VW Volkswagen 1.9 TDI Industrial engine workshop service manual - NOW

1,9 ltr-TDI-Industrial Engine Technical Status: 4/1999

2 • Combustion process . . . . . . . . . . . . . . . .3 • Injectors . . . . . . . . . . . . . . . . . . . . . . . . .4 • Needle Lift Sender . . . . . . . . . . . . . . . . .5 • Air-mass Flow Meter . . . . . . . . . . . . . . .6 • Modulating piston movement sender . .7 • Installation position . . . . . . . . . . . . . . . .8 • System overview . . . . . . . . . . . . . . . . .10 • Fuel regulation . . . . . . . . . . . . . . . . . . .12 • Injection commencement control . . . . .17 • Exhaust gas recirculation . . . . . . . . . . .22 • Charge pressure control . . . . . . . . . . .24 • Glow plug system . . . . . . . . . . . . . . . .26 • Emission characteristics . . . . . . . . . . . .27 • Internal functions in the control unit . .29 • Self-diagnosis . . . . . . . . . . . . . . . . . . .30 • Performance diagram . . . . . . . . . . . . .31 • Specifications . . . . . . . . . . . . . . . . . . . .32 Detailed instructions regarding testing, adjustment and repair can be found in the Workshop Manual "Volkswagen Industrial Engine". Contents

3 In the direct injection engine, diesel fuel is injected directly into the main combustion chamber. This results in more efficient combustion and lower consumption. The intake port, pistons and injectors have been designed specifically to optimise the combustion process with respect to noise emission and running characteristics. Inlet swirl port The intake port is shaped in such a way that it induces a swirling movement of the intake air and, as a result, produces greater turbulence in the combustion chamber and piston recess. Piston recess The shape of the piston recess has been opti- mised specially for this engine. 5-hole injector The fuel is injected into the piston recess in two stages and is ignited by the hot air. The two-stage injection process avoids a sharp pressure rise. Combustion process

4 Two-spring injector holder To minimise the combustion noise level in the diesel engine and keep mechanical load low, it is necessary for the pressure to rise gently in the combustion chamber. In the case of chamber-type diesel engines, this gentle rise in pressure is achieved, first, by injecting fuel into the pre-chamber or the swirl chamber and, secondly, by using pintle-type injectors. Also, the fuel should be injected gradually, not all at once. A two-spring injector holder has been developed for the 1.9-ltr. direct injection engine. This injector holder, a key factor contributing to the engine’s "soft" combustion characteristic, allows fuel to be injected in two stages. The injector is designed as a five-hole nozzle. Function Two springs with different thicknesses are integrated in the injector holder. The springs have been adapted in such a way that the injector needle is only lifted against the force of the first spring when injection starts. A small quantity of fuel is pre-injected through the small gap which appears at low pressure. This pre-injection cycle produces a gentle rise in the combustion pressure and creates the conditions for igniting the main fuel quantity. As the injection pump delivers more fuel than can actually flow through the small gap, the pressure in the injector rises. The force of the second spring is overcome, and the injector needle is lifted further. The main injection cycle now follows at a higher injection pressure. Injector needle Injector needle Spring 1 Stroke 2 Stroke 1 Stroke 1+2 Spring 2

5 The injector of the 3rd cylinder is equipped with a needle lift sender (G80) for regis- tering the point of commencement of injection. The sender signals the actual opening time of the injector to the control unit. This signal provides the control unit with feedback on whether the point of commencement of fuel injection conforms to the map. Function Needle lift sender G80 is a solenoid and is supplied with a constant current by the control unit. This produces a magnetic field. A pressure pin inside the solenoid forms an extension to the end of the injector needle. The movement of the injector needle alters the magnetic field and causes distortion of the DC voltage applied to the solenoid. The control unit calculates the actual point of commencement of fuel injection from the time difference between the needle lift pulse and the TDC signal supplied by the engine speed sender. At the same time, the system compares the actual point of commencement of injection with the setpoint stored in the control unit and corrects any deviations from the setpoint. Substitute function If the needle lift sender fails, an emergency running program is started. In this program, the commencement of fuel injection is controlled according to fixed setpoints as defined in a map. The injection quantity reduced in addition. Needle Lift Sender Solenoid Pressure pin Injector holder

6 The task of the air-mass flow meter is to measure the fresh air mass supplied to the engine. This fresh air mass is used to calculate the exhaust gas recirculation rate and the permissible injection quantity. Air-mass flow meter Air-mass flow meter Function A heated surface, the hot film, is regulated to a constant temperature. The intake air cools the hot film as it flows past. The current serves as a measure of the intake air mass necessary to keep the temperature of the hot film constant. Substitute function If the air-mass flow meter fails, the control unit defaults a fixed air mass value. This fixed value is calculated such that a reduction in engine performance can only occur in the part-throttle range. Advantages of hot-film air mass metering  Air-mass data can be acquired without additional air pressure and temperature sensors  Reduced flow resistance compared to sensor flap air-flow metering  It is no longer necessary to burn off the hot wire as in the hot wire air-mass flow meter. Hot film

7 Modulating piston movement sender G149 supplies the control unit with information on the momentary position of the quantity adjuster in the injection pump. The injected fuel quantity is calculated from this information. Sender G149 is a non-contact sensor for measuring the angle of rotation. It is attached to the eccentric shaft of the quantity adjuster. Function An alternating magnetic field is produced in a specially shaped iron core by AC voltage. A metal ring attached to the eccentric shaft moves along the iron core and influ- ences this magnetic field. The change in the magnetic field is evaluated electronical- ly in the control unit and indicates the position of the quantity adjuster. Substitute function If the control unit does not receive a signal from the sender for modulating piston movement, the engine is turned off for safety reasons. The new non-contact sender offers the following advantages:  High wear resistance  High interference immunity  Low susceptibility to temperature fluctuation Modulating Piston Movement Sender Iron core Distributor injection pump Fuel temperature sensor G81 Stationary metal ring Eccentric shaft Movable metal ring Coil with AC voltage SSP 153/09

8 Exhaust gas recirculation valve N18 Air-mass flow meter G70 Injector with needle lift sender G80 Distributor injection pump Coolant temperature sender G6 E Intake manifold pressure sender Solenoid valve for charge pressure control N75 EGR valve Hose connection Air-mass flow meter

9 Engine speed sender G28 Intake manifold temperature sensor G72 ontrol unit J248

To optimise engine performance with respect to torque delivery, consumption and emission in every operating situation, the EDC control unit refers to 25 maps and characteristic curves. Sensors supply the control unit with information regarding the vehicle’s momentary operating state. 10 System overview Needle lift sender G80 Engine speed sender G28 Air-mass flow meter G70 Coolant temperature sender G62 Intake manifold temperature sensor G72 Clutch pedal switch F36 Brake switch F Brake pedal switch F47 Modulating piston movement sensor G149 Intake manifold pressure sender Auxiliary signals Diagnostic connector Fuel temperature sender G81 Accelerator position sender G79 EDC control unit J248 Note: The self-diagnosis monitors all the com- ponents above. Sensors

VW Volkswagen 1.9 TDI Industrial engine workshop service manual - NOW

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