Hyundai Elantra MD/UD: Knock Sensor (KS). Description and Operation
Description
Knocking is a phenomenon characterized by undesirable vibration and noise
and can cause engine damage. Knock Sensor (KS) is installed on the cylinder
block and senses engine knocking.
When knocking occurs, the vibration from the cylinder block is applied
as pressure to the piezoelectric element. When a knock occurs, the sensor produces
voltage signal. The ECM retards the ignition timing when knocking occurs. If
the knocking disappears after retarding the ignition timing, the ECM will advance
the ignition timing. This sequential control can improve engine power, torque
and fuel economy.
