Poor Fuel Mileage
If fuel economy is lower than expected during an road test or has changed from previous road tests, check the following items:
- Check thermostat operation and heat range.
- Verify vehicle operation conditions; A/C always on, correct tire pressure, vehicle heavily loaded or constant heavy acceleration.
- Perform Diagnostic Circuit Check, see SELF-DIAGNOSTICS article.
- Check air cleaner condition.
- Check speedometer calibration.
- Perform a visual inspection of all vacuum hoses and ignition wires.
- Ensure ignition timing is correct.
- Check spark plugs for wear or damage.
- Ensure engine compression is correct.
- Ensure torque converter clutch operation is correct. See I - SYS/COMP TESTS article.
- Check brakes for dragging.
- Check exhaust system for restrictions.
- Re-check fuel mileage.