Knock Sensor: Description and Operation

PURPOSE
Two knock sensors detect engine knock and send a signal to the PCME. When knocking occurs, the PCME retards ignition timing until knock ceases.

LOCATION
One each on the side of each cylinder head.

OPERATION
The knock sensors contains a crystal element with electrodes attached to opposing sides. When the crystal structure is distorted, a small voltage potential is created between opposite sides. When a knock of sufficient intensity and frequency occurs, the crystal is distorted slightly, generating a voltage signal that the PCME can detect.