What Will Happen if the Air Filter Is Stopped Up on Your Car?

Most air filters are easily replaced.

An air filter is seldom suspected as the cause of a breakdown, but it should not be ruled out without investigation. A stalled vehicle that bears a sparkling new air filter may be suffering from symptoms left behind by the old, stopped-up filter. A lack of understanding or appreciation may lead to neglect of the filter, or an impulsive drive across an open field might pack the filter with flora and fauna, like seeds and insects. Symptoms may develop slowly and faintly at first, but continued use of a clogged air filter will make itself known, sooner or later.

Slow Starts

The first symptoms you may notice could become evident by a lack of acceleration. Speeds normally relied upon to climb that freeway ramp on your daily commute may not come so readily. Realization that your car or truck is taking more time to travel the same distance is good reason to inspect the filter. The decrease in power might require exaggerated accelerator movements, or force the need for downshifts not previously experienced.

Slow Motion

The internal combustion engine in your vehicle is primarily an air pump. It sucks in huge volumes of air, mixes in a little fuel and converts the blend into power. Combustion byproducts go out the tailpipe, after some emission control devices eliminate solids and gases. A clogged air filter causes the mixture to become overloaded with fuel. The rich mixture results in sooty deposits from unburned fuel getting in and on emission control devices. The devices become clogged or "blinded" and engine performance fades quickly.

Short Stops

A clogged air filter reduces the engine's ability to produce vacuum, and crankcase fumes and liquids may build up on the air filter element. The vapors can wick through the filter element and adhere to parts in the air intake system. Sensors may be affected, but throttle plate gaps and other idle air passages evince contamination first by causing stalls at idle speeds. A car that stalls at every stop sign, may only need a fresh air filter and a throttle body cleaning.

Small Change

Air filter designs vary widely in modern engine compartments, and replacement costs may seem exorbitant for a particular vehicle. Putting off the investment may seem like a small matter, until reliability and performance is considered. You can shake sand, dust and insects off the filter element, if no other defects prevent continued use. However, a new filter allows better air flow than a filter that has seen better days.

References

• Electric and Electronic Systems for Automobiles and Trucks; Robert N. Brady

Resources

• Edmunds: Suck-Squeeze-Bang-Blow