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 for the following items:
- Inspect the fuel supply system vacuum.
- Inspect for water contamination in the fuel.
- Perform Fuel Injector Balance Test using a Tech 2 scan tool.
- Inspect for high fuel supply system vacuum after a cold start or during moderate or full throttle acceleration. If the vacuum jumps above specification, there is a restriction in fuel system.
- Inspect Fuel Rail Pressure (FRP) sensor. Observe the FRP with a scan tool. The FRP reading should be between 1.1-1.4 MPa. If not, inspect for high resistance in FRP sensor circuits or FRP sensor.
- Test for an intermittent FRP sensor signal by wiggling the harness between sensor and ECM with ignition on, engine off, while monitoring the parameter with a scan tool.
- Observe FRP sensor and fuel pressure regulator commanded percent at idle. FRP should be near 40 MPa, and commanded percent should be near 40 percent. If command is high, a fuel pressure or sensor problem exists.
- Inspect for an intermittent Crankshaft Position (CKP) sensor signal.
- Inspect CKP sensor reluctor wheel. Remove CKP sensor and attempt to move the reluctor wheel front to back or side-to-side with a probe. If there is any movement, the reluctor wheel retaining bolts are loose.
- Check Service Bulletins for control module software updates.
- Compare scan tool data at idle with scan tool data list. See PID VALUE CHARTS in PID VALUE CHARTS - SILVERADO & SIERRA article.
- Inspect generator output voltage.