During which stroke does the spark plug ignite the gas/air mixture?

During the power stroke, the spark plug ignites the gas/air mixture that has been compressed in the combustion chamber. This ignition is critical because it creates an explosion that forces the piston down, generating power to turn the crankshaft, which ultimately propels the vehicle.

In a typical four-stroke engine cycle, the process starts with the intake stroke, where the piston moves down and air and fuel are drawn into the cylinder. Next is the compression stroke, where the piston moves back up, compressing the gas/air mixture to prepare for ignition. The spark plug only fires during the power stroke, which occurs after the mixture has been compressed and is ready for combustion. Following the power stroke, the exhaust stroke expels the spent gases from the cylinder, completing the cycle. Thus, it is during the power stroke that the ignition of the gas/air mixture occurs, leading to the engine's functioning and generating power.