Ignition System

This posting will be the first of a small series of entries that will explain some of the basic systems in a car that are necessary for the car to function normally. It only makes sense to start out with a system that starts an automobile, the ignition system. Many drivers just turn the key and they are on their way, not even thinking about what happens, but there is more that goes on between when the key hits the ignition and when the car actually starts.

Car’s used to have, in most cases, a distributor; when the ignition key was turned, a current ran from the battery, to the ignition coil, then into the distributor. Once the current hit the distributor it would be sent out to all cylinders via the spark plug wires and spark plugs. The coil basically magnified the current from the battery to a much larger current that allowed for enough voltage to start the engine. The distributor cap sent out current to each cylinder. Depending on how many cylinders a car had, the cap would have that many numbers of spots where the current could be sent out. The rotor was a small plastic piece that spun inside the cap, only making one point of contact to the inside wall of the cap. This contact point on the rotor would then touch each point on the cap as it spun to send out the electric current to each different cylinder in a specific order. If this order was wrong for any reason, such as the wires lead to the wrong cylinder, the car wouldn’t start.

Now, many cars are going to distributor-less ignitions where the ECU has total control over the ignition. Each spark plug has its own coil built onto it. This is a much more efficient system because there is no need for a distributor which wears down over time and there is no need for high-voltage spark plug wires which can also break down. This system is completely run by the car’s computer system, thus making the timing even better.
So next time you get in your car think about what happens when you slip your key into the ignition and turn it, it will surprise you how fast all of this happens.