Excessive Exhaust Emissions (Odors)

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.

IMPORTANT PRELIMINARY CHECKS
Before using this section you should have performed the "On-Board Diagnostic System Check" - Powertrain/On-Board Diagnostic System Check and determined that:
1. The control module and MIL (Service Engine Soon) are operating correctly.
2. There are no diagnostic trouble codes stored, or there is a diagnostic code but no MIL (Service Engine Soon).
^ Several of the following symptom procedures call for a careful visual/physical check. The importance of visual/physical checks cannot be over stressed. because they can lead to correcting a problem without further checks and can save valuable time.

VISUAL / PHYSICAL CHECK
This check should include:
^ Control module grounds for being clean, tight, and in their proper location.
^ Vacuum hoses for splits, kinks and proper connections, as shown on "Vehicle Emission Control Information" label Check thoroughly for any type of leak or restriction.
^ Air leaks at all mounting areas of the intake manifold sealing surfaces.
^ Ignition wires for cracking, hardness, proper routing, or carbon tracking.
^ Wiring for proper connections, pinches, and cuts.
^ The following symptom charts contain groups of possible causes for each symptom and cover several engines. These procedures are not necessarily meant to be done in consecutive order. If Tech 1 scan tool readings do not indicate the problems, then proceed in a logical order, easiest to check or most likely cause first. To determine if a particular system or component is used on a specific vehicle, refer to the "Electronic/Powertrain Control Module (ECM/PCM)" Wiring Diagrams for application. Electronic/Powertrain Control Module (ECM/PCM)

^ Perform "On-Board Diagnostic System Check." - Powertrain/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 "DTC 45 Diagnostic Aids". DTC 45
^ If EMISSION TEST shows excessive NOx, check items which cause engine to operate LEAN or too hot.

SENSORS
^ CHECK: 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
^ CHECK: If the system is running rich, (long term fuel trim less than 115), refer to "DTC 45 Diagnostic Aids" DTC 45 or if the system is running lean, (long term fuel trim greater than 150), refer to "DTC 44 Diagnostic Aids". DTC 44
^ CHECK: For properly installed fuel cap.
^ CHECK: Fuel pressure. Refer to "CHART A-6". Related Tests, Information and Procedures
^ CHECK: If test shows excessive NOx, check items which cause engine to operate LEAN or too hot.
^ CHECK: Canister for fuel loading. Testing and Inspection

IGNITION SYSTEM
^ CHECK: Ignition system, incorrect timing, or excessive advance.
^ 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 buildup. Remove carbon with top engine cleaner. Follow instructions on can.
^ CHECK: EGR valve for not opening. System Diagnosis - Exhaust Gas Recirculation (EGR) System
^ CHECK: Crankcase ventilation valve for being plugged, stuck, or blocked [1][2]PCV hose.