A diesel engine does not need an ignition system, since with a high compression ratio, the intake air is heated so much that after fuel injection, it ignites on its own.
Depending on the year of manufacture and the type of engine in operation, there are different types of ignition systems:
- From January 1984 to August 1988: Ignition system with mechanical interrupter or transistor ignition system.
- From September 1988 to March 1992: Carburetor engines are equipped with a transistor ignition system with mechanical ignition timing adjustment. The 1.5-liter engine with fuel injection is equipped with an electronic ignition system.
- On 16-valve engines, a crankshaft position sensor is installed instead of a distributor. The electronic control unit calculates the ignition timing based on the sensor signals and in accordance with the characteristic embedded in it, and generates a spark using two ignition coils.
In ignition systems with mechanical regulation, a breaker is installed in the ignition distributor, which has the task of inducing ignition voltage in the ignition coil at the moment the primary winding current is interrupted.
The ignition voltage generated in the ignition coil is supplied via the distributor rotor and the ignition wires to the corresponding spark plug. A spark is generated between the spark plug electrodes, which ignites the air-fuel mixture in the combustion chamber of the cylinder. The ignition timing should be automatically shifted in the ignition advance direction as the engine speed increases. This adjustment of the ignition timing occurs in ignition systems with mechanical regulation in the ignition distributor using inertial weights and vacuum (vacuum hose from the intake pipe to the ignition distributor).
In transistor ignition systems, the ignition spark is generated by a signal from a contactless sensor installed in the ignition distributor. The ignition timing is also adjusted using inertial weights and vacuum.
In a 1.5-liter engine with a fuel injection device, the ignition timing is adjusted by a single electronic control unit for the ignition and fuel injection systems. According to the characteristic stored in the unit's memory — see the figure — the control unit sets the optimal ignition timing depending on the engine speed and load. In addition, the computer also controls the ignition process itself. The task of the ignition distributor here is to supply ignition voltage to individual spark plugs in a given sequence.
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16-valve engines have an ignition system without a distributor. The ignition voltage is distributed here by the electronic control unit for the ignition and injection systems. The crankshaft position sensor, driven by the intake camshaft, transmits information about the engine speed and the crankshaft position to the electronic control unit. On engines with a fuel injection device, a knock sensor is installed on the engine block approximately between the 2nd and 3rd cylinders. It registers the occurrence of knock in the engine and notifies the electronic control unit by means of voltage fluctuations about the need to shift the ignition timing in the "late" direction. Shifting the ignition timing prevents knock ignition and thus avoids engine damage.
Caution: When working with the ignition system, safety precautions must be taken.