When the PCM detects a concern through the knock sensor, it commands __________ until the knock stops.

When the PCM detects a concern through the knock sensor, it commands __________ until the knock stops.

• A. Timing advance
• B. Timing retard
• C. Idle control
• D. Fuel enrichment

Answer: (B)

When detonation is detected, the system uses the knock sensor signal to pull back, or retard, the spark timing. Slowing the ignition timing lowers peak cylinder pressure and temperature, which stops the knock. Once the knock subsides, the timing can be gradually returned toward its normal value. Other actions like idle control or simply enriching the fuel mixture aren’t the immediate corrective response to knock; retarding timing is the primary immediate fix to prevent further knock.

When detonation is detected, the system uses the knock sensor signal to pull back, or retard, the spark timing. Slowing the ignition timing lowers peak cylinder pressure and temperature, which stops the knock. Once the knock subsides, the timing can be gradually returned toward its normal value. Other actions like idle control or simply enriching the fuel mixture aren’t the immediate corrective response to knock; retarding timing is the primary immediate fix to prevent further knock.