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:
- Ensure park/neutral switch is properly adjusted.
- Check transmission shift solenoid system and Torque Converter Clutch (TCC) system for proper operation.
- Ensure owner understands operation of TCC and A/C compressor clutch, as stated in owners manual.
- 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 engine compression. Check for incorrect valve timing, bent push rods, broken valve springs or worn camshaft lobes.
- Visually check vacuum hoses for splits, kinks and proper connections as shown on vehicle emission control information label.
- Check for proper Crankshaft Position (CKP) and Camshaft Position (CMP) sensor resistance. Check for intermittent ignition feed or ground circuits.
- Ensure initial ignition timing is properly set.
- Using Spark Tester (J-26792), check for adequate spark output.
- Remove spark plugs, and check for wet/fouled spark plugs, cracks in porcelain, improper gap, burned electrodes or heavy carbon deposits. Check spark plug wires.
- Check Knock Sensor (KS) system for excessive retard.
- Check in-line fuel filter. Replace if dirty or clogged.
- Check fuel for water contamination.
- Check fuel system for incorrect fuel pressure. See BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
- Check fuel injectors. Perform injector balance test. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.
- Check the HO2 sensors. The HO2 sensors should respond quickly to different throttle positions.
- Check the MAF sensor and intake air system for proper connections.
- If emission test shows excessive oxides of nitrogen (NOx) emissions, check all systems and components which could cause engine to run lean or to run too hot. Check EGR system. Check for an inoperative cooling fan.
- Check canister purge system for proper operation.
- Check EGR valve for proper operation.
- 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.
- Check PCM grounds. Ensure they are clean, tight and properly located.
- Check charging system output. Repair if output is less than 9 volts or greater than 16 volts.