Knocking is a phenomenon characterized by undesirable
vibration and noise that can cause engine damage. Two Knock Sensors (KS)
are installed inside the V-valley of the cylinder block to sense engine
knocking.
When knocking occurs, the vibration from the cylinder block is applied as pressure to the piezoelectric element.
When a knocking 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.