Knock Control System

Knock Sensor:

PCM With Knock Sensor Module:

PURPOSE
Varying octane levels in today's gasoline can cause detonation in high performance engines. Detonation is sometimes called spark knock.

The Knock Sensors (KS) send a signal to the Powertrain Control Module (PCM) to retard ignition timing up to 20 degrees during a spark knock condition. When engine detonation stops and there is no knock signal being sent to the PCM, timing is advanced in small increments. This allows the PCM to maintain maximum timing advance under various engine load conditions.

OPERATION
When abnormal engine vibrations (spark knock) are present, the sensors produce an AC voltage signal. The amount of AC voltage produced by the sensors is determined by the amount of knock. These signals are received by the PCM via the knock sensor module. The PCM fluctuates ignition timing to maximize performance and minimize spark knock.