1. Autos
SPARK KNOCK

Definition: This is the pinging or rattling noise sometimes heard during acceleration that indicates detonation is occurring inside the engine (See Detonation).
Related Terms
Detonation

Spark knock can be caused by a variety of things including using low octane fuel, over-advanced ignition timing, too much compression (often due to a buildup of carbon in the combustion chamber), by an inoperative EGR valve, and/or by too much heat. If switching to a higher octane fuel doesn't cure the problem, the cause should be investigated because prolonged or heavy knocking can damage the engine.

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