The knock sensor is located in a location that provides optimal knock detection in all engine cylinders. The vibrations of the engine block during detonation are transmitted to the annular piezoceramic disk, where it induces an alternating voltage and outputs it as a signal to the computer via a shielded wire.
In this case, the computer reduces the ignition timing in the corresponding cylinder by 4°. If the detonation in this cylinder does not stop, the ignition timing decreases in all cylinders. The maximum reduction in ignition timing is 12°. After knocking stops, the ECU gradually increases the ignition timing until knocking occurs, and the control cycle is repeated.
When installing two or more sensors, their operation is synchronized with the rotation of the camshafts, which allows you to control the ignition timing for each cylinder separately. Regulation is carried out stepwise, with an interval of 4°.
The use of this sensor allows maintaining the maximum allowable pressure in the combustion chamber of the engine on the verge of detonation combustion. Thus, to ensure the efficient use of fuel with its minimum consumption. The knock sensor detects fluctuations in the combustion process and is directly connected to the ECU-KSUD. In the event of detonation combustion, the UOS is automatically set later.
If the sensor fails, the engine ECU sets the UOZ so late as to exclude detonation combustion, while part of the power is lost, efficiency decreases, but the integrity of the engine is maintained. If one of the knock sensors fails, the ECU automatically sets the ignition timing to the side of delay so that knocking does not occur in the engine.