Should I Replace Ignition Coils With Spark Plugs?

Ignition coils and spark plugs are two important parts of a vehicle. They work together to create the spark that ignites the fuel-air mixture in the engine. Should I replace ignition coils with spark plugs? The short answer is no. Change ignition coils with spark plug only if they’re worn out.

What is an Ignition Coil? 

Ignition Coil

In internal combustion engines, ignition coils are a critical component of the ignition system. They are the engine electrical components that boost voltage from the vehicle’s charging system (battery and alternator) and provide power to the spark plugs. Each spark plug contains its own ignition coil.

An ignition coil is composed of two wire coils wrapped around a central iron core. The primary coil, which is connected to the battery, is formed of thick wire with a few twists. The secondary coil is attached to the spark plugs and is comprised of thin wire with a high number of turns.

Ignition coils are required because the battery in a car produces a low-voltage current that is insufficient to ignite the fuel and start the engine on its own.

Difference between an Ignition Coil and Spark Plug?

Ignition coils and spark plugs are two of the most important parts of your car’s ignition system that need regular maintenance. 

In order to produce a spark, an ignition coil must turn the relatively low voltage supplied by a car battery into the much higher voltage required by the spark plug. There is a primary winding that is linked to the power source (the battery) and a secondary winding that is linked to the ignition system (the spark plugs). When you turn the key, you’re actually activating the primary ignition, which completes the circuit between the battery and the ignition coil. The coil’s magnetic field is therefore generated. This triggers the secondary ignition. It does this by momentarily severing the magnetic field surrounding the ignition coil, which in turn induces a current between the two coils. In this way, the battery’s 12 volts are amplified to almost 50,000.

However, your engine’s fuel-air combination is ignited by the spark produced by the spark plugs. A ceramic insulator serves as a buffer between the center electrode and the ground electrode. To ignite the fuel in your engine, an electrical current jumps across the spark plug’s electrode gap, thanks to the 50,000 volts or more supplied by the ignition coil.

Reasons to replace ignition coils

Ignition coils may need to be replaced for a variety of reasons, including:

  • Engine misfires are one of the most prevalent symptoms of a faulty ignition coil. When the coil does not produce enough energy, the spark plugs may not ignite properly, resulting in misfires, rough starting, and reduced power from the engine.
  • If the starting coil fails, the check engine light will illuminate. This can happen if the coil isn’t producing enough power or is producing too much.
  • Due to diminished engine performance, faulty ignition coils might result in poor fuel economy. If the engine isn’t running properly, it may not use as much fuel as it should.
  • It can be difficult to start the engine if the ignition coil does not transmit enough power to the spark plugs, especially when it is cold outdoors.
  • A faulty ignition coil can cause the engine to stall or abruptly shut down, which can be dangerous if it occurs while driving.
  • Ignition coils can be damaged by wear and tear or heat, causing the coil to fail and require replacement.

Considerations for replacing coil packs

If you want to know when to change your coil packs, the answer is easy: whenever any of these signs show up. Almost all of the signs are the same as when a spark plug is broken:

  • Bad performance from the engine
  • Disturbing engine noise
  • Crankshaft drag slowed down the car’s speed.
  • Every once in a while, smoke comes out of the exhaust.
  • Rough running engine
  • The “check engine” light doesn’t come on very often.
  • The petrol light has come on, but we don’t need to fill it up yet.

Should I replace Ignition Coils with Spark Plugs? 

Spark plugs and ignition coils have a very intimate working relationship with one another. Ignition coils and spark plugs both contribute to the generation of the spark required to ignite the fuel-air mixture; however, the sparks they generate serve unique functions, and one cannot be substituted for the other. 

Ignition coils are designed to last a long time, but they may eventually stop working properly due to age, heat, or other factors. If your ignition coils are failing, you may have misfires, rough idling, and diminished performance.

When it comes time to replace your vehicle’s ignition coils, it is critical to choose coils that are compatible with the make and model of your vehicle. If you select the incorrect coils for your vehicle’s engine, it could create extra problems and even engine damage. To ensure constant performance, it is critical to replace all of the coils at the same time, even if just one is faulty.

On the other hand, because spark plugs wear out faster than ignition coils over time, they usually need to be replaced more regularly. Spark plugs should be replaced every 30,000 to 100,000 miles, depending on the make and model of your vehicle, according to the manufacturer’s recommendations. Failure to change spark plugs as suggested may result in a decrease in performance, misfires, and an increase in emissions.

It is in your best interest to repair both of these components at the same time if the failure of your ignition coils was caused by worn-out spark plugs.

Why should I Replace the Ignition Coils with the Spark Plugs?

It is not recommended to replace ignition coils with spark plugs because they are two distinct components with distinct purposes. However, you may need to replace ignition coils or spark plugs in some cases. Here are some reasons why you might need to replace ignition coils with spark plugs:

They are simple to replace and install

You may need to remove components such as an intake plenum, but this will depend on the sort of engine you have and the number of ignition coils it has. After you have done all of the steps required to gain access to and remove the ignition coils, you will save time by changing the spark plugs while they are in an easily accessible position.

Improved Engine Performance

Simply replacing the spark plugs will increase the performance of your engine. Using outdated and worn-out spark plugs may result in a lack of acceleration and a drop in fuel mileage. Less spark prevents the fuel from being properly ignited, resulting in wasted gas. Catalytic converters can also be destroyed when gasoline is wasted and discharged into the exhaust.

Failure of the Ignition Coil

If one or more ignition coils fail, you may experience misfires, lower performance, and other issues. If this is the case, you will most likely need to replace the faulty coils in order to restore your vehicle’s performance.

Failure of the Spark Plugs

If your spark plugs are broken or worn out, you may have misfires, lower performance, and increased emissions. If this is the case, your vehicle’s performance may not be restored until the spark plugs are replaced.

Preventative Maintenance

Preventative maintenance includes changing the ignition coils or spark plugs in your automobile if it has a high mileage or if it has been a long time since the ignition system was serviced. This is especially critical if your ignition system hasn’t been serviced in a while. Misfires and lower performance may be easier to avoid in the future if this is done.

Related: Ignition Coil Maintenance: Guide to Proper Cleaning and Maintenance

Potential Issues with using Spark Plugs instead of Ignition Coils

Since spark plugs and ignition coils serve distinct purposes in a vehicle’s ignition system, swapping the two is not a practical option.  

But if you do, you can run into these issues:

One, there is insufficient voltage because spark plugs cannot generate as much power as ignition coils.

Second, the spark plug could be damaged if used in place of the ignition coil.

Third, the engine might be severely damaged, and spark plugs aren’t made to withstand the high voltage generated by ignition coils, so the situation could quickly deteriorate.

Fourth, the engine’s power, acceleration, and gas mileage could all suffer if spark plugs were used instead of ignition coils.

Fifth, because the engine could potentially backfire, it is not a safe practice.

The cost associated with upgrading to new coils or spark plugs

A coil-on-plug system may cost as little as a few hundred dollars, whereas a cassette-style system may cost more than a grand. Coil type and degree of difficulty in gaining access both affect pricing.

The final cost of a new set of spark plugs depends on how many cylinders your engine has and can range from $16 to $100.

Final Words

So, should I replace ignition coils with spark plugs? Not necessarily. As they both work with each other, sometimes one component might end up causing damage to the other. If this is the case, you have to replace both the ignition coil and the spark plug. 

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