Detonation - Pings, Spark Knock

A mild to severe ping, usually worse under load or acceleration. Sounds like something is rattling or knocking in the engine.

POSSIBLE CAUSE ACTION



Spark timing not retarding Check timing and advance.
SEE Ignition System/ ADJUSTMENT PROCEDURES.

Lean Air-Fuel mixture Check fuel pressure.
Check Air-Fuel ratio.
Check O2 sensor output.
Perform injector balance test (MPI only).

EGR malfunction Check EGR system.
Testing and Inspection

Thermostatic Air Cleaner (TAC) Thermostatic Air Cleaner

Poor or contaminated fuel Recommend higher grade fuel