Reducing emissions, dirty or damaged air filters can reduce airflow to the engine and change the car's air-fuel balance. This imbalance can cause the engine to fail or idle abruptly, increase engine depositions, and trigger the “Engine Service” light. Replacing your engine air filter is an often overlooked maintenance item, but a dirty air filter can have a negative effect on your car's performance. The frequency with which the engine air filter will need to be replaced varies depending on the vehicle brand. Maintenance schedules for different vehicle brands differ in how often the air filter needs to be changed.
On most Chevrolet engines, for example, the recommended change interval is every 45,000 miles, but Ford says it should be done every 30,000 miles on many of its engines. Hyundai also says every 30,000 miles, but shortens it to 15,000 for “severe” driving conditions, including heavy traffic in hot climates and frequent driving on unpaved roads or dusty conditions. These rules will apply to other brands as well. If you drive in such conditions, it may be necessary to replace the air filter before the recommended interval. You may be able to tell when a filter needs to be replaced just by looking at it.
If you find black areas in the section where outside air enters, it may be time to change it. The good news is that the air filters on most engines are easy to access and you can check the location in your owner's manual if you need help. If you can't tell by looking, but it's been more than three years or 30,000 miles, you should probably buy a new one (especially if you can save money doing it yourself). However, you should be careful if every time you change the oil, the repair shop says you also need a new air filter. We expect drivers, in most cases, to spend more than a year, at least, and probably more than two years between air filter changes, depending on conditions and mileage. You'll get about 1BHP more from a good quality filter.
But unless you're the princess who slept in the pea, you won't notice. What better quality filters DO have is that they take longer to clog. So, they don't really GIVE you more power; they're better at AVOIDING energy loss once you've driven a couple of thousand miles. I think it depends on the application. I paid good money for a K&N air filter for my old traveler, an 18-year-old Subaru 4-cylinder.
After installation, I heard a pretty clean grunt noise from the engine when accelerating, but the idle and mileage and gasoline performance were the same. On the other hand, a K&N air filter installed on my Kawasaki Concours not only gave me that cold grunt noise when accelerating but I noticed a smoother idle and a small increase in top speed performance above 7,000 rpm. So there you go; I think they're worth the money and time spent cleaning them every few thousand miles if used in a performance application. But for a normal old car, the standard cheap paper filter is the way to go. An air cleaner is one of the most economical maintenance components to replace and can be done by doing it yourself. The cabin air filter should also be changed periodically but at a different time than the engine air cleaner.
The test simulated clogging by covering air filters with shop cloths severely restricting airflow and concluded that the reduction in flow “did not have a significant effect on fuel economy” using federal fuel economy test procedures. A clean air filter will help your engine perform better; on newer cars it can increase acceleration by up to 11%, and on older cars it can improve mileage by up to 14%. If you have allergies or respiratory sensitivity or live in an area with bad pollen or excessive smog then you may need to replace your cabin air filter more often. If a clogged filter reduces the amount of air entering then those controls reduce the amount of fuel accordingly to maintain the proper mix of driving emissions and other factors. The cooler air outside of the engine compartment is denser than warm air inside of it which is heated by internal combustion of the engine and other movement mechanisms that generate heat through friction. As its name suggests this air filter is located inside of an engine to keep harmful debris out of this system. For some people adding a high-performance air filter is not a necessity but something worth buying simply because they are interested in modifying their vehicle.
By providing clean airflow to an engine an air filter ensures that it receives correct amount of air needed to operate at its maximum level. However engines rely on clean good airflow to produce power and rapid acceleration so restricting amount of air will definitely affect performance. Cabin air filters tend to get dirty faster than engine filters and need to be replaced more often. Several aftermarket filters promise to increase power and acceleration by creating better airflow. For every gallon of fuel burned an engine consumes up to 10 000 gallons of air so it's easy to understand how important clean filter is for proper operation of car. Air filter replacement can be part of general tuning service that will help get better mileage and performance out of vehicle.