Anti-Knock Control

Ignition maps are designed for optimal engine operation. Under some circumstances combustion knock can occur. Anti-knock control is integrated into the engine control module. The engine control module identifies the knocking cylinder and retards ignition timing of affected cylinder.

When engine control module detects ignition knock, ignition timing is retarded 3 degrees at the next ignition cycle (spark plug firing). If cylinder continues to knock, ignition timing is retarded another 3 degrees at the next ignition cycle.

If knocking continues, ignition timing will continue to be retarded for a maximum of 12 degrees. Ignition timing will only be advanced when knocking ceases or engine coolant temperature reaches 176-194°F (80-90°C) to prevent engine overheating. If knocking ceases, ignition timing for affected cylinder is advanced .35 degree per ignition cycle (spark plug firing) until nominal value is reached.