Ignition Coil

An ignition coil is a mechanical part found only in gasoline-powered vehicles. The ignition coil is a central element in an engine because it controls the operation of the spark plugs. Its purpose is to provide high-voltage current to the spark plugs so that they can produce the spark needed to ignite the air-fuel mixture. Without an ignition coil, or in the event of a failure, the engine will run poorly.

The ignition coil acts as a power distributor in a gasoline engine.  It receives power from the battery, stores it, and then sends a high-voltage current to the engine's spark plugs. With this current, the spark plugs create a spark in the engine's cylinders, triggering combustion and starting the engine. The ignition coil also plays a synchronizing role, deciding when each spark plug will fire.

Older engines have only one coil, equipped with an ignition head that distributes power to all the spark plugs. Modern engines have multiple coils, but no distributor. The coil can handle one or two spark plugs and can be mounted directly on the spark plugs.

The life of an ignition coil varies between 30,000 and 60,000 km. However, if the engine has a starting problem, the coil will need to be replaced. If one coil fails, replacing all the other coils is a good idea to avoid an imbalance in the ignition system.

A multimeter is a small instrument used to check the resistance of the ignition coil. If the coil is in good condition, the readings should be between 0.7 and 1.7 ohms for the primary coil and between 7,500 and 10,500 ohms for the secondary coil.

Removing the coil

• Step 1: Disconnect the battery to avoid the risk of electric shock.
• Step 2: Remove the air filter housing
• Step 3: Disconnect spark plug leads
• Step 4: Disconnect high voltage coil harness
• Step 5: Disconnect ignition coil connector
• Step 6: Remove ignition coil fasteners
• Step 7: Remove ignition coil

Installing the Replacement Coil

Once the defective coil has been removed, replace it with the new coil and reassemble the entire system:

• Step 1: Make sure the new coil is identical to the old one.
• Step 2: Replace spark plugs
• Step 3: Check the ignition harness, and replace if necessary
• Step 4: Replace the ignition coil
• Step 5: Tighten the coil mounting screws
• Step 6: Reconnect the ignition coil high-voltage harness connector
• Step 7: Reconnect Spark Plug Wires
• Step 8: Replace Air Filter Housing
• Step 9: Reconnect Battery
• Step 10: Check engine operation

It's important to check and replace the spark plugs. As we've seen, these parts ensure an optimal combustion cycle. The same goes for the ignition coil set.

There are 5 types of ignition coils:

• The classic coil: Found on older ignition systems. It is unique in that it is the only coil that supplies high-voltage current to all of the spark plugs;
• The pencil coil: connected directly to the spark plug, it requires one coil per plug;
• Twin distributor (or high voltage) ignition coils: these consist of two coils. Each coil feeds two spark plugs simultaneously, without the need for an ignition head. It transmits power through wires;
• High-voltage distributor ramp ignition coil: The same principle as the twin distributor coil, it consists of two coils that feed two spark plugs at the same time, without the need for an ignition head. However, the ramp coil is placed directly on the spark plugs and is not connected by wires. It can be replaced in a single block;
• Dual independent coils: again, the same principle as the previous two, with two coils each feeding two spark plugs in parallel, without ignition heads, and mounted directly on the plugs. Each coil can be replaced independently.