Diagnostic Aids
WARNING: This page is about a different car, the 2003 GMC Savana and 2003 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
Inspect for the following conditions:
- High resistance in an IAC valve control circuit.
- The correct PCV valve, properly installed and proper operation of the PCV valve.
- Proper operation and installation of all air intake components.
- Proper installation and operation of MAF sensor, if equipped.
- A tampered with or damaged throttle stop screw.
- A tampered with or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage, if equipped.
- A skewed high TP sensor.
- Excessive deposits in the IAC passage or on IAC pintle.
- Excessive deposits in the throttle bore or on the throttle plate.
- Vacuum leaks.
- A high or unstable idle condition could be caused by a non-IAC system problem that cannot be overcome by the IAC valve.
- For intermittent conditions, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.3L CHEVY EXPRESS & SAVANA article.