Incorrect Idle At Engine Start-Up
* Check for defective throttle linkage or cable.
* Check throttle opener or dashpot (if equipped).
* Check idle air control valve (if equipped) and wiring.
* Check Engine Control Module (ECM) and wiring.
* Check Throttle Position (TP) sensor and wiring.
* Check A/C signal circuit to Engine Control Module (ECM).
* Check park/neutral position switch signal to Engine Control Module (ECM).
* Ensure dipstick and oil filler cap are properly seated. Engine Idle Speed Remains High
* Check for defective throttle linkage or cable.
* Check dashpot or throttle opener (if equipped).
* Check idle air control valve (if equipped) and wiring.
* Check Throttle Position (TP) sensor and wiring.
* Check A/C signal circuit to Engine Control Module (ECM).
* Check park/neutral position switch signal to Engine Control Module (ECM).
* Check fuel injectors.
* Check Engine Control Module (ECM) and wiring. Engine Idle Speed Remains Low
* Check idle air control valve (if equipped) and wiring.
* Check airflow meter or MAP sensor and wiring.
* Check fuel injectors.
* Check Engine Control Module (ECM) and wiring. Rough Engine Idle
* Check for vacuum leaks.
* Check EGR system.
* Ensure proper spark exists from ignition system.
* Ensure ignition timing is correct.
* Ensure fuel system performs properly (fuel pump, fuel filter, fuel injector and fuel pressure regulator).
* Check engine compression, valve clearance, valve timing and timing belt (if equipped).
* Check airflow meter or MAP sensor and wiring.
* Check Engine Control Module (ECM) and wiring.
* Ensure dipstick and oil filler cap are properly seated. Engine Misfires
* Check EGR system.
* Ensure proper spark exists from ignition system.
* Ensure ignition timing is correct.
* Check engine compression, valve clearance, valve timing and timing belt (if equipped).
* Check fuel injectors.