The following is a simple look at the emissions control system of your personal automobile, which is something many don’t understand.
First, lets talk about why there is a need to control the emissions output of vehicles with gasoline or diesel powered engines. Nitrogen oxide and carbon monoxide are byproducts of fuels refined from petroleum burned to power the engine of a car. When these gasses are released into the atmosphere of the earth, they have very damaging and irreversible effects. The harmful gasses entering the atmosphere are not all created from the burning action of petroleum-based fossil fuels; hydrocarbons are a harmful gas emitted by the vaporization of the fuel stored in the fuel tank and from the crankcase.
In 1977, the U.S. government passed the clean air act setting limits to how much of each pollutant was allowed to be released by a car. Automobile manufacturers responded by adding pollution control devices to cars as standard equipment. In 1981, the first of a new generation of self-adjusting engines controlled by computers called feedback fuel control systems was introduced to the market place. Oxygen sensors were installed in the exhaust system to measure the fuel content being expelled with the exhaust gasses. The computer would then adjust the fuel to air mixture to help compensate for the unused fuel loss.
With the progressive maturity of the emissions control system computers used in automobiles, they began to be used to adjust the ignition spark timing on the fly as well as the other emissions control system equipment.
The emissions control system of your car consists of no less than five different standard equipments parts controlling five different emissions contributing factors. These five standard emissions control equipment parts are: catalytic converter, PCV valve, EGR valve, evaporative controls and air injection. The catalytic converter may be the single most important part of the emissions control system.
The catalytic converter is part of the exhaust system installed before the muffler.
Inside of the catalytic converter are pellets or a honeycomb chamber made of platinum or palladium. The platinum or palladium acts as catalyst, speeding up the chemical process of the hydrocarbons and carbon monoxide being oxidized and converted into carbon dioxide and H2O (water). When this process takes place, heat is produced. The more pollutants in the exhaust, the more heat produced. Excessive amounts of heat with cause the catalytic converter to destroy itself. Because lead will coat the platinum or palladium, rendering its efficiency to an almost useless level, all fuels in the USA are now unleaded.