Pic. 1.1, a. Components of the Motronlc system on the AHL engine: 1. Carbon adsorber purge valve; 2. DMRV; 3. coolant temperature sensor; 4. High-voltage output of the ignition coil; 5. Throttle body; 6. Connector for oxygen sensor wiring; 7. Wiring connector for engine speed sensor; 8. Knock sensor wiring connector; 9. BEU; 10. Intake air temperature sensor; 12. Knock sensor; 13. Fuel pressure regulator; 14. Hall sensor wiring; 15. Nozzles; 16. Hall sensor; 17. Oxygen sensor
Pic. 1.1, b. Components of the Motronic system on ADP engines: 1. Ignition coil; 2. coolant temperature sensor; 3. Distributor with Hall sensor; 4. TPS; 5. Wiring connectors for the oxygen sensor, speed sensor and knock sensor; 6. BEU; 7. The solenoid valve of the coal adsorber; 8. DMRV; 9. Oxygen sensor; 10. Nozzles; 11. Knock sensor; 12. Engine speed sensor
Pic. 1.1, c. Components of the Motronic system on ADR engines: 1. Ignition coils and high voltage wires; 2. coolant temperature sensor; 3. TPS; 4. Wiring connectors for the oxygen sensor, speed sensor, knock sensors 1 and 2; 5. BEU; 6. The solenoid valve of the coal adsorber; 7. DMRV; 8. Oxygen sensor; 9. Nozzles; 10. Hall sensor; 11. Knock sensor 1; 12. Knock sensor 2; 13. Engine speed sensor
Pic. 1.1, d. Components of the Motronic system on the AEB engine: 1. Oxygen sensor; 2. coolant temperature sensor; 3. Wiring connectors for the oxygen sensor, engine speed sensor, knock sensors 1 and 2; 4. BEU; 5. The solenoid valve of the coal adsorber; 6. Power ignition; 7. DMRV; 8. Solenoid valve for boost pressure control; 9. Ignition coils; 10. Nozzles; 11. Hall sensor; 12. Knock sensor 1; 13. Knock sensor 2; 14. Engine speed sensor; 15. Intake air temperature sensor; 16. TPS
Pic. 1.1, e. Components of the Motronic system on the APT engine: 1. The solenoid valve of the coal adsorber; 2. DMRV; 3. Ignition coils and high voltage wires; 4. Coolant temperature sensor; 5. Camshaft control valve; 6. Nozzles; 7. Fuel pressure regulator; 8. Knock sensor 2; 9. TPS; 10. Connector for oxygen sensor wiring; 11. Wiring connector for oil sensors; 12. Speed sensor wiring connector; 13. Knock sensor wiring connector 2; 14. Knock sensor wiring connector 1; 15. BEU; 16. Vacuum intake manifold control unit; 17. Intake manifold control valve; 18. Intake air temperature sensor; 19. Engine speed sensor; 20. Knock sensor 1; 21. Hall sensor; 22. Oxygen sensor
General information
The Bosch and Simos multipoint fuel injection systems described in this chapter are systems that control both fuel injection and ignition (pic. 1.1, a-e). This chapter only describes the components of the injection system, the components of the ignition system are described in chapter 5B.
The fuel system consists of a fuel tank (under the back of the car. with built-in electric fuel pump), fuel filter, throttle body, air mass sensor (DMRV), fuel rail with four nozzles, fuel pressure regulator, supply and return pipelines, electronic control unit with sensors and actuators and wiring. The composition of the components depends on the type of system used - see the relevant paragraph.
AEB and AJL engines are equipped with a turbocharger.
The MAF is mounted between the air filter outlet and the throttle body. The fuel pump delivers fuel under pressure to the fuel rail and then to four electronically controlled injectors. The duration of the injection is determined by the ECU, according to the commands from which the nozzles open and close.
The fuel pump delivers fuel through the replaceable fuel filter through the fuel line (fuel supply line) to the fuel rail, the pressure in which is maintained constant by the pressure regulator.
Pressure regulator dumps excess fuel into fuel return line (return fuel line). The constant fuel flow system reduces fuel temperature and prevents vapor lock.
The BEU provides fuel enrichment during start-up and warm-up, idle speed control and exhaust gas composition control. Partial idle is determined by the electronic throttle position module mounted on the side of the throttle body and partly by the ignition system. There is no manual idle adjustment.
Air enters the engine through a replaceable paper air filter.
The oxygen content in the exhaust gases is controlled by the BEU using an oxygen sensor (lambda probe) in the exhaust manifold. The BEU uses the information received from the sensor to control the ratio of the fuel-air mixture. Manual adjustment of the CO content in the exhaust gases is not provided. A catalytic converter is built into the exhaust system of all but the earliest models. An EVAP system is fitted to all models. The coal adsorber is purged by commands from the BEU - the system is described in detail in chapter 4B.
Troubleshooting in the system is possible only with the help of specialized diagnostic equipment. In the event of a malfunction in the system, contact your Audt/VAG dealer for assistance. If a fault is found, the removal and installation of the faulty assembly is described in detail in the following paragraphs.
Note: In this chapter, vehicles are identified according to the engine model code and size - a list of engines is given in chapter 2A.
Precautionary measures
Attention! Many of the procedures in this chapter require the removal of fuel lines and their connections, which can cause fuel spills. Before performing any operation on the fuel system, refer to the warnings given in section "Safety first!" at the beginning of this manual and follow them strictly. Gasoline is a very dangerous volatile liquid and precautions when handling it should not be ignored.
Note. Residual pressure will remain in the fuel lines for a long time after the vehicle has been used. Before disconnecting any fuel line, first depressurize the system as described in paragraph 9.
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