Location of elements of the Simos engine management system. Engines 1.6 l
- 1 connector. For hall sensor (black)
- 2 Hall sensor. Under the top cover of the toothed belt
- 3 oxygen sensor, 50 N. Position at AT: in the exhaust manifold
- 4 socket. For oxygen sensor, on the underside of the car on the right
- 5 inlet manifold switching valve
- 6 Simos control unit
- 7 throttle control unit
- 8 coolant temperature sensor
- 9 air mass meter. With intake air temperature sensor
- 10 ground connection for manual transmission
- 11 ignition coils. With output power level
- 12 socket. For knock sensor
- 13 engine speed sensor
- 14 socket. For engine speed sensor (black)
- 15 knock sensor
- 16 injectors
- 17 fuel pressure regulator
- 18 adsorber
- 19 canister solenoid valve
Location of elements of the Motronic engine management system. Engine 1.8 l (125 HP)
- 1 solenoid valve for canister
- 2 socket. For oxygen sensor (black)
- 3 intake air temperature sensor
- 4 throttle control unit
- 5 control unit Motronic
- 6 camshaft adjustment valve
- 7 air mass meter
- 8 coolant temperature sensor
- 9 fuel pressure regulator
- 10 injectors
- 11 ignition coils, output stage
- 12 engine speed sensor
- 13 knock sensor 2
- 14 connector. For knock sensor 2.
- 15 knock sensor 1
- 16 socket. For the engine speed sensor.
- 17 socket. For knock sensor 1.
- 18 hall sensor
Note: From model 8/97, an adjustable intake pipe with changeover valve is also fitted.
The electronic engine management system regulates the amount of fuel supplied to the cylinders and controls the ignition process. The gasoline engines of the AUDI A3 have different control systems.
The electronic engine management system provides the following features:
- Accurate fuel dosage in any operating mode, which ensures low fuel consumption at high power.
- Reducing the content of harmful substances in exhaust gases due to precise fuel dosing and the use of a catalytic converter.
- Self-diagnosis of the engine management system, which provides the ability to quickly find faults. The engine management system has a fault memory. If a defect is detected during operation, it is stored in the instrument's memory. If there are malfunctions in the engine, then it is possible to print a list of malfunctions to the printer, which allows you to identify and eliminate the defect yourself.
The engine control unit is a microprocessor with high speed. It determines the optimum injection time and the amount of fuel to be injected. In this case, the operation of the control unit is coordinated with other vehicle systems, for example, with the manual transmission control system or the anti-theft lock.
Elements of the engine management system retain their high performance for a long time and require virtually no maintenance. Maintenance replacements require only the air filter and spark plugs. Serious adjustment and repair work requires the use of sophisticated diagnostic tools. Carrying out them is possible only in the conditions of service stations.
Adjustment of the idle speed and CO concentration is not required as part of the maintenance.
Safety Precautions When Working on the Engine Management System/Petrol Engine
The fuel system is under pressure! If the system is opened, fuel may be ejected. Therefore, leaked fuel must be wiped with a cloth. Gasoline vapors are poisonous and flammable. Wear protective goggles. Keep the workplace well ventilated. Have a fire extinguisher ready.
To prevent personal injury and/or damage to the injection and ignition system, the following must be observed:
- Do not touch or disconnect the ignition wires while the engine is running or the starter is engaged.
- Disconnect and connect the pipelines of the injection system and the ignition wires, as well as the electrical wires of the measuring instruments only with the ignition off.
- People with a pacemaker should not work on the electronic ignition system.
- When checking compression, fuel injection is not allowed.
Warning: When working on the injection system, the general rules of safety and cleanliness must be observed.
Notes on checking the engine management system
- For troubleshooting, first of all, it is necessary to read out the indications from the fault memory and check the vacuum connections for tightness.
- For reliable functioning of all electrical elements of the system, a voltage of at least 11.5 V is required.
- If, after troubleshooting, repairing or checking parts, it starts only for a short time and then stops, the cause may be that the anti-theft system is blocked. To do this, it is necessary to interrogate the fault memory and, if necessary, adjust the control unit.
The operation of the gasoline engine injection system
Fuel from the fuel tank is sucked in by an electric fuel pump and fed through a fuel filter located on the floor of the car to the injectors. The pressure regulator maintains a constant pressure in the fuel system.
Through electrically controlled injectors, fuel is metered into the corresponding intake pipe just before the engine intake valves. The engine control unit controls the duration of injection and thus the amount of fuel injected.
The air sucked into the engine passes through the air filter, enters through the throttle valve and the intake pipe to the intake valves.
The intake air mass determines the amount of fuel injected. The mass of intake air is measured by a special meter. In the meter housing there is a thin, electrically heated sensitive plate -1-, which is cooled by the flow of air passing through it. In order to maintain a constant temperature of the sensing plate, the amount of current changes in accordance with the mass of air drawn in. The current value indicates to the control unit the degree of engine load and thereby regulates the amount of fuel injected.
The location of the film conductor 1 in the air mass meter
Information coming from various sensors and commands coming to the executive bodies ensures optimal engine operation in various operating conditions. If the sensors fail, the control unit switches to an emergency program to prevent damage to the engine and allow the vehicle to continue moving. The failure of the sensors does not necessarily have to adversely affect the operation of the engine. However, with a closer control of the composition of the exhaust gases, it is necessary to read the indications of the fault memory of the engine management system.
Engine control sensors and actuators
throttle valve located in the central control unit, where information from various sensors is concentrated. The main task of the control unit is to stabilize the idling mode under all engine operating modes and load conditions. The idle switch sends information to the control unit about the idle position of the throttle valve. The control unit through the electric motor opens or closes the throttle valve, thus regulating the idle speed.
Coolant temperature sensor and intake air temperature sensor transmitting to the control unit information about the current temperature value based on the change in the value of their electrical resistance. As the temperature rises, the resistance decreases.
The fuel tank ventilation system consists of adsorber and solenoid valve. The adsorber accumulates gasoline vapors formed in the tank due to heating of the fuel. When the engine is running, gasoline vapors are sucked out of the adsorber and fed into the engine.
oxygen sensor measures the oxygen content in the exhaust gases and transmits the corresponding signal to the engine control unit.
Knock sensor serves to determine the optimum ignition timing. In the event of ignition failures, the fuel supply to the corresponding cylinder is interrupted.
Engines 1.8 l / 125 hp from 8/97, 1.6L engines have variable intake manifold, which, depending on the engine speed, changes the parameters of the suction tract. To do this, a pneumatically actuated damper is installed in the intake manifold. Due to the resonance effect, the long pipeline at low speeds ensures good filling of the cylinders and thus high torque. At high engine speeds, the intake piping is shortened, which makes better use of the engine's power potential.
Engines 1.8 l/125 hp: To obtain optimum engine power and torque over a wide rev range, there is mechanism for regulating the moment of opening and closing the intake valves depending on the number of revolutions. Typically, the opening and closing times are determined by the camshaft configuration. To allow variable cam adjustment, the intake and exhaust camshafts are connected to each other by a chain. The hydraulic adjustment mechanism, depending on the engine speed, shifts the turning point of the chain in the connection branch of the camshaft gears. Due to this, the phases of the intake valves are shifted in relation to the exhaust valves. To increase torque in the low to mid-range range, an adjustment mechanism is engaged and the intake camshaft opens and closes the valves earlier.
Fuel injection system checks - general information
In the fuel injection system, only the main electrical circuits can be checked independently.
If the normal operation of the engine is disturbed, first check the condition of the electrical wiring and connectors. Check the condition of the air filter element and the condition and gap of the spark plugs. Check the passage of the crankcase ventilation hoses and the adjustment of the accelerator cable. If the engine is still unstable, check the compression in the engine cylinders.
If there is a suspicion of poor performance of the injector, clean it.
If the engine is still erratic, check the ignition system components.
If the problem still persists, check the integrity of the fuses and the condition of the electrical connectors and wiring. The electrical connectors must be free of melted contacts, moisture, corrosion, dirt and other damage.
After carrying out self-test, contact a specialized station "AUDI" for diagnostics of the fuel injection system on special equipment.
Visitor comments