The car air filter is used to filter the air that enters the engine, to filter out the dust and debris particles in the air, and to ensure that sufficient clean and dry air enters the cylinder. The engine suck in a lot of air during the working process. The air contains many dust particles. If it is not filtered by the air filter, it will cause accelerated wear of the piston group and cylinder. If larger particles enter between the piston and the cylinder, it will cause the cylinder to pull.