Knock Sensor Module: Description and Operation

Approximate Reaction Time At 3000 rpm:

Anti Knocking Correction

The knock sensor is used to prevent spark knocking (detonation). If a signal from the knock sensor is detected for more than approximately one second the ignition timing is retarded. To avoid errors, the signal from the knock sensor is only processed by the control unit when:
- Engine coolant temperature is above 50°C (122°F)
- Intake manifold pressure is above 0.7 bar

When spark knock is heard by the sensor the ignition timing is retarded by 2.7°. If no further knocking occurs, the ignition timing is returned to its original programmed value in steps of 1.3°.

If engine knocking continues after the first step of retard, the timing is retarded two additional steps of 2.7° each until a total retard of 8° is reached. If no further knocking occurs the timing is then advanced back in steps of 1.3°.

If knocking continues after the timing has been retarded the maximum 8°, the wastegate solenoid is activated to open the wastegate and the engine control warning indicator light will come on. This tells the driver to release the accelerator and decrease the engine load. The wastegate solenoid will close once engine knocking has stopped and the ignition timing has been returned to its correct value.