DETONATION (KNOCK) RETARD OPERATION
The 929S and turbocharged models use a ignition retard system consisting of knock sensor(s) and knock control unit. The knock sensor detects engine detonation (knocking) in the engine and sends a signal to knock control unit. This signal is modified by the knock control unit and sent to the ECU.
Timing can be retarded up to 6 degrees, depending upon amount of knocking. On MX-6 turbo and 626 turbo models, knock control unit also controls turbocharger wastegate solenoid valve, lowering turbo boost pressure up to 2.2 psi during knock conditions.