Auto Emissions Testing

When your vehicle fails an auto emissions test due to high levels of hydrocarbons (HC), frustration may set in. It helps to understand why states regulate hydrocarbon emissions and how to correct problems.

Reason for Regulation
Car emissions and other sources emit hydrocarbons into the air, according to the U.S. Environmental Protection Agency, and contribute to ozone that can cause eye and lung irritation. Many states or high population areas mandate smog check HC tests every couple of years. During the test, the technician usually checks for carbon monoxide and nitric oxide. The technician inserts a probe in the tailpipe and measures the parts per million of hydrocarbon molecules (HC PPM).

Combustion Process
The combustion process ignites a mixture of air and fuel. If the concentration of un-burnt fuel is higher than set standards, the vehicle "fails" on that criterion. Often the testing facility will give a booklet explaining repairs that can help the vehicle pass a re-inspection.

Causes and Solutions
Several mechanical deficiencies can cause high HC levels. The Virginia Department of Environmental Quality describes Types of Emissions Inspection Failures on their website. Ignition problems like faulty spark plugs and wires can create high HC levels. Ignition timing can impact HC as well. If the spark is occurring too soon or late after the injection of fuel, the un-burnt fuel releases HC into the air. A worn oxygen sensor can cause a rich fuel mixture. An air filter clogged by dirt can lead to a rich fuel mixture as well. Sometimes dirty engine oil leads to a high HC reading. A properly working catalytic converter reduces HC and other harmful exhaust products. The tester may also check the gas cap for leaks of fuel vapor into the air.

If your vehicle fails the emission test due to HC levels, don't despair. If the car needs a tune-up, do that first. For expert diagnosis, take it to a mechanic that specializes in emissions repair. After successful repair and re-inspection of the vehicle, enjoy knowing your car pollutes less and complies with legal requirements.

Auto Emissions Testing on Kit Cars and Modified Vehicles

Almost all vehicles are subjected to auto emissions testing. This includes both kit vehicles and modified vehicles.

A kit car is defined as an automobile that is made from parts that are assembled by the owner. On the other hand, a modified vehicle is a type of vehicle that has been upgraded with components and aftermarket parts to enhance the performance of the vehicle. For kit cars, emissions standard requirements are based on the year of the engine and not the year of the body of the car.

Certain guidelines need to be followed for a vehicle to pass its emissions testing. In some cases, emissions testing is required for a license or to register the car. Specialty vehicles like classic or antique cars, modified, and kit cars are still required to undergo an auto emissions test.

Auto Emissions Testing in Some States
Generally, each state either follows the EPA nationwide regulations regarding auto emissions testing or adapts the CARB guidelines. However, there are some states that do not have a safety inspection test requirement or only require emissions testing in some parts of the states.

California provides registration of new kit cars with a title dated according to the year the kit car most resembles. However, there are just 500 such tags available each year. Otherwise, all vehicles must undergo emissions testing including modified vehicles and kit cars.

In Ohio, auto emissions testing is done depending on the type of engine the car has. Ohio has guidelines for engine-switched vehicles, rebuilt vehicles, gray market vehicles, self-assembled vehicles, and kit cars. Kit cars are tested according to the titled year of the engine. It is important to remember, that determining the engine year is the sole responsibility of the car owner. It is also important to note that proof, like a letter from the manufacturer, of the engine or the dealer is needed. Also, a form is provided that allows the vehicle to be tested under the proper standards for the specific engine year if the engine year is within the scope of the emissions testing program.

Some states exempt kit cars and modified vehicles from emissions testing. In Pennsylvania, vehicles registered as classics, antiques, street rods, collectibles, or specially constructed are exempt from undergoing an emissions inspection. However, all cars in Pennsylvania need to undergo a safety inspection every year.

Related Questions and Answers

Are Certain Engine Types more Prone to Failing a Vehicle Emission Test?

Fuel injection system engines are less likely to fail vehicle emission test systems simply because they are very well controlled. Emissions tests are a very important factor in the approval of a car for use on the market. Injection systems spray the exact amount of gasoline into the system, reducing heat, gas mileage and pollution. Multi-point injection systems, direct and indirect systems, are much better because the system reduces the dangerous chemicals that are released into the atmosphere. The system also ensures that the engine is far cleaner due to the reduced emissions.

What is the Role of Hydrocarbons in a Failed Emissions Test?

If your car has failed an emissions test, due to elevated hydrocarbons, then there are a few things you have to know. Elevated hydrocarbons are usually due to ignition misfires and because of fouled spark plug. There is also a chance that a burned exhaust valve will blow out extra hydrocarbons through the tailpipe. Internal combustion problems like broken rings, cracked pistons, and worn spare parts will all cause extra hydrocarbons to be formed inside the engine. Although there are many reasons for a failed emissions test, you have to check your car out completely to eliminate the cause. Unless the car passes the emissions test, you will not be allowed to use the car on roads.