Poor Fuel Economy
- Check for A/C condenser fan circuit malfunction.
- Check for Camshaft Position (CMP) sensor malfunction.
- Check for cooling fan circuit malfunction.
- Check for damaged trigger wheel on camshaft.
- Check for Diagnostic Trouble Codes (DTCs).
- Check for dragging brakes.
- Check for fuel pressure regulator malfunction.
- Check for fuel pulsation damper malfunction.
- Check for fuel pump malfunction.
- Check for fuel quality.
- Check for incorrect engine compression.
- Check for incorrect tire pressure (low).
- Check for incorrect transaxle or transmission fluid level (A/T).
- Check for incorrect valve timing due to jumped timing belt.
- Check for low coolant level.
- Check for Mass Airflow (MAF) sensor malfunction.
- Check for PCV valve malfunction.
- Check for restricted air filter.
- Check for restricted or plugged fuel lines.
- Check for restricted fuel filter or fuel intake sock.
- Check for restricted exhaust system.
- Check for spark plug malfunction.
- Check for spark plug wire malfunction.
- Check for Variable Resonance Induction System (VRIS) malfunction (Millenia and 626 2.5L).
- Check for Variable Tumble Control System (VTCS) malfunction (Miata 1.8L, Protege, Protege5 and 626 2.0L).
- Check for Variable Valve Timing (VVT) system malfunction.
- Check for weak spark from ignition system.