The Emissions Control System Of Your Car

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.

Understanding Your Cars Emissions Control System Every car is equipped with an emissions control system that works to minimize the hazardous materials produced by your vehicle during operation. The newer your vehicle the more sophisticated the emissions control system is likely to be, with the older vehicles having very limited systems.

There are several components to your vehicles emissions control system, with each part working together to keep your car operating as cleanly as possible. The first part of the emissions control system is the computer that monitors the content of the exhaust produced by the engine. When fuel to air ratios are incorrect the engine is not working at peak efficiency and will produce a lot more hydrocarbons. The emission control system automatically notes this inefficiency and signals the air and fuel intakes to adjust, correcting any problems in the ratio and resulting in a cleaner and more efficient motor. This is all done in real time as the engine is operating, and the driver and passengers are not aware of these constant adjustments and monitoring of the system.

Another part of the emissions control system in your vehicle is the catalytic converter. This is a part of the exhaust system that is located just before the muffler and acts as an additional area where carbon monoxide can be oxidized into water and carbon dioxide. The catalytic converter is designed like a radiator, with a mesh or honeycomb appearance that allows maximum contact of the exhaust with the platinum or palladium in the catalytic converter, resulting in the oxidation as the hydrocarbons touch the metals. During this oxidation process heat is released, resulting in the catalytic converter becoming very hot, sometimes hot enough to almost glow when the exhaust is very dirty and contains high levels of hydrocarbons. When the catalytic converter overheats, this also sends a signal to the car’s computer through the emission control system, resulting in a signal to the driver by a light on the dash or a computer systems test result in newer models.

The third major components in an emissions control system are the various valves located along the exhaust system and during the actual burning of the fuel through combustion. These valves all have to continue to work at the right time and in the right balance to provide optimum performance for the engine. Drivers of newer model vehicles have the luxury of having these valves monitored by the computer on the vehicle, helping with diagnostic tests when fuel mileage and performance is poor. Some of the new models of vehicles even directly email owners with a performance print out that can be taken to a mechanic or even emailed to your repair shop or dealership to keep on file for your next scheduled tune up.