Excessive Exhaust Emissions (Odors)

Definition: Vehicle fails an emission test or vehicle has excessive "rotten egg" smell. (Excessive odors do not necessarily indicate excessive emissions).

Perform careful visual and physical check as described at the beginning of Symptoms.

Perform "Diagnostic Circuit Check."

^ CHECK
- EGR valve not opening.
- Vacuum leaks.
- Faulty coolant system and/or coolant fan operation. Use CHART C-12. Testing and Inspection
- Remove carbon with top engine cleaner. Follow instructions on can.
^ If the system is running RICH (block learn less than 118), refer to "Diagnostic Aids" of Code 45. Powertrain Controls - ECM/PCM
^ If the system is running LEAN (block learn greater than 138), refer to "Diagnostic Aids" of Code 44. Powertrain Controls - ECM/PCM
^ If emission test indicates excessive NOx, check for items which cause car to run lean or too hot.
^ If emission test indicates excessive HC and CO or exhaust has excessive odors, check for items which cause car to run RICH.
- Incorrect fuel pressure. Use CHART A-7. Chart A-7 Fuel System Pressure Test
- Fuel loading of evaporative vapor canister.
- PCV valve plugging, sticking, or blocked [1][2]PCV hose. Check for fuel in crankcase.
- Catalytic converter lead contamination (Look for removal of fuel filler neck restrictor).
- Improper fuel cap installation.
- Faulty spark plugs, plug wires, or ignition components. See IGNITION SYSTEM. Ignition System