Knock Sensor (KS) Description and Operation

Description

Knock is a phenomenon characterized by undesirable vibration and noise that may lead to engine damage. The Knock Sensor (KS) is installed on the cylinder block and detects engine knock. When knock occurs, vibration from the cylinder block is applied as pressure to the piezoelectric element. When knock occurs, the sensor outputs a voltage signal. The ECM retards ignition timing when knock occurs. If knock disappears after retarding ignition timing, the ECM advances ignition timing. This sequential control can improve engine power, torque and fuel economy.