Vehicles with 1.4 liter engine
The Mono-Motronic system is an electronic fuel injection system for gasoline engines. Fuel is injected intermittently into the header pipe. Unlike other injection systems, Mono-Motronic has only one injector common to all cylinders. Thus, this system is one-point (single injection). Further distribution and supply of fuel to the combustion chambers of the cylinders is carried out from the manifold. The principle of operation in this case resembles the injection performed by a carburetor.
The required amount of air is taken in by the engine through the air filter and fed to the throttle valve, which is controlled by a cable from the accelerator pedal. As a value that determines the amount of intake air, is the vacuum in the intake manifold and the number of engine revolutions at the current moment. The intake manifold pressure sensor is located on the dividing wall of the engine compartment. It is connected to the intake manifold with a hose. In the event of a sensor failure, the intake manifold pressure is determined by the engine control unit from the throttle valve opening angle and the engine speed. The engine speed is read by an inductive encoder on the flywheel. Sensor signals are also needed for the ignition system (see illustration 1.0).
1.0 Operation of the Mono-Jetronic system: 1 - coolant temperature indicator sensor; 2 - detonation combustion sensor; 3 - pulse sensor of engine speed / TDC; 4 - nozzle; 5 - intake air temperature sensor; 6 - throttle position potentiometer; 7 - executive electric motor of the engine idle speed controller; 8 - throttle body; 9 - pressure sensor in the intake manifold; 10 - control unit (microprocessor); 11 - ignition coil; 12 - ventilation valve; 13 - solenoid valve; 14 - adsorber filter; 15 - fuel filter; 16 - fuel tank; 17 - fuel pump in the fuel tank; 18 - oxygen sensor (Lambda probe); 19 - return valve; 20 - catalyst
The microprocessor, in accordance with the data on the volume of air and the number of revolutions of the engine at the current moment, determines the necessary time for fuel injection and the volume of injected fuel. The longer the injector stays open, the more fuel is injected. To keep the injected volume at a constant level, a fuel pressure regulator is installed on the injection unit. This regulator keeps the fuel pressure within 1 bar of the air pressure in the intake manifold. Additional sensors provide the supply of the required amount of fuel in accordance with the load on the engine at the current moment of movement.
The idle speed sensor sends throttle valve angle data to the engine control unit.
The control unit opens or closes the throttle valve via the governor actuator and thus brings the engine idle speed to the nominal value.
The engine temperature is recorded by the coolant temperature gauge sensor.
The intake air temperature sensor on the fuel injector senses the intake air temperature.
Lambda probe (oxygen sensor), as well as the adsorber, are the same in design as those of the multipoint injection system.