Engine Types, Components, and Maintenance for Students Practice Test 2026 - Free Engine Maintenance Practice Questions and Study Guide

The function of a piston in an engine is primarily to compress the air-fuel mixture within the combustion chamber. The piston moves up and down within the cylinder. When it moves down, it creates a vacuum that draws in the air-fuel mixture during the intake stroke. As the piston then moves up, it compresses this mixture, making it more combustible when ignited. This compression is crucial because it increases the efficiency and power output of the engine when the spark plug ignites the compressed mixture, resulting in a controlled explosion that forces the piston back down, which ultimately generates the power needed for engine operation.

The other options describe functions that are associated with different components of an engine. For example, rotating the crankshaft is a result of the piston's movement but is not the primary function of the piston itself. Regulating fuel flow pertains to systems like fuel injectors or carburetors, while creating electric current is related to the alternator or generator within the vehicle, not the piston.