Possible Causes & Corrections
WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Check for the following items:
- Ensure driver understands the torque converter clutch operation and A/C compressor operation.
- Ensure that the transmission fluid is at the proper level.
- Display scan tool parameters for the various engine controls sensors. Inspect for any abnormal readings.
- Inspect for a rich or lean symptom that causes the condition. Drive vehicle at the speed of the complaint. Monitoring the fuel trim will help identify the condition.
- Lean condition. The long term fuel trim will be more than 150 displayed on scan tool.
- Rich condition. The long term fuel trim will be less than 115 displayed on scan tool.
- Test fuel pressure while the condition exists. Refer to FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.2L BRAVADA, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article.
- Inspect the in-line fuel filter for a restrictions.
- Inspect spark plugs. Remove plugs and inspect for wetness, cracks, wear, improper gap, burned electrodes or heavy deposits.
- Inspect the control module grounds for being clean, tight, and in their proper locations.
- Test the generator output voltage.
- Inspect vacuum hoses for kinks or leaks.
- Inspect TCC operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.
- Inspect exhaust system for a possible restriction.