CORRECT OPERATION

The catalytic converter operates at extremely high internal temperature (about 1,500° F.) to finish burning the hydrocarbons (HC) or carbon monoxide (CO) that remain in the exhaust gas after normal combustion. The burning process converts most of these pollutants to water and carbon dioxide. Usually rhodium, palladium, platinum, or some combination is used as the catalyst. Some catalytic converters also burn oxides of nitrogen.

Sometimes, cars equipped with catalytic converters will emit a sulfur-based rotten egg odor. The smell is actually hydrogen disulfide. Sulfur contained in the gasoline eventually becomes part of the exhaust. When the exhaust is treated by the nitrous-oxide section of a three-way converter, the pungent smelling gas is formed. The more oxygen the converter contains from the air injection system, the stronger the smell. The smell signifies abnormal operation.

If the odor is present in your vehicle and must be eliminated, consider taking the following steps:

• Try another brand gasoline that may have a lower sulfur content.
• Avoid harsh accelerations. Most fuel in these situations remains unburned and eventually makes direct contact with converter elements. The sulfur odor then becomes stronger.
• Have the ignition timing or fuel/air mixture adjusted if necessary. The idea is to completely burn the fuel injected or drawn into the cylinders so no raw fuel exits through the exhaust and reacts with the catalytic converter.

SYSTEMS
CATALYTIC CONVERTER
PROPER CARE
VARIATIONS