Air Filters for Fuel-Injected Engines

One of the most important requirements is a smaller filter size. Round cylindrical filters can clean the air well enough, but they leave too much empty space inside, and they take up room that is already tight under the hood. As a result, manufacturers began making panel-style air filters. These come in square or rectangular shapes. The filter paper is also laid out differently. Instead of being arranged radially, it is folded into a block of ready-made pleats, which creates small pockets. This keeps wasted space to a minimum. Cylindrical filters still exist, but they are only fitted to older designs or to special vehicles that have been tuned and equipped with low-restriction («zero-resistance») filters. No matter what shape a filter has, it should let through no more than 1% of dust. Otherwise, engine wear will come too quickly.

The air filter affects both power and fuel consumption. If a filter is made from unsuitable filter media, it can clog quickly, which causes problems with engine operation. If the air-fuel mixture runs too rich, fuel consumption goes up and the engine performs worse. If the engine starts to feel sluggish, it's time to think about replacing the air filter.

What if you ignore the manufacturer's warnings and the need to replace the filter, and it just keeps on working? In that case, you risk damaging the engine.

1. The engine can fail if the filter uses paper or nonwoven material with oversized pores. Abrasive particles can then get into the engine.

2. Poor-quality paper can tear, letting a large amount of dust into the engine.

3. The filter doesn't seal tightly, so dirty air bypasses the filter element and goes straight into the engine.

To avoid these problems, pay attention to the filter media, because the filter's performance depends on it.

The service life of air filters fitted to popular mass-market cars can be 10,000 to 25,000 kilometers (about 6,000 to 15,500 miles). If the car is driven in very dusty conditions or off-road, the life can be two to three times shorter. In winter, filters usually clog less.

Note that global manufacturers are starting to use the long service interval principle, known as LSI. In this case, the minimum service life is 50,000 kilometers (about 31,000 miles). However, that life can't be reached if the filter uses a pleated element made from ordinary cellulose, because this material can't withstand prolonged loads.