An ignition coil is a source of a high-voltage needed to produce a spark that starts the combustion process in a cylinder. Ignition coils usually fail as a result of wear. They need replacing when the engine's operation becomes unstable, i.e. its speed fluctuates, there is a noticeable decrease in power, you notice acceleration problems or an unusual colour of the exhaust fumes. A faulty coil may even disable the engine.
What is the role of the ignition system?
The ignition system of the petrol engine generates a high voltage and sends it in the right moment to a spark plug, where a spark is generated in the gap between the plug's electrodes, initiating the process of combustion of the fuel-air mixture in the engine chamber.
What is the ignition coil?
It is a source of high voltage. It transforms a voltage of 12 V inside the car's electrical system into a voltage of several thousand volts. The coil is comprised of a copper winding. A low-voltage flows trough the primary winding, inducing, in the secondary winding, a voltage required to generate a spark powerful enough to cause ignition.
How is the ignition coil replaced?
The coil winding gradually burns out and eventually needs replacing. The replacement process is rather simple and requires disconnecting the cable powering the coil and the high voltage cable coming out of it. Next, the coil must be removed from its mounting. A new coil is fitted in the reverse order.
What to keep in mind?
The ignition system should be handled with particular care to avoid a high-voltage electric shock. Remember to remove the key from the ignition before you get down to work.
After fitting a new coil, turn on the engine to check if the ignition system works properly. Some cars must be connected to a diagnostic computer to cancel error codes resulting from an ignition coil failure.