Though vehicles that have diesel or high-performance engines often emit some strong fumes, this signals a repair issue in the vast majority of automobiles. Abnormal car emissions are generally black or have a rotten egg or gasoline odor.
A faulty fuel pressure regulator can cause strong fumes and black smoke. This part is responsible for maintaining correct fuel pressure; a sudden increase or decrease in fuel pressure, in addition to the fumes, points to this diagnosis.
The purpose of a catalytic converter is to decrease emission toxicity caused by the engine's gasoline burning process. Fumes resembling a rotten egg smell, combined with a decrease in engine power, result from a damaged or contaminated catalytic converter.
If fumes are noticeable in the passenger compartment when the heater or air conditioner is used, then an exhaust system leak is likely. Leaks occur in the manifold gaskets, in the muffler or in the car's undercarriage area.
