Detonation/Spark Knock

Definition: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.

POSSIBLE CAUSE ACTION

Lean operating condition Check computer controls
Refer to COMPUTERIZED ENGINE CONTROLS

Poor or contaminated fuel [1] Check for excessive fuel alcohol content

Incorrect fuel pressure See FUEL PUMP AND PRESSURE REGULATOR (SYSTEM PRESSURE CHECKS)
under COMPONENT TESTING

Vacuum leak Inspect vacuum hoses for
proper routing and damaged lines
Check intake manifold and
throttle chamber base


[1] Mazda reccommends the use of UNLEADED REGULAR gasoline only, in all vehicles not equipped with a turbocharger. Do not use, or reccommend for use, any higher octane fuels. Starting, idle, and driveability problems may result. See factory Technical Service Bullitin #054/89, titled "USE OF REGULAR UNLEADED GASOLINE".