Possible Causes & Corrections
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.
Check the following items:
- Compare customer vehicle with a similar unit. Verify the customer's concern.
- Remove air filter and check for dirt or a restriction.
- Inspect transmission shift pattern and downshift operation.
- Inspect for a restricted fuel filter, contaminated fuel, or improper fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article.
- Perform the fuel injector balance test. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article.
- Inspect exhaust system for a possible restriction. See EXHAUST SYSTEM BACKPRESSURE under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article.
- Inspect exhaust system for damaged or collapsed pipes. Inspect the muffler for heat distress or a possible internal failure.
- Inspect control module grounds for being clean, tight, and in their proper location.
- Inspect Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.
- Inspect A/C operation. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
- Test generator output voltage.
- Monitor Knock Sensor (KS) system for retarded timing.
- Engine compression. Low compressions can be caused by faulty valve timing or improper or worn camshaft.