Fuel injection system
Fuel injection system of the engine OHC
1 – intake manifold; 2 – connecting the brake booster hose; 3 – coolant temperature sensor; 4 – fuel line; 5 – pressure regulator; 6 – throttle body; 7; 12 – gaskets; 8 – sealing rings; 9 – fuel injector; 10 – fuel distribution line; 11 – throttle position potentiometer; 13 – idle speed controller
Fuel injection system of the DOHC engine
1 – intake manifold; 2 – throttle body; 3 – idle speed controller; 4 – coolant temperature sensor; 5 – pressure regulator; 6 – fuel temperature sensor; 7 – fuel distribution line; 8 – sealing rings; 9 – fuel injector
Fuel injection system relay for V6 2.4 and 2.9 dm³ engines
The relays are located under the instrument panel on the passenger side.
1 – power relay, 2 – fuel pump relay
The cars can be equipped with Bosch K-Jetronic or Bosch L-Jetronic fuel injection systems. Control is performed by the EEC IV module (Electronic Engine Control MK IV), which also controls the ignition system.
Fuel under pressure developed by the fuel pump is supplied through the pressure accumulator and fuel filter. Air flow is regulated by the throttle valve depending on the position of the accelerator pedal. The amount of air entering the engine cylinders through the flow meter is the main value controlling the mixture formation process.
Fuel injectors receive electrical pulses: one pulse per revolution of the crankshaft. Fuel injectors of the DOHC engine are triggered in pairs by pulses from the EEC IV module and fuel is injected by a pair of injectors for every half revolution of the crankshaft. The pulse duration depends on the amount of fuel being injected. The pulse duration is calculated by the EEC IV module based on information from various sensors. One fuel injector is installed in each cylinder.
The air sucked in by the engine passes through the air flow meter. On V6 engines, two air flow meters are installed. The air flow meter plate in the meter deflects proportionally to the flow rate: this deflection is converted into an electrical signal for the EEC IV module. An adjustable bypass channel ensures engine idling.
The throttle position sensor informs the EECIV module of the throttle position and the rate of change of the throttle position, so that additional fuel is supplied when the throttle is opened sharply to accelerate the vehicle. To save fuel, there is a system for shutting off the fuel supply in the engine braking mode.
Idle speed is controlled by a thermoelectric valve in the jet, which regulates the amount of air bypassing the throttle valve via an additional channel. The valve is controlled by the EEC IV module. Direct adjustment of idle speed is not provided.
Sensors located on the engine ensure precise fuel dosing in all engine operating modes at any ambient temperatures. On models with an automatic transmission, the sensor registers the position of the gearbox shifter from P – parking or N – neutral, to D – forward movement, causing a corresponding change in idle speed. Additional DOHC engine sensors report data on fuel temperature, coolant temperature, vehicle speed to the EEC IV module (the sensor is located in the gearbox).
If an air conditioner is present, the signal from the compressor allows the idle speed to be set independently of the load created by the air conditioner compressor.
On DOHC models without a catalytic converter, idle mixture adjustment is performed by a potentiometer directly connected to the EEC IV module. On DOHC models with a converter, the exhaust oxygen sensor allows the EEC IV module to control the air/fuel mixture so that it matches the operating parameters. Therefore, manual mixture adjustment is not possible.
On DOHC catalytic converter models, a fuel evaporation control system is installed. The system prevents gasoline vapors from escaping into the atmosphere. When the ignition is off, vapors from the fuel tank enter the carbon canister. When the engine is running, the EEC IV module opens the electromagnetic valve and they enter the intake manifold and mix with fresh air. This cleans the carbon canister. A special valve prevents the intake air from entering the fuel tank.
The EEC IV module has a "limited mode" (LOS) that allows the vehicle to be driven, albeit with a loss of power, in the event of a module or fuel injection system sensor failure.
Since mid-1986, all models have been equipped with an inertia switch for the fuel pump. The switch interrupts the electrical circuit of the pump in the event of an accident or strong impact. The switch is located to the left of the trunk lid lock under a plastic cap. It is switched on by pressing the button on the top of the switch.