An internal combustion engine needs to mix approximately 10,000 liters of air with each liter of fuel to run. Air enters the engine through the air filter, and without a proper air intake, the fuel mixture will be too rich in fuel, so it will not burn properly and the engine will be deprived of the oxygen it needs. Most manufacturers recommend replacing the air filter every 12,000 miles (approximately 19,000 km) or every 12 months, whichever comes first. However, if you live in an agricultural area or in any area with a lot of dust or impurities in the air, you should consider replacing your air cleaner more often.
Inadequate air supply can cause carbon deposits to build up on the engine, which will eventually activate the engine check light. If the light comes on, check the air filter to see if it needs to be replaced before performing other diagnostics. A dirty air filter reduces the amount of air supplied to the engine, resulting in incomplete combustion and misfire of the engine. This can cause an increase in unburned fuel that turns into soot residue, which can soil the spark plugs and cause a misfire.
Engine misfire can significantly increase vehicle emissions. Soot can build up on spark plug tips, making them unable to produce a proper spark. In return, the car may move abruptly, idle, and in some circumstances, the engine may fail. With every revolution, the engine needs to breathe; a clogged air filter slows airflow.
As the air filter picks up more debris, the airflow slows down even more, making it difficult for the engine to breathe and generate power and torque. If you're an energetic driver, a filled air filter will drag you down. Most vehicles also have a cabin air filter that is used to clean the air entering the interior of the car, but it has a different maintenance program than an engine air filter. Contaminated air filters provide insufficient air, so the engine ends up consuming more fuel to compensate for excess.
If you can't add a new air filter right away, if you're off the road or you're running away, you can get excess dust out, but never use compressed air to clean a dirty air filter. Contrary to intuition, dirty air filters do not affect the fuel economy or emissions of computer-controlled gasoline and diesel engines as long as they were built after the introduction of closed-loop oxygen sensor feedback systems. Older model cars that do not include an airflow sensor of any kind have difficulty dealing with air volumes as they can easily alter their fuel ratios, making them very vulnerable to the effects of a clogged air filter. Inspecting a dirty air filter and replacing one is arguably the easiest maintenance task one can do for your car.
If you smell gasoline when you start the car, it's because not enough air enters the fuel injection system and excess unburned fuel comes out of the car through the exhaust pipe (hence the smell). Over time, the engine air filter can become dirty and lose its ability to filter air entering the engine. If this happens, it can detach from its seals and even disintegrate - spelling disaster for your engine. Replacing a dirty engine air filter with a new one can improve engine acceleration and reduce vehicle emissions.
To learn more about how a dirty air filter can cause engine problems and how to prevent them from occurring in your vehicle, talk to an expert at your local NAPA AUTO PARTS store.