Knock Sensor: Description and Operation

Bank 1 And Bank 2 Knock Sensors (KS):

The Knock Sensor (KS) system detects engine detonations. The knock sensor module is employed in the ECM. The ECM will retard the spark timing based on the signals from the KS module. The knock sensors produce an AC voltage that is sent to the KS module. The amount of the AC voltage produced is proportional to the amount of knock.

The control module reads the voltage of the sensor during the 45 degrees after cylinder 2, 4, or 6 has fired and the voltage of the sensor during the 45 degrees after cylinder 1, 3, or 5 has fired.

If knock occurs in any of the cylinders, the ignition will be retarded by 3 degrees for that particular cylinder. If the knocking then stops, the ignition will be restored to what it was before in steps of 0.75 degrees.

Should knocking continue in the same cylinder in spite of the ignition being retarded, the control module will retard the ignition an additional step of 3 degrees, and so on, up to a maximum of 12.75 degrees. The ignition will also be retarded at high ambient temperatures in order to counteract knocking tendencies provoked by high intake air temperatures.

Should either the bank 1 or the bank 2 sensor fail to work, or should a break in the circuit occur, no continuity, the ignition timing will then use a default strategy that will retard the ignition much more than normal.