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
Refer to "SYSTEM DIAGNOSIS/PROCEDURES and perform "DIAGNOSTIC SYSTEM CHECK."

NOTE: If emission test results show excessive CO and HC check items which cause vehicle to run RICH. Refer to "DIAGNOSTIC CHARTS/DIAGNOSTIC TROUBLE CODE (DTC) CHARTS/DTC 0172, FUEL TRIM RICH" and review "Diagnostic Aids".

If emission test results show excessive NOx, check and items which cause vehicle to run lean or too hot. Refer to "DIAGNOSTIC CHARTS/DIAGNOSTIC TROUBLE CODE (DTC) CHARTS/DTC 0171, FUEL TRIM LEAN" and review "Diagnostic Aids".
Also check EGR system operation. Refer to "DIAGNOSTIC CHARTS/C-CHARTS/CHART C-7, EGR SYSTEM FLOW CHECK."

COOLING SYSTEM
^ If the scan tool indicates a very high engine coolant temperature and the system is running lean:

CHECK:
- Engine coolant level.
- Engine thermostat for faulty part (always open) or for incorrect heat range.
- Cooling fan operation. Refer to "DIAGNOSTIC CHARTS/C-CHARTS/CHART C-12A, COOLING FAN(S) CHECK."

FUEL SYSTEM

NOTE: If the system is running rich (L.T. fuel trim below 110 with canister purge solenoid disconnected), Refer to "DIAGNOSTIC CHARTS/DIAGNOSTIC TROUBLE CODE (DTC) CHARTS/DTC 0172, FUEL TRIM RICH" and review "Diagnostic Aids".
If the system is running lean (L.T. fuel trim above 150) Refer to "DIAGNOSTIC CHARTS/DIAGNOSTIC TROUBLE CODE (DTC) CHARTS/DTC 0171, FUEL TRIM LEAN" and review "Diagnostic Aids".

^ CHECK FOR: Properly installed fuel cap.
- Incorrect fuel pressure. Refer to "DIAGNOSTIC CHARTS/A-CHARTS/CHART A-7, FUEL SYSTEM PRESSURE TEST."
- Leaking or faulty injector - Perform injector balance test. Refer to "DIAGNOSTIC CHARTS/C-CHARTS/CHART C-2A, INJECTOR COIL TEST PROCEDURE AND BALANCE TEST."
- Fuel saturated EVAP canister. Refer to "DIAGNOSTIC CHARTS/C-CHARTS/CHART C-3, EVAP CANISTER PURGE VALVE CHECK".

IGNITION SYSTEM

^ Check Spark plugs, plug wires, and ignition components. Refer to "IGNITION SYSTEM".

ADDITIONAL CHECKS

^ CHECK:
- For vacuum leaks.
- For lead contamination of catalytic converter (look for the removal of fuel filler neck restrictor).
- Carbon build-up. Remove carbon with top engine cleaner. Follow instructions on can.
- Crankcase ventilation valve for being restricted or stuck or fuel in the crankcase.
- For correct PROM (see Service Bulletins).