The injection system and ignition system are controlled by an electronic module. -
The ignition timing is determined by a sensor that is built between the second and third cylinders under the intake manifold on a 4-cylinder engine, or into the cylinder block near the oil filter on a V6 engine. The sensor accurately detects the "sound" or "knock" of the fuel and transmits this pulse to the control unit for processing.
The electronic control unit is installed in the passenger compartment in the tunnel of the center console (models J116/J117) or on the right fender in the engine compartment for other models.
The lambda sensor, which detects the oxygen content in the exhaust gases, is mounted in the front of the exhaust pipe on models with a 4-cylinder engine, or directly in the catalytic converter on models with a V6 engine.
The system also includes an electromagnetic valve for adjusting the idle speed. The valve is installed in the bypass channel.
The injection system consists of three main parts: the fuel system, the electronic module and the sensors that send signals to it, and the electrical supply system. Figure 9.1 shows the engine compartment of a car with a V6 engine.
9.1 Location of individual components in the engine compartment of a car with a V6 engine 1. Electronic module 2. Air filter 3. Absolute pressure sensor 4. Idle speed control valve 5. Fuel lines 6. Throttle body 7. Throttle potentiometer 8. Intake air temperature sensor 9. Throttle cable drive drum 10. Fuel distribution line 11 Fuel pressure regulator 12. Ignition distributor 13. Ignition module 14. Central plug socket for connecting the diagnostic stand
The brain of the system is a single-crystal processor, which also controls the ignition system.
Fuel is supplied by an electric fuel pump, which is mounted on the right-hand side member of the body in front of the fuel tank and covered by a cap. On earlier models, the pump is mounted next to the fuel filter, as shown in Illustration 9.2.
9.2 Position of fuel filter (1) and fuel pump (2) on early models (J116 and J117)
Four or six electromagnetic injectors operate under the control of electrical signals (12 Volts) from the module.
The fuel injection system operates based on signals from various sensors and control factors, some of which are mentioned below. The full load on the engine is determined by the position of the throttle valve at a certain opening angle. The idle position is set as soon as the throttle lever rests against the limiting pin and the idle switch is activated. The Solex throttle body has different diameters depending on the engine type. The thermal switch reacts to changes in engine temperature. The switch is installed in the cooling system and informs the module of the coolant temperature under all operating conditions. The information is sent to the computer, where it is processed in order to make the necessary adjustments. The intake air temperature is measured to provide the engine with the required amount of air, i.e. the air is dosed according to the temperature.
The fuel injection process is complex, i.e. the computer has a microprocessor, a program and a data bank, as well as an analog-to-digital converter. The computer determines the injection time based on the throttle position and engine speed, which are transmitted to it by means of electrical signals from the corresponding sensors. The received signals of various throttle positions and engine speed are recorded and accumulated in a special memory. Whenever these two criteria are in the required ratio, the injection moment is determined, related to the quality of the fuel-air mixture in the cylinders, regardless of the engine load.
How is the quality of the fuel-air mixture regulated? The lambda sensor sends an electrical signal to the module, and the module changes the composition of the fuel-air mixture and at the same time extends or shortens the injection moment. This lambda sensor allows for precise dosing of fuel, thereby helping to establish the CO content in the working mixture within the prescribed limits.
The idle speed is automatically reduced or increased as required by operating conditions. The idle speed control valve sets the throttle valve according to the engine speed for each given moment and the programmed relative value. This relative idle speed is determined by various sensors and determines the throttle angle according to requirements. The idle system does not require any adjustments.