Knock may result from improper ______ calibration.

Knock may result from improper ______ calibration.

• A. Fuel
• B. Ignition
• C. Spark
• D. Timing

Answer: (C)

Knock happens when the air–fuel mixture ignites at the wrong moment, causing a sharp pressure rise inside the cylinder. The spark plug initiates combustion, and its firing timing is set by spark calibration. If that calibration is off, the spark can fire too early or too late, so the burn starts at an inappropriate time and creates pressure waves that knock. Fuel quality or mixture can influence knock too, but the direct link to knock through calibration is the spark itself—mis-timed ignition leads to detonation rather than a smooth, controlled burn.

Knock happens when the air–fuel mixture ignites at the wrong moment, causing a sharp pressure rise inside the cylinder. The spark plug initiates combustion, and its firing timing is set by spark calibration. If that calibration is off, the spark can fire too early or too late, so the burn starts at an inappropriate time and creates pressure waves that knock. Fuel quality or mixture can influence knock too, but the direct link to knock through calibration is the spark itself—mis-timed ignition leads to detonation rather than a smooth, controlled burn.