A dirty engine air filter is removed from a car. It's a large, rectangular metal component caked in dirt and debris.

What Could a Dirty Air Filter Do to Your Engine?

Have you ever wondered what a dirty air filter could do to your engine? Just like you, your engine appreciates breathing clean air, whether it’s a tiny lawnmower motor, a fun dirt-bike engine or that turbocharged monster in your sporty coupe. Let’s take a look at how this lesser-known component plays a huge role in engine health.

Breathe In, Breathe Out

With every intake stroke, the cylinder inhales air, so to speak. Compression or spark combines fuel with oxygen, causing a tiny, controlled explosion. On the exhaust stroke, the cylinder exhales nitrogen, water vapor and carbon dioxide — just like you, only hotter. Your engine has an air filter to keep dust, particles and insects from getting into the cylinders and mucking up the works.

Your engine breathes in a lot of air, and its air filter will eventually fill up with whatever dust and debris are floating around. Over time, a dirty air filter could choke your engine, even damage it. Replace your air filter before that happens.

Heavy debris impedes the flow of air and can even collapse the filter.Choking Performance

With every revolution, your engine needs to breathe; a clogged air filter slows down the flow of air. As the air filter collects more debris, air flow slows further, hindering your engine’s ability to breathe and generate power and torque. If you’re a spirited driver, a stuffed air filter will drag you down.

A Collapsed Lung

Perhaps the worst thing a dirty air filter can do to your car is collapse. If this happens, the air filter can pull away from the seals — even disintegrate — spelling disaster for your engine. An unsealed air filter might as well not even be there, as it allows unfiltered air into the engine. Airborne debris accelerates wear and fouls injectors and sensors, leading to poor compression, oil leaks, oil burning, cylinder misfire or fuel trim problems, causing the check engine light to illuminate.

Filter Replacement Factors

Counterintuitively, dirty air filters don’t affect fuel economy or emissions on computer-controlled gasoline and diesel engines, as long as they were built after the introduction of closed-loop oxygen sensor feedback systems. Modern computer-controlled engines can adjust fuel injection to compensate for a dirty air filter, but carbureted engines depend on air flow for fuel delivery.

A dirty engine air filter needs to be replaced before it damages your engine or slows you down. If you’re experiencing performance problems, replace the air filter as soon as possible. If you can’t immediately add a new air filter, are off-roading or bugging out, you can tap out excess dust, but never use compressed air to clean a dirty air filter. Better yet, carry a spare air filter in your adventure kit.

Check out all the ignition parts & filters available on NAPA Online or trust one of our 16,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on dirty air filter problems, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.

about author

Benjamin Jerew

Ben has been taking things apart since he was 5, and putting them back together again since he was 8. After dabbling in DIY repairs at home and on the farm, he found his calling in the CGCC Automobile Repair program. After he held his ASE CMAT for 10 years, Ben decided he needed a change. Now, he writes on automotive topics across the web and around the world, including new automotive technology, transportation legislation, emissions, fuel economy and auto repair.

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