Knock sensor. Detonation adjustment

Knocking combustion occurs due to too early ignition timing. Prolonged detonation can cause severe damage to internal engine parts. However, in modern automotive industry, they constantly try to bring the ignition timing as close as possible to «early ignition». The ignition system provides detonation damping by adjusting the ignition timing. It allows you to use the maximum ignition timing in the absence of detonation, thus ensuring good driving performance and low fuel consumption. The system has an electrical knock sensor to detect knocking (one for the 2.0-liter engine or two for the VR6 engine), which is screwed from below into the cylinder block and constantly monitors the process of fuel combustion in the cylinders and registers the appearance in the cylinders «detonation». When uneven impacts occur, the sensor (or sensors) This informs the ECU, which does the following:

• immediately determines in which cylinder knocking has occurred and sets the ignition in it to about 3°later, leaving the ignition timing for the other cylinders the same;
• the remaining cylinders maintain the same ignition timing, and the ignition timing «delinquent» cylinder is delayed by about 3°.
• if knocking combustion is still present in the detonating cylinder, the computer delays the ignition timing by another 3°. This process can occur several times during subsequent cylinder strokes;
• only after the detonating cylinder is stable again, after a while, the ignition timing is again set to an earlier one - at each stroke of the engine, by about 0.5°, until the original ignition timing is gradually restored again.

Meanwhile, it is possible to receive information about detonation combustion in other cylinders.