Catalytic Converter: Description and Operation

Closed Loop Fuel Injection System:

Closed Loop Fuel Injection System

The system is controlled electronically by an oxygen sensor placed in the exhaust pipe ahead of the catalytic converter. The catalytic converter consists of a ceramic or metal backing coated with a porous layer containing the catalytic materials rhodium and either platinum or palladium.

The catalytic converter has a high conversion efficiency within a very narrow range. If the fuel-air mixture is not kept within this range, one or more gases will inevitably exceed the permitted limits. A closed loop fuel injection system ensures that the fuel-air mixture is completely correct.

Assuming that the closed loop fuel injection system gives an optimal fuel-air mixture ratio, the catalytic converter reduces the nitrous oxides (NOx) and oxidizes the carbon monoxide (CO) and hydrocarbons (HC). The end products are carbon dioxide (C02), water (H20) and nitrogen (N2).

In order for the catalytic converter to reduce the emissions, the car must be run on unleaded petrol only. This is because lead destroys the active components of the three-way catalytic converter.