Possible Causes & Corrections
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Check the following items:
- Ensure customer has an actual problem.
- Compare scan tool data at idle with scan tool data list. See PID VALUE CHARTS in PID VALUE CHARTS - SILVERADO & SIERRA article.
- Inspect fuel quality.
- Observe the actual vs. desired fuel rail pressure with a scan tool, with engine running.
- Inspect fuel injectors using Tech 2 scan tool.
- Inspect Engine Coolant Temperature (ECT) sensor. Use scan tool in order to compare ECT with the ambient air temperature on a cold engine. If coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, inspect for a high resistance in coolant sensor circuit or the sensor itself.
- Inspect glow plug system operation.
- Inspect Fuel Rail Pressure (FRP) sensor. Use scan tool to observe FRP with engine off. FRP should be 1.1-1.4 MPa. If not, inspect for high resistance in the low reference or 5-volt reference circuits or the sensor.
- Inspect for a restriction in the air cleaner or air intake ducts.
- Inspect for a restriction in the turbocharger charge air cooler.
- Inspect for a restriction in the intake manifold.
- Inspect for an air leak in the charge air cooler with a Charge Air Cooler Tester (J-46091).
- Inspect for an air leak in the air ducts between turbocharger and intake manifold.
- Inspect for incorrect basic engine parts such as the camshafts, cylinder heads, pistons, etc.
- Inspect for excessive oil entering the combustion chamber.