36_34* Note: Certain models were manufactured at SOP without the electric fuel pump G6.GB27Engine Management SystemCamshaft position sensor G40Camshaft sensor gearThe camshaft position sensor operates according to the Hall sensor principle. The sensor is attached to the toothed belt guard below the camshaft sprocket. It scans the teeth on the sensor gear of the camshaft (7 teeth differently positioned).SP36_53Camshaft position sensorUse of signalThe signal supplied by camshaft position sensor is used by the engine control unit at engine start to detect the cylinders.Effect in the event of signal failureIf no signal is received, the control unit uses the signal supplied by the engine speed sender G28.Electric circuitProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�30/+J322+G40o-18 J248109101SP36_5228GBCylinder recognition at engine start When the engine is started, the engine control unit must recognise which cylinder is in the compression stroke in order to operate the matching unit injector valve. It does this by analysing the signal supplied by the camshaft position sensor, which scans the teeth of the sensor gear of the camshaft and, in this way, determines the position of the camshaft.The sensor gear of the camshaft Since the camshaft makes a rotation of 360˚ during each working cycle, there is a tooth for each cylinder spaced every 90˚ on the sensor gear. To enable the teeth to be matched to the appropriate cylinders, the sensor gear has an additional tooth each for cylinders 1, 2 and 3, each of which is differently spaced.SP36_54This is how itProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.� operates:Each time that a tooth moves past the camshaft position sensor, a Hall voltage is produced, which is transmitted to the engine control unit. Because of the different spacing of the teeth, the Hall voltages occur at different time spacings.The engine control unit analyses the signals and is able to recognise the relevant cylinder and operate the correct unit injector valve.Signal pattern of Hall sender90o90o90o90oCylinder 1Cylinder 3Cylinder 4Cylinder 2Cylinder 1SP36_55GB29Engine Management SystemEngine speed sender G28The engine speed sender is an inductive sensor. It is attached to the cylinder block at the flywheel side.SP36_46Engine speed sensor gearThe engine speed sender scans a sensor gear which is attached to the crankshaft. The sensor gear has 56 teeth around its circumference, with 2 gaps each of 2 missing teeth. The gaps are offset 180˚ and act as reference marks for determining the position of the crankshaft.SP36_46Use of signalThe signal supplied by the engine speed sender makes it possible to determine the speed of the engine and the exact position of the crankshaft. This information is used to calculate the moment of injection and the quantity of fuel injected. If no signal is received from the engine speed sender, the engine stops and cannot be started again.Effect in the event of signal failureProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability withcircuit respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.� ElectricJ248 110 102G28SP36_4830GBFunction of quick-start recognitionWhen the engine is started, the engine control unit instantaneously analyses the signal supplied by the camshaft position sensor and by the engine speed sender. It recognises the cylinders from the signal supplied by camshaft position sensor, which scans the sensor gear of the camshaft. As a result of the 2 gaps on the sensor gear of the crankshaft, the engine control unit receives a reference signal as quickly as the first half revolution of the crankshaft. Consequently, the engine control unit recognises the position of the crankshaft at a very early stage, and is able to operate the correct solenoid valve in order to initiate the fuel injection process.Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Signal pattern of camshaft position sensor and engine speed sender1 camshaft revolution Cylinder 1 Cylinder 3 Cylinder 4 Cylinder 2 Signal from camshaft position sensor1 crankshaft revolutionSignal from engine speed senderSP36_49GB31Engine Management SystemFuel temperature sender G81The sender is located in the fuel return-flow line downstream of the fuel pump. What it determines is the current fuel temperature. The sender is a temperature sensor with a negative temperature coefficient (NTC). The resistance of the sensor reduces as the fuel temperature rises.SP36_36Use of signalThe signal is used for detecting the fuel temperature. The engine control unit requires this information for calculating the commencement of delivery and the quantity injected in order to allow for the density of the fuel at differing temperatures.Effect in the event of signal failureIf no signal is received, the engine control unit calculates a substitute value from the signal supplied by the coolant temperature sender G62.Electric circuitProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability J248 with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�111103G81SP36_3732GBUnit injector valve N240, N241, N242, N243Each unit injector features a valve which is attached directly to it. The valves are electromagnetically operated valves, which are actuated by the engine control unit. The commencement of delivery and the quantity of fuel injected are controlled by the engine control unit through these valves.SP36_33Commencement of deliveryWhen the valve is operated, the solenoid valve needle is pressed into the seat. The passage from the fuel feed to the high-pressure chamber of the unit injector is closed off. Fuel injection then commences.Injected quantityThe quantity of fuel injected is determined by the actuation period. Once the valve is closed, fuel is injected into the combustion chamber.Effect in the event of failureIf a valve fails, engine running becomes irregular and output is reduced. The unit injector valve has a double safety function: – If the valve remains open, it is not possible for pressure to be built up in the unit injector. – If the valve remains closed, it is not possible for the high-pressure chamber of the unit injector to be filled. No fuel is injected into the cylinder in both cases.Electric circuit J248 N240 … N243Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�J248Diesel direct injection system control unit Unit injector valve for cylinders 1 … 4N240N241N242N243SP36_03GB33Engine Management SystemMonitoring unit injector valveThe engine control unit monitors the current flow of the unit injector valve. In order to control the commencement of delivery, it is supplied with a feedback on the actual commencement of delivery. It is possible to detect operating faults in the valve.ProcessThe injection process is commenced when the unit injector valve is operated. When this is done, a magnetic field is produced, the amperage rises and the valve closes. When the solenoid valve needle strikes the seat, of the This droop is known as BIP (abbreviation for Beginning of Injection Period). The BIP signals to the engine control unit that the unit injector valve is fully closed and thus the moment of commencement of injection.there is a pronounced droop the pattern Protected by copyright. Copying for private or commercial purposes, in part or in whole,in is not permitted unless authorised by ŠKODA AUTO A. S.current. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Pattern of current of unit injector valveStart of valve actuation BIPEnd of valve actuationAmperageHolding current Control limitStarting currentTimeSP36_5034GBIf the valve is closed, the amperage drops to a constant holding current. Once the desired delivery period is reached, actuation is ended and the valve opens. The actual moment at which the valve closes is detected by the engine control unit in order to calculate the moment of actuation of the valve for the next injection cycle. If the actual beginning of delivery differs from the set values stored in the engine control unit, the commencement of actuation of the valve is adjusted. The range in which the engine control unit expects the BIP is scanned and analysed in order to be able to detect any operating problems of the valve. This range designates the control limit of the beginning of injection. If the valve operates properly, the BIP appears within the control limit. If an operating problem exists, the BIP appears beyond the control limit. In this case, the beginning of delivery is controlled in line with fixed values from the map; a closed-loop control is not possible.Example of operational problemIf air is present in the unit injector, the solenoid valve needle has a slight resistance when closing. The valve closes more rapidly and the BIP appears at an earlier moment than expected.In such a case, the following fault message appears in the self-diagnosis:Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness ofControl information in this document. Copyright by ŠKODA AUTO A. S.� limit not reachedGB35Engine Management SystemNote: Function components which are also fitted to the 1.9-ltr. TDI 81 kW and 50 kW engine, and also to petrol engines, are likewise used in the1.9-ltr. engine for controlling the unit injection system. Please also refer to the existing selfstudy programmes for further information on these.Function componentFunction descriptionAir mass meter G70 It determines the inducted air mass in the intake manifold.SP36_38SSP 16 SSP 23Coolant temperature sender G62Protected by copyright. Copying for private commercial purposes,unit in parton or incurrent whole, is not permitted Supplies information toorengine control unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability coolant temperature. with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�SSP 16SP36_39Accelerator pedal position sender G79, F8, F60 Supplies information (electrically) on current accelerator pedal position to engine control unit.SP27_27SSP 16 SSP 27Intake manifold pressure sender G71 and temperature sender G72 Signals used for limiting charge pressure.SP36_40SSP 16Altitude sender F96 Signal used by engine control unit for altitude correction of charge pressure control.SP16_04SSP 1636GBFunction componentFunction descriptionClutch pedal switch F36 Influences the injected quantity control during gear change (smooth running).SP36_41SSP 16Brake pedal switch F and F47 Operates brake lights and signals "brake operated" to control unit.SP36_42SSP 16Exhaust gas recirculation Portions of exhaust gases are mixed with the inducted air. The pollutant level in exhaust is reduced.SP36_58SSP 16SP36_45EGR valve N18 Controls the quantity of exhaust gas supplied to the fresh air.SSP 16 SSP 22Turbocharger with variable guide vanes. Precompressed air is forced into the cylinder.SP36_59SSP 16 SSP 22SP27_44Charge pressure control solenoid valve N75 Limits charge pressure in line with charge pressure map.SSP 16 SSP 22Intake manifold flap N239 Prevents bucking movements when engine switched off by closing the intake manifold.SP36_43SSP 22Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�GB37Function Diagram+30 +15SSSSSJ322S CAN - H 37 CAN - LG70 G40N79N239N75N18+ Ko-+AProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�-458162614683010910116671852733171110 102517063 69501238 46 152911G72A BG71 G28 F60/F8 G79C DE3138Legend of function diagram page 40GBJ519+30 +15SJ52 S S SJ17FF47F36J359J360Q642 J248 112 104 11112326566212210380 114 116 117Copying 118 121 Protected by copyright. for private or commercial purposes, in part or in whole, is not permittedunless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by S ŠKODA S AUTO A. S SS.�N240N241N242N243 PTCM4 G6G62G8131inoutSP36_56GB39Function DiagramLegend of function diagramComponents A F F8 F36 F47 F60 G6 G28 G40 G62 G70 G71 G72 G79 G81 J17 J52 J248 J322 J359 J360 J519 N18 N75 N79 N239 N240 N241 N242 N243 Q6 S Battery Brake light switch Kickdown switch Clutch pedal switch Brake pedal switch for CCS/diesel direct injection system Idling speed switch Fuel pump (predelivery pump)* Engine speed sender Camshaft position sensor Coolant temperature sender Air mass meter Intake manifold pressure sender Intake manifold temperature sender Accelerator pedal position sender Fuel temperature sender Fuel pump relay Glow plug relay Diesel direct injection system control unit Diesel direct injection system relay Low heating capacity relay High heating capacity relay Vehicle electrical system control unit EGR valve Charge pressure control solenoid valve Heating resistor (crankcase ventilation) Intake manifold flap changeover valve Unit injector valve, cylinder 1 Unit injector valve, cylinder 2 Unit injector valve, cylinder 3 Unit injector valve, cylinder 4 Glow plugs (engine) FusesAdditional signals A B C D E Alternator DFM CCS switch On/Off PTC heater on Vehicle speed signal Radiator fan engine-off runningColour coding = Input signal = Output signal = Battery positive = Earth = CAN databus = Diagnostic connectionunless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�* Note: Certain models were manufactured Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted at SOP without a predelivery pump.The function diagram represents a simplified current flow diagram. It shows all the linkages of the Bosch EPC 15 P engine management system.40GBSelf-DiagnosisThe control unit for the diesel direct injection system is equipped with a fault memory. Address word: 01 – Engine electronics The following functions can be read with the vehicle diagnosis, test and information system VAS 5051, or with the vehicle system tester V.A.G 1552: 01 - Interrogating control unit version 02 - Interrogating fault memory 03 - Final control diagnosis 04 - Basic setting 05 - Erasing fault memory 06 - Ending output 07 - Coding control unit 08 - Reading measured value block Any faults which exist at all the colour-coded components, are output in function 02 – Interrogating fault memory.SP33_73Note: The engine should be idling for this step.Legend of components ⇒ Function Diagram.G 70 J 248G6G 28 G 40J 52 N 240 N 241 N 242 N 243 N 18G 79G 62 G 71 G 72 F F 47Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted N 75 unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�N 239 K 29 J 519 J 359 J 360G 81SP36_57GB41Engine Mechanical ComponentsHigher combustion pressures occur in the unit injection system than in a conventional diesel engine. The geometry of the piston and connecting rod have been modified to take account of this situation:Trapezoidal piston and trapezoidal conrodThe piston hub and the conrod eye are trapezoidal in shape. In comparison to the conventional connection between piston and conrod, the contact surface of the conrod eye and piston hub is enlarged at the piston pin as a result of the trapezoidal shape.Trapezoidal shape at piston hubTrapezoidal shape at conrodDistributing the combustion forces over a greater Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted surface area results in a reduced load acting on unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.� the piston pin and conrod.SP36_65Combustion forcesCombustion forcesContact surfacexxxxSP36_63Enlarged surfaceSP36_64Distribution of forces in a piston and conrod of parallel shapeDistribution of forces in a piston and conrod of trapezoidal shape42GBPiston coolingAs you are aware, a small part of the lubricating oil is branched off from the oil circuit for cooling the piston and sprayed directly into the interior of the piston. An oil spray nozzle, which is supplied with oil directly from the oil pump along an oil gallery, is positioned in the area below each piston at the cylinder.Ring-shaped cooling passageThe piston is now provided additionally with a ring-shaped cooling passage in the ring area of the piston and at the edge of the recess for reducing the temperature at these areas. Cooling oil is now no longer sprayed onto the inner wall of the piston, but the spray nozzle immerses into the funnel-shaped enlargement of the feed drilling at bottom dead centre. The oil is forced into a small circumferential passage and drips off down again out of the piston. The spray oil which flows through the cooling passage, cools out the piston from the inside.Oil spray nozzleSP36_66Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�GB43Engine Mechanical ComponentsThe toothed belt driveLarge pump forces are required for producing an injection pressure of as much as 205 MPa (2050 bar). These subject the components of the toothed belt drive to very severe stresses. A number of design measures have been implemented in order to relieve the stress on the toothed belt: – A vibration damper, which reduces vibrations in the toothed belt drive, is located in the camshaft sprocket. The toothed belt has been widened by 5 mm to enable higher forces to be transmitted. A tensioning device for the toothed belt ensures that the belt is always uniformly tensioned even in different load situations. The crankshaft toothed belt sprocket has 2 enlarged pairs of teeth gaps in order to minimise the wear of the toothed belt.SP36_51Camshaft sprocketTensioning pulleyTensioning device Coolant pump–Guide pulley–Crankshaft toothed belt sprocket–When the high injection pressures are produced, the stretch of the toothed belt resulting from the high loads which occur, is minimal. The stresses to which the toothed belt is subjected during the fuel injection process are minimised by 2 successive tooth gaps positioned at 2 points around the circumference of the crankshaft toothed belt sprocket with a spacing of 180˚, these tooth gaps being larger in size than the other gaps.aConsequently, the teeth of the stretched toothed belt mesh into the larger tooth gap and do not strike a tooth of the crankshaft toothed belt Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted sprocket. unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liabilitywith respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�bSP36_50a - normal gap width b - enlarged gap width44GBProcess During fuel injection, the toothed belt is subjected to severe stresses as a result of the high pump forces. The camshaft sprocket is decelerated by the pump forces, while at the same time the combustion process which has been initiated, accelerates the toothed sprocket of the crankshaft. This results in a stretching of the toothed belt and the tooth spacing becomes larger during this time.Deceleration forcespa cin To oth gBecause of the firing order, this process occurs periodically so that the same teeth at the toothed belt are meshed each time. The crankshaft toothed belt sprocket has enlarged tooth gaps at these points and thus also a greater play between toothed belt and the toothed sprocket of the crankshaft. This compensates for any variation in the tooth spacing and reduces the wear of the toothed belt.SP36_61Acceleration forceDeceleration forceIf the crankshaft sprocket of the toothed belt had uniform tooth gaps, the teeth of the belt would Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted strike the edges of the teeth of the crankshaft unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability toothed belt sprocket when the belt is subjected with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.� to the high pump forces. The consequence would be high wear and reduced life of the toothed belt.Acceleration forceSP36_62GB45Test Your KnowledgeWhich answers are correct? Sometimes only one. But, perhaps also more than one – or all!1.An engine with a unit injection system A. B. C.has a unit injector at each cylinder, operates with a high injection pressure, which results in good combustion, has a higher power yield and reduced pollutant emission levels compared to an engine with a distributor injection pump.2.Each unit injector features a valve, A. B. C.his is an electro-magnetically operated valve and is actuated by the engine control uni, which is opened for the main injection phase, which is closed for the main injection phase.authorised by ŠKODA AUTO S. ŠKODA A. S. does 3.unlessThe pump piston inA. the unit AUTO injector is not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permittedA. B. C.operated directly by the pump cam, operated by the camshaft by means of roller rocker arms, controlled by the solenoid valve.4.The fuel is pumped from the fuel tank to the engine by A. B. C.the pump piston, an electric fuel pump, an electric predelivery pump and a mechanical fuel pump.?SP36_6846GB5.Pre-injection is ended by A. B. C.the unit injector valve, the retraction piston, the nozzle needle damping.6.What is the task of the fuel cooling system? A. B. C.It prevents the fuel tank, the electric fuel pump and the fuel gauge sender being damaged by fuel which is too hot. Reducing the combustion temperature as a result of cooled fuel. The fuel cooling system ensures that the fuel is distributed uniformly in the rail to the cylinders.7.The camshaft position sensor G40 … A. B. C.… determines the engine speed, … is used for recognising the individual cylinders, … is used only for recognising cylinder 1.8.If no signal is received from the A. B. C.engine speed sender G28 camshaft position sensor G40 fuel temperature sender G81the engine stops and cannot be started again.Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not permitted unless authorised by ŠKODA AUTO A. S. ŠKODA AUTO A. S. does not guarantee or accept any liability with respect to the correctness of information in this document. Copyright by ŠKODA AUTO A. S.�GBAnswers 1. A, B, C; 2. A, C; 3. B; 4. C; 5. B; 6. A; 7. B; 8. A47?