Excessive Exhaust Emissions/Odors

Definition: Vehicle fails an emission test. Vehicle has excessive "rotten egg" smell. Excessive odors do not necessarily indicate excessive emissions.
POSSIBLE CAUSE ACTION
Incorrect idle speed Check minimum throttle body air flow.

Fuel in crankcase Determine cause (flooding, excessive cranking etc.)
Change oil and filter

Fuel metering Check air/fuel ratio, by measuring 02 sensor voltage.
Perform fuel injector cleaning procedure. Fuel Injector Cleaning Procedure
Check fuel pressure.

Faulty fuel cap Replace fuel cap

Lead contamination of catalytic converter Check for missing fill pipe restrictor
Replace catalytic converter

Poor or contaminated fuel Check fuel for excessive alcohol content. Alcohol In Fuel Test
Recommend higher grade fuel
Drain fuel tank and add clean fuel. Fuel Tank Draining Procedure