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 on-board diagnostic system check.

- IF EMISSION TEST shows excessive CO and hydrocarbon check items which cause car to run RICH (Long Term Fuel Trim less than 118), refer to "Diagnostic Aids" for diagnostic trouble code (DTC) 45.

- If EMISSION TEST shows excessive NOx, check items which cause car to run lean or too hot.


COOLING SYSTEM

- If the "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 open) or for wrong heat range.

- CHECK: Cooling fan operation.


FUEL SYSTEM

- NOTICE: If the system is running rich (L.T. Fuel Trim near 118), refer to "Diagnostic Aids" for DTC 45.

- If the system is running lean (L.T. Fuel Trim near 142) refer to "Diagnostic Aids" for DTC 44.

- CHECK: For properly installed fuel cap.

- CHECK: Fuel pressure. Use CHART A-7.

- CHECK: Canister for fuel loading. Refer to Evaporative Emission System.


IGNITION SYSTEM

- CHECK: Ignition timing. Refer to "Vehicle Emission Control Information" label.

- CHECK: Spark plugs, plug wires, and ignition components.


ADDITIONAL CHECKS

- CHECK: For vacuum leaks.

- CHECK: Exhaust gas recirculation valve for not opening. Use CHART C-7.

- CHECK: For lead contamination of three way 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: PCV valve for being plugged, stuck or blocked PCV hose or fuel in the crankcase.