Excessive Exhaust Emissions or Odors

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

PRELIMINARY CHECKS
^ Perform the careful visual / physical checks as described in Preliminary Checks.
^ Perform "On-Board Diagnostic System Check."
^ 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 Procedures / Diagnostic Charts / Code 45 Oxygen Sensor Circuit. Testing and Inspection
^ If EMISSION TEST shows excessive NOx check items which cause engine to operate LEAN or too hot.

SENSORS
^ 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
^ If the system is running rich, (long term fuel trim less than 115), refer to Procedures / Diagnostic Charts / Code 45 Oxygen Sensor Circuit, "Diagnostic Aids". Testing and Inspection
or if the system is running lean, (long term fuel trim greater than 150), refer to Procedures / Diagnostic Charts / Code 44 Oxygen Sensor Circuit, "Diagnostic Aids". Testing and Inspection
^ Check for properly installed fuel cap.
^ Check fuel pressure, refer to Procedures / Diagnostic Charts / Chart A-6 Fuel System Diagnosis. Testing and Inspection
^ If test shows excessive NOx, check items which cause engine to operate LEAN or too hot.
^ Check EVAP fuel canister for fuel loading, refer to Procedures / Diagnostic Charts / C Charts / Canister Purge Solenoid. Testing and Inspection

IGNITION SYSTEM
^ Check ignition system for incorrect timing or excessive advance. Refer to Procedures / Diagnostic Charts / C Charts / Distributor Ignition System Check. Testing and Inspection
^ Check Spark plugs, plug wires, and ignition components.

ADDITIONAL CHECKS
^ Check For vacuum leaks.
^ Check For lead contamination of catalytic converter (look for the removal of fuel filler neck restrictor).
^ Check Carbon build-up. Remove carbon with top engine cleaner. Follow instructions on can.
^ Check the Exhaust Gas Recirculation (EGR) valve for not opening, refer to Procedures / Diagnostic Charts / C Charts / EGR System Check. Testing and Inspection
^ Check Crankcase ventilation valve for being restricted or stuck or fuel in the crankcase.