- Faulty Idle Air Control Valve (IACV): The IACV regulates the amount of air that bypasses the throttle valve when the engine is idling. If its dirty, or malfunctioning it may cause idle dipping issue as the engine cannot properly regulate its intake air.
- Vacuum Leak: A vacuum leak in the intake system can cause a lean fuel mixture and low idle speed. Check all the vacuum hoses and connections for leaks or cracks.
- Throttle position sensor issues (TPS) could cause the engine to cut out if the sensor is not providing the correct data to the engine computer (ECU) TPS issues may also cause the engine to stumble or hesitate when accelerating.
- Faulty Oxygen Sensor: The Oxygen Sensor monitors the amount of unburned oxygen in the exhaust and helps adjust the fuel mixture accordingly.
If the oxygen sensor is faulty, the ECU cannot get the correct feedback about the air-fuel ratio and might adjust it incorrectly leading to idle dipping
Troubleshooting Steps:
1. Check for Vacuum leaks: inspect all the vacuum hoses and connections for leaks or cracks. Repair any leaks if found.
2. Clean the IACV: Remove the IACV from the throttle body and clean it thoroughly with throttle body cleaner. Make sure to clean both the valve and the ports on the throttle body
3. Test the TPS: Check the Throttle Position Sensor (TPS) voltage with a multimeter. If the TPS voltage is not within the specified range, replace the sensor.
4. Check/replace the Oxygen sensor: You can check the Oxygen sensor by disconnecting it and observe if the idle behavior improves. If it does, the oxygen sensor is faulty and should be replaced.
Additional Tips
- Inspect the fuel system such as fuel filter and fuel pump.
- Perform a fuel injection system cleaning or servicing if necessary.
-Check spark plugs and ignition system components to make sure they are functioning properly and the engine is receiving adequate spark.
- Inspect the air filter to ensure its not restricted and clean if needed.
