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 for the following items:
- Ensure driver understands the torque converter clutch operation and A/C compressor operation.
- Ensure that transmission fluid is at 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.
- Check fuel pressure while the condition exists. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article.
- Inspect in-line fuel filter for restrictions.
- Check for proper ignition output voltage using Spark Tester (J-26792). Inspect spark plugs. Remove plugs and inspect for wetness, cracks, wear, improper gap, burned electrodes or heavy deposits.
- Check the secondary ignition system and spark plugs. Remove plugs and inspect them for wetness, cracks, wear, improper gap, burned electrodes or heavy deposits.
- Check for a loose or damaged Crankshaft Position (CKP) sensor and reluctor wheel.
- Inspect control module grounds for being clean, tight, and in their proper locations.
- Test generator output voltage.
- Inspect vacuum hoses for kinks or leaks.
- Check for an intermittent EGR problem.
- Inspect TCC operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.
- 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.