ROUGH, UNSTABLE OR INCORRECT IDLE, STALLING
Engine runs unevenly at idle. If severe enough, vehicle will shake. Idle may vary in RPM. Either problem may cause stalling. Engine idles at incorrect RPM.
Possible Cause & Correction
Check the following items:
Ensure throttle linkage and/or TP sensor is not sticking or binding. Ensure throttle bore is free of
Check for proper operation of crankshaft position sensor.
Check for proper operation of camshaft position sensor.
Check for vacuum leaks.
Check engine idle speed (both base idle and PCM idle).
Check Idle Air Control (IAC) system. Check for vacuum leak or high idle. Check for alcohol contaminated fuel, incorrect fuel pressure or a restricted injector. Check for foreign material in
IAC bore of throttle body. Check for proper connection of IAC valve electrical connector. Check
for failure of A/C compressor or relay.
Check for proper operation of EGR system.
Check charging system output. Repair charging system if voltage is less than 9 volts or more than
Check for fuel in pressure regulator vacuum hose. If fuel is present, replace regulator.
Check evaporative emission control system.
Check for proper spark plug gap, and check engine compression.
Check PCM grounds for clean and tight connections.
Check Manifold Absolute Pressure (MAP) or Mass Airflow (MAF) sensors for proper operation.
Monday, February 23rd, 2009 AT 9:08 PM