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 the following items:
- Inspect 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 observe fuel economy.
- Suggest to owner to refer to Important Facts on Fuel Economy in the owner's manual.
- Inspect fuel type, quality and alcohol content.
- Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP 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.
- Check ignition wires for cracking, hardness and proper connections.
- Inspect Knock Sensor (KS) system operation. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article.
- 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.