Excessive Exhaust Emissions (Odors)

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

PRELIMINARY CHECKS
1. Perform diagnostic system check. Refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic System Check.

NOTES:
^ If EMISSION TEST shows excessive Carbon Monoxide (CO) and Hydrocarbons (HC) check items which cause vehicle to run RICH (long term fuel trim less than 110), refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Code 45. Powertrain Controls - ECM/PCM
^ If EMISSION TEST shows excessive Oxides Of Nitrogen (NOx), check items which cause vehicle to run lean or too hot.

ADDITIONAL CHECKS
1. Check For vacuum leaks.
2. Check the Exhaust Gas Recirculation (EGR) valve for not opening. Refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Chart C-7. Chart C-7 EGR System Check
3. Check For lead contamination for catalytic converter (look for the removal of fuel filler neck restrictor).
4. Check for carbon build-up. Remove carbon with top engine cleaner. Follow instructions on can.
5. Check the crankcase ventilation valve for being plugged or stuck or fuel in the crankcase.
6. Check service bulletins for updates.

IGNITION SYSTEM
Check the spark plugs, plug wires, and ignition components.

COOLING SYSTEM
If the Tech 1 scan tool indicates a very high engine coolant temperature and the system is running lean:
1. Check the engine coolant level.
2. Check the engine thermostat for faulty, part (always) open or for wrong heat range.
3. Check the cooling fan operation, refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Chart C-12. Chart C-12 Coolant Fan Control Circuit

FUEL SYSTEM
1. Check For a properly installed fuel cap.
2. Check the Fuel pressure. Refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Chart A-7. Related Tests, Information and Procedures
3. Check Fuel injector coil/balance test. Refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Chart C-2A. Chart C-2A Fuel Injector Balance Test
4. Check canister for fuel loading. Refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Chart C-3. Chart C-3 Evaporative Emission Control System

NOTES:
^ If the system is running RICH (long term fuel trim near 110), refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Code 45. Powertrain Controls - ECM/PCM
^ If the system is running LEAN (long term fuel trim near 150), refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Code 44. Powertrain Controls - ECM/PCM