Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2003 GMC Sonoma, 2003 GMC Safari, 2003 GMC Jimmy, 2003 Chevrolet S10 Pickup, and 2003 Chevrolet Blazer. However, it is still accessible from the selected car via links, so may be relevant.

Inspect for the following conditions:

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 position).
A loose distributor rotor on the distributor shaft.
Excessive free play in the timing chain and gear assembly.

If the condition is intermittent, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article.