Knock Sensor: Description and Operation

DIGIFANT II




Knock Sensor

The knock sensor is attached to the left side of the cylinder block next to cylinder #2. It is a piezoelectric crystal encased in a metal and plastic housing.

Vibrations in the engine will cause the quartz crystal in the knock sensor to generate a small voltage. By monitoring this voltage, the ignition control unit can determine when ignition knock or detonation occurs. The ignition control unit will then retard the ignition timing to prevent the ignition knock.

The construction of the knock sensor is slightly different than previous versions. A steel bushing is located inside the sensor housing. This is to prevent the quartz crystal inside the sensor from being crushed or damaged by overtightening the installation bolt.

The torque for the knock sensor bolt is: 20-25 Nm (15-18 ft-lbs.)