The ignition system includes spark plugs, high-voltage wires, distributor (aDP engines), electronic ignition coils and an electronic control unit (ECU) with associated sensors, actuators and wiring. The basic operating principle of the system is as follows: voltage is supplied from the ECU to the primary winding of the ignition coil. The incoming voltage is interrupted by the ECU, which causes a change in the magnetic field of the coil, due to which a voltage called high-voltage is induced in the secondary winding (coil-step-up transformer). This voltage is supplied to the spark plugs via high-voltage wires in accordance with the compression stroke. There is a small gap between the spark plug electrodes, in which an electric arc occurs, igniting the fuel-air mixture in the cylinder. The moment of occurrence of a spark between the spark plug electrodes is very critical and is determined by a command from the ECU.
The ECU determines the ignition timing by processing signals from the engine speed sensor, crankshaft position sensor, throttle position sensor, and intake air temperature sensor, which are installed in various places on the engine. The ignition timing is also affected by the coolant temperature and engine detonation, for which the appropriate sensors are provided. On all engines, the initial ignition timing is also determined by signals from the Hall sensor, installed in the distributor (aDP engines) or at the front end of the intake camshaft.
The knock sensor is mounted on the cylinder block, it determines the moment of the beginning of the detonation before it is heard. According to its signals, the ECU delays the ignition, making it later, thus eliminating the onset of detonation combustion and maintaining it on the verge of the beginning of the onset of detonation.
On all engines except those equipped with the Simos system, idle speed control is partly performed by the throttle position module mounted on the throttle body and partly determined by the ignition system, which finely controls idle speed by varying the ignition timing. In the Simos system, the ECU controls idle speed by varying the ignition timing and injection duration. Manual idle speed control is therefore neither necessary nor provided.
It is worth noting that serious troubleshooting of the system is impossible without the use of specialized diagnostic equipment. Therefore, in the event of a malfunction in the system that is not discussed in paragraph 2, it is necessary to seek help from the dealer. When determining the malfunction, the defective unit can be replaced using the detailed information provided in the following paragraphs.
Note: In this chapter, vehicles are identified according to engine model code and engine capacity - a list of engines is given in chapter 2A.