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Posted by Anderson on Oct 15, 2015

Why Do Some Cars Fail An Emissions Test?

Failing an emissions test can be frustrating. It can cost you not just time, but also resources in getting things fixed. That’s why people are so driven to find the car that matches power with eco-friendliness. Some Volkswagen cars, for instance, promise the power a diesel engine can give while giving off fewer pollutants that may harm the environment.

But, according to the website of lawyers of The Driscoll Firm, the auto company has just recently been involved in an emission fraud controversy that sent ripples throughout the global car economy. According the firm’s website, Volkswagen was found to deliberately sell cars equipped with software designed to defeat emissions test. But why do cars fail an emissions test in the first place?

Here are just some of the many reasons:

You have leaky injectors

For gasoline engines, an air injector system introduces air to the compression chamber in conjunction with the gasoline. This air-gasoline mixture will then be compressed and ignited to create combustion gases that would push the piston down. If the intake valve that injects air into the chamber is faulty, chances are you will have a rich fuel mixture. This richness may result in higher levels of unburned fuel, causing your car to fail the test.

You have a faulty air injection system

Air injection system, commonly known as a smog or pollution pump, was introduced in 1966 as a strategy to control vehicle emissions. It works by injecting fresh air into the exhaust manifold or exhaust ports. The oxygen introduced in the engine’s exhaust system will continue to burn (or more scientifically, oxidize) the unburned and partially burned fuel as it passes through the exhaust and into the tailpipe. As a result, less unburned fuel goes out of your car, and you are more likely to pass the emissions test.

You have defective spark plugs

If your spark plugs are defective, chances are your engine doesn’t burn gasoline as effective as it should be. Before getting your car tested, check first if your spark plugs are worn out or your spark plug wires are working properly. However, defective spark plugs should never be the reason why a diesel car would fail the test, because diesel engines do not use spark plugs to start the process of combustion.

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