Poor Fuel Mileage
- Check for fuel leaks.
- Check for clogged air filter.
- Check compression.
- Check fuel pressure.
- Check cooling system.
- Check ignition and valve timing.
- Check spark plugs.
- Check for faulty throttle position sensor (if equipped).
- Check for faulty coolant (water) temperature sensor.
- Check for faulty ECM.
- Check for high idle RPM.
- Check for malfunctioning electronic fuel injection system.
- Check for malfunctioning distributor mechanical and vacuum advance (if equipped).
- Check for malfunctioning EGR valve (if equipped).
- Ensure sufficient secondary spark is available.