Upgraded Emissions

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

PRELIMINARY CHECKS
If EMISSION TEST shows excessive CO and HC, check items which cause vehicle to run RICH (HO2S voltage above 450 mV). Make sure engine is at normal operating temperature.

If EMISSION TEST shows excessive NOx check items which cause vehicle to run LEAN or too hot (HO2S voltage below 450 mV). Make sure engine is at normal operating temperature.

SENSORS

NOTICE: If a Tech 1 scan tool (or equivalent) indicates a very high engine coolant temperature and the system is running LEAN, check for proper operation of the electric radiator fan.

FUEL SYSTEM
CHECK: For proper fuel filler cap.
Refer to Chart A2-7B Fuel System Pressure Check for fuel pressure check procedure. Chart A2-7B Fuel System Pressure Check

For additional checks, refer to On-Board Diagnostic System Check. Testing and Inspection

NOTICE: If test shows excessive NOx, check items which cause vehicle to run LEAN or too hot.

CHECK: EVAP canister and the Tank Pressure Control (TPC) valve for proper operation.

IGNITION SYSTEM
CHECK: For incorrect timing or excessive advance.
CHECK: Ignition system.
CHECK: Spark plugs, plug wires, and ignition components.

ADDITIONAL CHECKS
CHECK: For vacuum leaks.
CHECK: For lead contamination of three way catalytic converter (look for the removal of fuel filler neck restrictor).
CHECK: Carbon buildup. Remove carbon with top engine cleaner. Follow instructions on can.
CHECK: EGR valve for not opening.
CHECK: PCV valve for being plugged, stuck, or blocked PCV valve hose, or fuel in the crankcase.