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

^ Perform "On-Board Diagnostic (OBD) System Check."
^ IF EMISSION TEST shows excessive CO and HC check items which cause vehicle to run RICH (long term fuel trim memory less than 58), refer to "Diagnostic Aids" of DTC 45 chart. Powertrain Controls - ECM/PCM
^ CHECK: For correct EPROM (see Service Bulletins).

IGNITION SYSTEM

^ CHECK: Spark plugs and ignition components. Refer to "Electronic Ignition (EI) System."

COOLING SYSTEM

^ If the Tech 1 scan tool indicates a very high engine coolant temperature and the system is running lean:
- CHECK: Engine coolant level.
- CHECK: Engine thermostat for faulty part (always closed) or for incorrect heat range.
- CHECK: Cooling fan operation, use CHART C-12. Chart C-12 Coolant Fan Control Circuit

FUEL SYSTEM

^ CHECK: If the system is running rich (long term fuel trim near 58), refer to "Diagnostic Aids" of DTC 45 chart. Powertrain Controls - ECM/PCM
If the system is running lean (long term fuel trim 198) refer to "Diagnostic Aids" of DTC 44 chart. Powertrain Controls - ECM/PCM

^ CHECK: For properly installed fuel cap.
^ CHECK: Fuel pressure. Use CHART A-7. Related Tests, Information and Procedures
^ CHECK: Injector balance test. Use CHART C-2A. Part 3 of 3 (Fuel Injector Balance Test)
^ CHECK: Evaporative Emission (EVAP) canister for fuel loading. Use CHART C-3. Chart C-3 Evaporative Emission Control System

ADDITIONAL CHECKS

^ CHECK: For vacuum leaks.
^ CHECK: For lead contamination at three-way converter (look for the removal of fuel filler neck restrictor).
^ CHECK: For carbon build-up. Remove carbon with top engine cleaner. Follow instructions on can.
^ CHECK: EGR operation, use CHART C-7. Chart C-7 EGR System Check