Knock Sensor: Description and Operation

Knock Sensor:

PURPOSE
To sense engine knock or detonation and send an electrical signal to the Engine Control Module (ECM).

DESCRIPTION
The knock sensor's piezoelectric element detects engine detonation. A knocking vibration from the cylinder block is sensed as vibration pressure. This pressure is converted into a voltage signal and sent to the ECM. The ECM then adjusts ignition timing accordingly.


CONSTRUCTION
The knock sensor(C), consists of a (3) housing, a (4) piezoelectric crystal mounted on a (5) threaded sleeve between (6) two connector strips. One side of the assembly is fitted with a (7) damping weight and (8) spring washer secured by a (9) nut.