The ignition system in your car is not just responsible for starting the engine, but keeping it running as well. Gasoline engines rely on the combustion of a mixture of fuel and air, and this combustion is only possible if there is a spark to ignite the gases. Not only that, but in order to achieve optimal performance and keep things running smoothly, the ignition system is responsible for ensuring that the spark plugs go off at precisely the right moment.
An internal combustion engine relies on the combustion of a mixture of fuel and air that moves pistons up and down the combustion chamber to turn cylinders, which then power the rest of the car. The gases are ignited by spark plugs that are located at the top of the chamber.
When the spark is timed properly, the gases will do the most work possible to push the piston back town the length of the combustion chamber. This will distribute the most horsepower and torque to the rest of the engine and allow the vehicle to run more efficiently than if the spark plugs misfire.
Since there is a split-second delay between the spark plug firing and the ignition of the gases, the ideal time for a spark is just before the piston reaches the top of the combustion chamber. This way, when the combustion occurs, the piston will be forced down from the farthest point and generate the most energy. If the spark fires when the piston is at the top of the chamber, the ignited gases will not expand and apply pressure until the piston has already moved back down the chamber, and the opportunity to create more power is lost.
The timing also needs to be adjusted to match the engine speed - it can be advanced when the engine goes faster. Retarding the spark, or adjusting it to occur closer to the piston reaching the top of its stroke, will serve to minimize emissions, and this can occur when the engine does not require maximum power, such as when cruising on the highway. It can also reduce temperatures, which will lead to less nitrogen oxide, a regulated pollutant.