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 for the following items:
- 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.
- 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 for open in ignition system ground circuit. Ensure initial ignition timing is correct.
- Inspect the items that cause an engine to run rich long term fuel trim near -13 percent.
- Inspect the items that can cause an engine to run lean long term fuel trim near 24 percent.
- Check fuel system for incorrect fuel pressure. See BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
- Check for plugged injectors. Perform injector balance test. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.
- Check for poor fuel quality or water-contaminated fuel.
- Ensure TP sensor does not stick or bind. Voltage should increase at a steady rate as throttle is moved toward Wide Open Throttle (WOT).
- Check Manifold Absolute Pressure (MAP) sensor response and accuracy. See appropriate SYSTEM & COMPONENT TESTING article.
- Inspect the engine thermostat for proper operation and for proper heat range.
- Check canister purge system for proper operation.
- Check EGR valve for proper operation.
- Check exhaust system for restrictions, such as a damaged or collapsed pipe, muffler or catalytic converter. See EXHAUST SYSTEM BACKPRESSURE under MECHANICAL INSPECTION in appropriate BASIC DIAGNOSTIC PROCEDURES article.
- Check Heated Oxygen Sensor (HO2S) for contamination. This will cause a false high voltage signal to PCM. PCM will respond by leaning out air/fuel ratio.
- Ensure correct program is installed in PCM. Check dealer for latest application.
- Check charging system output. Repair if output is less than 9 volts or greater than 16 volts.