Diagnostic Aids

Inspect for the following conditions:

• High resistance in an IAC valve control circuit
• The correct positive crankcase ventilation (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 the mass air flow (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 throttle position (TP) sensor
• Excessive deposits in the IAC passage or on the 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 can not be overcome by the IAC valve. Refer to Symptoms - Engine Controls .
• If the problem is determined to be intermittent, refer to Intermittent Conditions .