Incomplete Combustion

DOES NOT START / INCOMPLETE COMBUSTION

Check in the order shown
1. Volume air flow sensor circuit.
2. Idle speed control motor.
3. Fuel pressure regulator.
4. Engine coolant temperature sensor circuit.
5. Compression.
6. Piston rings.
7. Ignition timing.
8. Timing belt.
9. Injectors.
10. Engine control module.