Emission Control Systems: Description and Operation

The system is electronically controlled by an oxygen sensor located in the exhaust pipe in front of the three-way catalytic converter.

The three-way catalytic converter contains an insert of ceramic or corrugated thin steel plate whose walls are coated with a catalytic material, Platinum and Rhodium.

The three-way catalytic converter has a high conversion rate within very specific limits. If the fuel/air mixture is not kept within it's range, one or more of the gasses will inevitably exceed the permitted level. A closed loop multiport injection system ensures that the fuel/air mixture is always correct.

Provided that the closed loop fuel injection system gives an optimal fuel/air ratio, where carbon monoxide (CO) and hydrocarbons (HC) are oxidized, the three-way catalytic converter can also reduce the quantity of oxides of nitrogen (NOx). The final products are then carbon dioxide (CO2), water (H2O) and nitrogen gas (N2).

In order for the catalyst to reduce the emissionss, it is essential that the car is only filled with unleaded gasoline. This is because lead destroys the active components of the three-way catalytic converter.