COMMON SIGNS OF A DIRTY AIR FILTER
A car engine combines air and gasoline in the combustion chamber to create power. This air reaches the engine through an air filter that prevents road debris, dirt, bugs, and other contaminants that can damage the engine. At the same time, the air filter must allow enough air to reach the engine so that it can run efficiently. Over time, the air filter can get dirty and clogged, and the lack of air can affect your car's overall performance.
Most auto companies recommend changing the air filter every 10,000 to 15,000 miles, or every 12 months. However, if you typically drive in dusty or rural areas like Scottsdale, Arizona, or San Antonio, Texas, you may want to have your mechanic check and change it more frequently, such as every 6,000 miles. Driving in crowded areas where there is a lot of traffic - including Los Angeles and Washington DC - and you have to stop and start more often also requires you to replace the air filter more frequently.
Take note of these symptoms that indicate your air filter needs to be replaced:
Reduced Fuel Economy:
Your engine compensates for low amounts of oxygen by consuming more fuel to produce sufficient power. So, if you notice that your fuel consumption is dropping, it could indicate that the air filter needs to be replaced. However, this is only true for carbureted cars, most of which were manufactured before 1980. Newer cars with injection engines have on-board computers that calculate the amount of air entering the engine and adjust the flow rate accordingly. Therefore, the cleanliness of the air filter on newer cars should not significantly affect fuel economy.
Restricted air supply from a dirty air filter causes unburned fuel to exit as soot residue. This soot builds up on the spark plug, which in turn cannot provide the spark needed to burn off the air-fuel mixture. You will notice that the engine does not start easily, misfires, or jerks suddenly.
Unusual Engine Sounds:
Under normal circumstances, when your car is stationary with the engine running, you should feel the smooth rotation of the engine in the form of subtle vibrations. If you notice that your car is vibrating excessively or hears a coughing or clicking noise, it is often due to a dirty or damaged spark plug resulting from a clogged air filter.
Check that the Engine Light Comes On:
Many modern engines suck in about 10,000 gallons of air for every gallon of fuel burned in the combustion cycle. The inadequate air supply can cause carbon deposits to build up in the engine, which could trigger the Check Engine Light to come on. If this happens, have your mechanic check the air filter among other diagnoses.
The Air Filter Looks Dirty:
A clean air filter appears white or off-white, but because it accumulates dust and dirt, it will look darker. However, very often the internal layers of filter paper inside the air filter can contain dust and debris that is not visible even in bright light. Therefore, it is essential that your mechanic check the air filter when you take the car for service. Be sure to follow the manufacturer's instructions regarding the replacement.
If your car is not responding properly or if you notice sudden movements when you step on the accelerator, it may be a sign that your engine is not getting all the air it needs. Replacing your air filter can improve acceleration or horsepower by up to 11%.
Black Smoke or Flames Coming out of the Exhaust:
The inadequate air supply can cause some of the fuel not to burn completely in the combustion cycle. This unburnt fuel then exits the car through the exhaust pipe. If you see black smoke coming from your exhaust pipe, have your mechanic replace or clean the air filter. You might also hear popping sounds or see a flame at the end of the exhaust. This happens when the heat in the exhaust system ignites unburned fuel near the exhaust pipe. This is a potentially dangerous condition and should be diagnosed immediately.
The Smell of Gasoline When Starting the Car:
If there is not enough oxygen in the carburetor or fuel ejection system when you start the car, the excess unburnt fuel comes out of the car through the exhaust pipe. This is when you will smell the gasoline and know it is time to replace the air filter.