Rough Idle
NOTE:
Unless otherwise indicated, see appropriate SYSTEM & COMPONENT TESTING article for testing procedures.
- Check ignition timing, idle speed and throttle position sensor adjustment. See THROTTLE POSITION SWITCH, IGNITION TIMING & IDLE SPEED in ON-VEHICLE ADJUSTMENTS article.
- Check battery and charging system. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS.
- Check Idle Air Control Valve-Auxiliary Air Control (IACV-AAC) valve circuit.
- Check fuel injector circuits.
- Check fuel pump circuit.
- Check Idle Air Control Valve-Fast Idle Control Device (IACV-FICD) (where equipped).
- Check ignition circuits.
- Check PCV system.
- Check EVAP system.
- Check Exhaust Gas Recirculation (EGR) system.
- Check ECM power supply and ground circuits.
- Check Camshaft Position (CMP) sensor circuit.
- Check Mass Airflow (MAF) sensor circuit.
- Check front Heated Oxygen Sensor (HO2S) circuit.
- Check Engine Coolant Temperature (ECT) sensor circuit.
- Check Throttle Position (TP) sensor circuit.
- Check power steering pressure switch circuit.
- Check electrical load signal circuit.
- Check Park/Neutral Position (PNP) switch circuit.
- Check fuel delivery system.
- Check air intake system.
- Check engine mechanical condition.