Rough Or Unstable Idle
- Check temperature sensor operation.
- Check for proper CO setting (if adjustable) on mass airflow meter. Check for broken mass airflow meter filament. Check mass airflow meter resistance.
- Check induction system. Check for vacuum leaks downstream of throttle valve. Inspect duct between mass airflow meter and throttle body.
- Check idle speed and EGR valve (if equipped) pulse ratio.
- Check injector operation and opening duration. Check injectors for leaks.
- Ensure fuel pump is okay. Check fuel pressure and pressure regulator. Check for leaks in fuel lines or restrictions in return line.
- Ensure electrical harness, connectors and wires are not broken or loose. Check all input signals to ECU.
- Check EGR valve (if equipped) for proper operation.
- Check oxygen sensor.