Excessive Exhaust Emissions or Odors - With PCM

DEFINITION
Vehicle fails an emission test. Vehicle has excessive "rotten egg" smell. Excessive odors do not necessarily indicate excessive emissions.

PRELIMINARY CHECKS
- Refer to Important Preliminary Checks, as described at start of Diagnosis By Symptom. Testing and Inspection
- Perform Diagnostic System Check. Testing and Inspection
- Make sure engine is at normal operating temperature.
- If EMISSION TEST shows excessive CO and HC check items which cause vehicle to run RICH. Long term fuel trim memory less than 115 refer to DTC 45 Diagnostic Aids. Powertrain Controls - ECM/PCM
- If EMISSION TEST shows excessive Nitrogen Oxide (NOx) check items which cause engine to operate LEAN or too hot.
- Service Bulletins for updates.

SENSORS
Check:
- If the scan tool indicates a very high coolant temperature and the system is running LEAN: check the cooling system and cooling fan for proper operation.

FUEL SYSTEM
Check:
- If the system is running rich, (long term fuel trim less than 115), refer to DTC 45 Diagnostic Aids Powertrain Controls - ECM/PCM
If the system is running lean, (long term fuel trim greater than 150), refer to DTC 44 Diagnostic Aids. Powertrain Controls - ECM/PCM
- For properly installed fuel cap.
- Fuel pressure. Refer to Chart A-6. Related Tests, Information and Procedures
- Canister for fuel loading.
- Injector balance test. Refer to Chart A-7 of appropriate engine VIN. Related Tests, Information and Procedures

IGNITION SYSTEM
Check:
- Ignition system, incorrect timing, or excessive advance.
- Spark plugs, plug wires, and ignition components.

ADDITIONAL CHECKS
Check:
- For vacuum leaks.
- For lead contamination of catalytic converter (look for the removal of fuel filler neck restrictor).
- Carbon buildup. Remove carbon with top engine cleaner. Follow instructions on can.
- EGR valve for not opening.
- Crankcase ventilation valve for being plugged, stuck or blocked crankcase ventilation hose.