Possible Causes & Corrections
WARNING: This page does not describe the selected car, but rather 34 other vehicles, including the 2002 Saturn Vue, 2002 Pontiac Montana, 2002 Pontiac Aztek, 2002 Oldsmobile Silhouette, and 2002 Oldsmobile Bravada. However, it is still accessible from the selected car via links, so may be relevant.
Check the following items:
- Check for restricted exhaust system. See EXHAUST SYSTEM BACKPRESSURE under MECHANICAL INSPECTION in appropriate BASIC DIAGNOSTIC PROCEDURES article.
- Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. If a cylinder can be located with a misfire, see appropriate SELF-DIAGNOSTICS article.
- Check engine compression. Check for incorrect valve timing, bent push rods, broken valve springs or worn camshaft lobes.
- Using Spark Tester (J-26792), check for adequate spark at spark plugs.
- Check ignition system for faulty ground and power feed circuits.
- Check for proper Crankshaft Position (CKP) and Camshaft Position (CMP) sensor resistance.
- Remove spark plugs and check for wet plugs, cracks, improper gap, burned electrodes or heavy carbon deposits. Also, check condition of spark plug wires. Spray spark plug wires with a fine mist of water to check for shorts.
- Check Transaxle Range (TR) switch input with vehicle in drive and shifter in drive or overdrive.
- Check for poor quality or alcohol contaminated fuel.
- Check fuel injectors. Perform injector balance test. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.
- Check fuel system for incorrect fuel pressure. See BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
- Inspect items that cause an engine to run rich, long term fuel trim near -13 percent.
- Inspect items that can cause an engine to run lean, long term fuel trim near 24 percent.
- Check PCM grounds. Ensure they are clean, tight and properly located.
- Check TP sensor for sticking and binding. Check for correct TP sensor voltage. See FUEL SYSTEMS in appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article.
- Use a scan tool in order to monitor the Knock Sensor (KS) system for excessive spark retard activity.