Fails Emission Test
- Ensure air intake system is not restricted.
- Ensure engine is at normal operating temperature.
- Ensure fuel system pressure is correct.
- Check cold start valve for leaking (engine warm).
- Check thermo time switch operation.
- Ensure base timing is correct.
- Check for correct PCV valve operation.
- Check crankcase for fuel contamination.
- Check idle stabilizer operation.
- Check EGR system for correct operation. (if equipped)
- Check vapor recovery system operation.
- Check operation of coolant temperature sensor.
- Check operation of Oxygen (O2) sensor.
- Check fuel tank filler tube for tampering of restrictor. If tampering has occurred, check catalytic converter for lead contamination and exhaust system restriction.
- Check for poor quality fuel containing insufficient cleaning additives.
NOTE:
Prolonged use of poor quality fuel can cause injector clogging and carbon build-up on intake system.