System Overview

Generic Catalyst and Exhaust System:

PURPOSE
The catalytic converter and exhaust systems work together to control the release of harmful engine exhaust emissions into the atmosphere. The engine exhaust gas consists mainly of Nitrogen (N), Carbon Dioxide (CO2) and Water Vapor (H2O). However, it also contains Carbon Monoxide (CO), Oxides of Nitrogen (NOx), Hydrogen (H), and various unburned Hydrocarbons (HC). Carbon monoxide, oxides of nitrogen, and hydrocarbons are major air pollutants, and their emission into the atmosphere must be controlled.

COMPONENTS
The exhaust system generally consists of an exhaust manifold, front exhaust pipe, Upstream Heated Oxygen Sensor (HO2S), rear exhaust pipe, Downstream HO2S, a muffler and an exhaust tailpipe. The catalytic converter is placed between the front and rear exhaust pipes. Catalytic converter efficiency is monitored by the On Board Diagnostic (OBD II) system.

OPERATION
A catalyst is a material that remains unchanged when it initiates and increases the speed of a chemical reaction. A catalyst will also enable a chemical reaction to occur at a lower temperature. The concentration of exhaust gas products released to the atmosphere must be controlled. The catalytic converter assists in this task. It contains a catalyst in the form of a specially treated honeycomb structure saturated with catalytically active precious metals. As the exhaust gases come in contact with the catalyst, they are changed into mostly harmless products. The catalyst initiates and speeds up heat producing chemical reactions of the exhaust gas components so they are used up as much as possible.