Diagnostic Aids

WARNING: This page is about a different car, the 2002 GMC Savana and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

Check for the following items:

A loose or missing distributor hold-down bolt.
A loose CMP sensor causing a variance in the sensor signal.
An incorrectly installed distributor. 1 tooth off in either advance or retard positions.
A loose distributor rotor on the distributor shaft.
Excessive free play in the timing chain and gear assembly.

If an intermittent condition is suspected, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.