Control block
It is located in the footwell area of the front passenger in front of the heating duct and receives information from the following nodes via a multi-pin plug:
Hall sensor in the ignition distributor - about the engine speed.
Lambda probe in the catalytic converter - about the content of residual oxygen in the exhaust gases.
Potentiometer - about the position of the throttle valve and the amount of incoming air.
The temperature sensor of the incoming air at the inlet of the combustible mixture preparation unit - about the temperature of the incoming air.
The temperature sensor on the coolant pipe on the left of the cylinder head indicates the temperature of the coolant.
By processing the input signals, the control unit calculates the duration of the opening of the solenoid-driven injection nozzle and thus the amount of fuel to be injected. In this case, the control unit uses the multi-parameter characteristics of the engine - a file in which all possible engine states are recorded. In the same place, information about the quantities of fuel related to a particular situation is recorded in the form of electrical signals. In addition, the ignition timing values relating to the amount of fuel and the operating situation are saved as curves in the Mono-Motronic.
Throttle valve
It is located at the very bottom of the fuel mixture preparation unit and regulates the amount of air that the engine should receive. The degree of opening of the damper is determined by the driver when pressing the accelerator pedal. The pedal and throttle are directly connected to each other by means of an accelerator cable.
Combustible mixture preparation unit
Most of the parts of the central petrol injection system are assembled in this housing. The incoming air passes through it, and here - through the nozzle - fuel is added, as in a carburetor.
Injection nozzle
It opens with an electromagnet. Thus, fuel can flow - or not - depending on the signal from the control unit. For optimal fuel atomization, the nozzle is equipped with beveled outlets through which gasoline enters the conical wall of the outlet, swirling there.
The injection nozzle can only open and close, but is not able to dose the amount of fuel. Therefore, its regulation occurs according to the injection time. This is done as follows: the injector injects once with each high voltage current pulse or Hall sensor. If a small amount of fuel is required, the injector will only open for a short time with this pulse. If the engine needs more fuel, injection occurs for a longer time. And so with each pulse of the Hall sensor.
Functional diagram of the Mono-Motronic injection system. Red shows the fuel in the system, light pink shows the intake air.
Temperature sensor
It is located on the side of the nozzle body and thus can accurately determine the temperature.
Pressure regulator
The pressure fuel pump delivers gasoline to the pressure regulator, which ensures that gasoline flows to the injector at the same pressure of 0.8-1.2 bar. It allows part of the gasoline to go back to the fuel tank through the drain line. The flow through the fuel filter remains almost constant.
Throttle position controller
A small bevel gear motor moves the drive pushrod closer to or further from the throttle stop. Thus, depending on the situation, the throttle valve can be opened more or less. As a result, the idle speed remains constant under different loads. An idle signal switch is located forward in the throttle position actuator actuator to tell the control unit if you release the accelerator pedal.
Throttle Potentiometer
It informs the control unit about the movements of the throttle and its position. So, for example, a quick throttle opening is recognized as vehicle acceleration. If you take your foot off the accelerator pedal, the throttle close signal activates idle fuel cut.
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