A car engine starts thanks to the ignition system. This is the unit that supplies the energy to get the motor going. The ignition system begins with a key, which you insert and turn, and ends with a spark that ignites combustion in the cylinders. This combustion is what starts the engine. It is important to note that everything up until the moment of combustion in the car cylinders is part of the ignition system.

 

The battery provides a vehicle with the twelve volts necessary to power things when the car isn’t actually running. For startup purposes, the battery is responsible for sending electricity to the starter, the coil and the distributor, as well as a hot wire to the alternator so that things can recharge after starting. If the battery is too weak to turn the starter, starting the vehicle becomes difficult or impossible. A good alternator combined with a good battery will keep things at above twelve volts. It should be thirteen to fifteen when the car is running.

When you turn the ignition key in your car to the “On” or “ACC” position, it sends electricity to the coil and the distributor, which will send spark to the plugs once the engine is turned over. When the ignition key is turned just a bit more, it sends twelve volts to the starter, which has gears that mesh with the engine and ultimately turn it over. Most engines don’t need to turn very fast in order to start. Just a few good revolutions are all it takes.

 

Of course, your engine uses fuel of some sort. While the starter turns the engine over, a small amount of fuel is fed into it by either the carburettor or the fuel injection system. On a carburetted engine, it may be necessary to “pump” the accelerator pedal a few times in order to get sufficient fuel into the engine. On fuel injected cars, the entire system is pressurized and most likely uses an electric fuel pump, so it’s more of a “hands free” startup.

 

When you start the car by turning the key, several parts are set into motion. First the starter motor comes to life, and then the engine begins to turn and the spark plugs fire. When the key is turned, the starter motor “turns the engine over,” which means it turns the crankshaft which in turn gets the pistons moving in the cylinders. This starts the engine cycle. Air and fuel is drawn into the cylinders, it is compressed and the then the spark plugs fire. This begins combustion.

 

When you first turn the key you may notice your engine makes a grating, heaving sound. This is the sound of crank shaft turning and pistons moving, which begins the engine cycle and compression. Without this, the car would not be able to start the chain reaction of combustion that keeps it running under its own power. If your car doesn’t start there may be something getting in the way of this process, like no fuel, low battery or a clog in the engine system.