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 the following items:
- Inspect the air cleaner element or filter, for dirt or being plugged.
- Visually and physically check the vacuum hoses for splits, kinks, and proper connections as shown on the underhood Vehicle Emission Control Information label.
- Discuss the driving habits with the owner. Check if A/C is ON full time or if defroster mode is ON? Check tires for proper inflation. Check that wheel and tires are the correct size. Check for excessively heavy loads being carried or an aggressive driving habits
- Suggest to owner to fill the fuel tank and to inspect the fuel economy.
- Suggest to driver to refer to Important Facts on Fuel Economy in the owner manual.
- Inspect fuel type, quality and alcohol content.
- Test fuel pressure. Refer to FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.2L BRAVADA, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article.
- Inspect spark plugs. Remove and check for wet plugs, cracks, wear, improper gap, burned electrodes or heavy deposits.
- Inspect for an open Ignition Control (IC) circuit.
- Inspect Knock Sensor (KS) system operation.
- Inspect engine coolant level.
- Inspect engine thermostat for being open or for wrong heat range.
- Inspect transmission shift pattern.
- Inspect Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.
- Inspect for proper calibration of the speedometer.
- Inspect for dragging brakes.