A V6 engine can have as many as 1, 3, 6 or 12 ignition coils. The number of ignition coils depends on the make, model, and year of the vehicle along with the design of the ignition system.
The design of the ignition system could be distributor, coil on plug, or waste spark ignition. Modern engines typically have one ignition coil per cylinder.
So, a modern V6 engine will typically have 6 ignition coils. Some V6 engines have two cylinders that share one ignition coil. In this case, the V6 will only have 3 ignition coils. This is also the case for engines that use Twin Spark technology. Let’s take a deeper look at ignition coils.
Also known as a spark coil, an ignition coil is part of an engine’s ignition system developed to power the starter motor and ignition at the same time. It’s responsible for amplifying a car battery’s low voltage to thousands of volts. High voltage is necessary for providing enough of an electrical spark for a spark plug to ignite the air and fuel mixture in a piston for combustion.
Like computer CPU cores before the early 2000s, prior to the 1990s most engines had a single ignition coil. But those ignition coils on larger engines were bigger to give a better spark. When it comes to spark and ignition, the entire design consists of an ignition coil, a coil pack or coil for each cylinder. Again, most modern engines have one ignition coil for every spark plug.
The Original Ignition Coil
Ignition coils have been around for more than 100 years. Old ignition coils had copper wires wrapped around a piece of iron with two sets of windings (loop of copper wire). The first loop of copper wire is called the primary which contains hundreds of turns of winding. The second loop is called the secondary which contains thousands of copper wires.
Modern ignition coils have gone through several upgrades. Now most new engines have multiple ignition coils – one for each spark plug. And since they only need to power one or two spark plugs, the ignition coils in modern engines are much smaller than they used to be.
Twin Spark Engines
Some modern engines use Twin Spark technology. Here one piston is equipped with two ignition coils. As you can imagine, this helps increase combustion which results in increased performance. That means a twin spark V6 engine will have 12 ignition coils. European cars like Maseratis and Alfa Romeos are examples of cars with twin spark V6 engines.
How an Ignition System Works
Every automobile with an internal combustion engine has an ignition system. Although these ignition systems have undergone technological advancements throughout history, the basic function remains the same. An ignition system takes the low voltage of a car’s battery > amplifies that to a much higher voltage > and sends it to the spark plug to ignite the fuel-air mixture in the engine’s combustion chamber. Diesel engines don’t have an ignition system because they rely on compression to ignite the air and fuel mixture.
Types of Ignition Systems
There are basically three types of ignition systems:
Distributor ignition systems transfer high voltage current produced by the secondary coil to the right spark plug according to a firing order for the right amount of time set by either a mechanical or electronic ignition.
Coil-on-plug or COP ignition system places an individual coil on top of a spark plug. This design makes it easier for a spark plug to receive voltage by eliminating the need for a spark plug wire or distributor, which is why you’ll find it in many modern automobiles.
Waste spark are distributor-less ignition systems. DIS for short were introduced in the 1980s replacing the traditional distributor, coil, cap and rotor with coil packs which proved to be more reliable and required less maintenance.
Signs of Faulty Ignition Coils
A failing ignition coil or coil pack can usually set off a check engine light. The symptoms for either are the same:
Stalling happens due to loss of power often accompanied by a sluggish feeling when your vehicle is in motion caused by irregular sparks that can’t create the required combustion.
Misfiring results in sputtering or a jerky feel as you drive at normal speeds.
Backfiring is caused by unburned fuel suddenly escaping the exhaust system which is not normal on a modern engine.
Poor MPGs can be caused by many things but worsening gas mileage is a sign that an engine coil is going bad.
Rough Idling can be caused by a cylinder that isn’t getting enough of a spark for combustion.
As with many things automotive, if you don’t address these issues quickly, they will lead to significant engine damage.
How to Test an Ignition Coil
Warning: Take precautions. Testing an ignition coil can be dangerous when done incorrectly. If you don’t know how to do it properly, please seek an automotive professional. You can run an OBD-II check by using an OBD-II scanner: codes P0350 to P0362 relate to ignition coil issues.
You can also check the coils physically. Look for any obvious signs of damage around the ignition coil wiring. Also check the coil harness and connector for faults like bent terminal pins and loose connections. Water and electricity don’t mix. So, look for signs of moisture.
How Many Ignition Coils Should You Replace at Once?
Ignition coils are durable components in an engine. If they do go bad it’s usually because of bad spark plugs and/or spark plug wires. They can also fail if your air-to-fuel mixture is too rich or lean. Vibrations and engine heat can also lower their lifespan. But it’s unlikely that they would all go bad at the same time. So, there’s no need to replace them simultaneously. Just replace the one(s) you’ve identified as faulty.