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 Perform idle speed adjustment. Curb Idle Speed Adjustment

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

Fuel metering Check air/fuel ratio. Adjustments
Check fuel pressure (check fuel line and vapor return hose).

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 for excessive alcohol content. Alcohol In Fuel Test
Recommend higher grade fuel
Drain fuel tank and add clean fuel