Operation of the ignition system (Renault Symbol 1)

The crankshaft position sensor generates signals about the position and speed of rotation of the crankshaft. The electronic control unit, common with the fuel injection system, processes these signals and gives the command to the ignition coils installed on each spark plug to supply a spark according to the principle of dual-spark ignition, i.e. during one engine cycle the spark appears twice - in the compression and exhaust strokes. The ECU, processing signals from various sensors, controls the duration of the ignition pulse and the ignition advance angle, acting as necessary on the primary windings of the ignition coils.

The knock sensor installed on the cylinder block sends a corresponding signal to the ECU based on vibrations and knocks in the cylinders, which delays the control pulse of the ignition unit, reducing the advance until the detonation stops. This creates an optimal moment of fuel combustion, as close as possible to the detonation threshold and ensuring the best engine operation.

In the ignition system used, the ignition timing is determined by the ECU based on a set of engine operating parameters. It is impossible to change the ignition timing independently; diagnostic equipment can only determine whether it is set correctly.