GM Astro/Safari 1985-1996 Repair Guide

Engine Detonation (Dieseling)


When the engine operates beyond the controlled limits, replace or repair the following items or systems, as necessary:

Faulty ignition electrical system components.
The ignition timing may be too far advanced.
Inoperative Exhaust Gas Recirculation (EGR) valve.
Inoperative Positive Crankcase Ventilation (PCV) valve.
Faulty or loose spark plugs.
Clogged fuel delivery system.
Sticking, leaking or broken valves.
Excessive deposits in the combustion chambers.
Leaks in the vacuum system.