Ignition Coils and their Importance
In a car engine, ignition coils are the components that amplify voltage from the charging system (battery and alternator) and deliver it to the spark plugs. It may differ from car to car, but there is a separate ignition coil for each spark plug, while others may have multiple plugs for a single coil.
Because of the low voltage produced by the battery of a vehicle, ignition coils are necessary to ignite the fuel and start the engine. Because they are a transformer, ignition coils convert the low voltage from the battery into a high voltage current thus increasing the performance of the car.
Ignition Coil Differences
Modern vehicles commonly use coil-on-plug systems, with the ignition coil directly attached to each spark plug (see below).
In some vehicles, the coils are located on the cam/rocker cover which is on the uppermost of the engine. Fewer cars have two ignition coils per two spark plugs or two ignition cassettes that power half each spark plug.
Common Causes of Ignition Coil Issues
Many of these coils were new when they were made, but the reasons they fail are often due to wear and tear - thousands of miles of vibrations and high temperatures can cause irreversible internal damage.
Moisture damage is another prevalent problem. Typically, it occurs as a result of engine oil leaks, but it also occurs as a result of other leaks and condensation. Over time, the valve cover between the ignition coils and spark plugs can loosen leading to the oil leak dripping in and causing malfunctions. Water intrusion is highly unlikely but cannot be completely ruled out. In rare cases, some vehicle’s A/C condensation can lead to build up of moisture in the spark plugs.
Excessively worn-down spark plugs can cause the ignition coils to undergo additional stress, causing premature failure. This is due to the widening of the spark plug gap as spark plugs wear out. To compensate for this, the ignition coil will need to supply a higher voltage to overcome this gap. An ignition coil that is continuously subjected to higher voltages will wear out prematurely over time.
Spark Plugs and Ignition Coils
The ignition coil and the spark plug go hand in hand. In the event of one failing, the other will not be able to function.
Together with ignition coils, spark plugs are one of the most common parts to replace. It is common for worn-down plugs to cause unnecessary load on the coils, since replacing both spark plugs and coils happen at the same time. It would be best to replace both components simultaneously if your ignition coils failed due to worn-out spark plugs.
A spark plug wire that appears old, worn, or damaged should be replaced if it is in contact with the ignition or spark plug. To prevent the problem from recurring in the future, the moisture source (for example, an oil leak) should be addressed along with the ignition coil replacement.
Call a mechanic as soon as you notice a problem with your ignition coil. One of the first questions you should ask your mechanic, “Is it necessary to replace my ignition coils AND spark plugs?”. The mechanic will be able to determine if it is necessary to replace both your ignition coil and spark plug.