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Can Spark Plugs Cause Misfire? (All You Need to Know)

Every engine comes equipped with spark plugs. The spark plugs are basically responsible for igniting the fuel mixture and creating a blow-up, which enables the engine to produce power.

That being said, you might be wondering if the spark plugs can cause a misfire. You might also want to know what problems a loose, or cracked spark plug can cause. Let’s find the answers to all your queries regarding spark plugs.

Can spark plugs cause misfire?

Spark plugs can cause engine misfire. In fact, one of the major reasons for misfiring during acceleration is shabby spark plugs. High erosion on spark plugs prevents them from igniting the fuel in the piston cylinder. Damaged spark plugs or faulty spark plug wires can also cause an engine misfire. 

When an engine misfires, it halts for a short period of time before returning to regular operation. And any defect on spark plugs can cause an engine misfire. This is due to the fact that spark plugs ignite the fuel in the piston which helps the engine to gain power and keep running.

If there is excessive corrosion on the spark plug, it won’t be able to burn the fuel located in the piston cylinder. In fact, a corroded spark plug can cause a misfire when the car is accelerating. A damaged distributor cap or broken plug wires can also cause the engine to misfire.

A random misfire can occur due to worn-out or damaged spark plugs. The engine can stop and start after a brief moment even when the car is running at full speed. Driving a car with a damaged spark plug and misfiring engine is not safe at all.

Can these spark plugs cause a misfire?

Let’s walk through this section to know whether the following spark plugs cause engine misfire or not –

Bad spark plug:

One of the main reasons for engine misfire is a bad spark plug. If the installed spark plug is bad, it won’t be able to ignite the fuels in the piston, resulting in an engine misfire.

Loose spark plug:

A loose spark plug can cause a misfire when the car is accelerating and running at full speed. This occurs because when the spark plug is loose it will sometimes fail to power up the engine by burning the piston cylinders’ fuel.

Oil in spark plug:

Oil in spark plugs usually doesn’t cause a misfire. However, if the oil in the spark plug reacts with the engine oil, it can cause an engine misfire.

Old spark plug:

Old spark plugs are usually eroded due to constant usage for a long period of time. As a result of the worn-out spark plugs, the pistons won’t function properly, causing an engine misfire.

Wrong spark plug:

The wrong spark plug will definitely cause an engine misfire. This is due to the fact that for igniting the fuel in the piston cylinder, a specific spark plug is engineered. If the specific spark plug for an engine is not installed, it will misfire while operating.

Cheap spark plug:

Cheap items are not always of poor quality. However, if the cheap spark plug is of unacceptable quality, it will fail to ignite the fuel, which will result in an engine misfire.

Stripped spark plug:

A stripped spark plug will work, but it might malfunction once in a while. When accelerating, the stripped spark plug can fail to ignite the fuel, misfiring the engine.

Wet spark plug:

Spark plugs that are covered with water or any other liquid will stop the engine from getting the desired spark to function properly. As a result, wet spark plugs can cause a misfire in the engine.

New spark plug:

New spark plugs rarely cause a misfire. In fact, to get rid of the engine misfiring problem, it is recommended to get new spark plugs.

Burnt spark plug:

Burnt spark plugs will fail to produce the required sparks for the engine. So, a burnt spark plug can cause the engine to misfire in any condition.

How to tell if a spark plug is misfiring?

You can tell if a spark plug is misfiring from various indications of your car. Lets’ have a look at how can understand if a spark plug is misfiring.

A weird sound will come from the engine:

When a spark plug misfires, it sounds like sneezing, popping, or banging. The weird sound usually comes from the engine when its rpm is between 1,500 and 2,500. This is a very effective and easy way to detect if your cars’ spark plug is misfiring.

Car won’t accelerate fast enough:

Your vehicle’s driving characteristics are presumably well-known to you. When you observe that your car or truck isn’t as responsive as it used to be, especially when accelerating, it could be due to worn spark plugs.

The vehicle won’t start normally:

A spark plug basically ignites a spark to start an engine. So, when a vehicle doesn’t start normally, it can be because of the spark plugs misfiring. A defective or corroded spark plug fails to produce the spark to power up the engine.

Increased fuel consumption:

The gas mileage of your vehicle will hamper when your spark plugs are on their last days. This is because old or damaged spark plugs don’t burn the fuel that goes into the engine efficiently. As a result, if a spark plug misfires, your vehicle’s fuel consumption will increase significantly.

How to tell which spark plug is misfiring?

Each cylinder of a vehicle is equipped with a spark plug. A car normally has four cylinders, as a result, a car usually has four spark plugs.

You can tell which spark plug is misfiring quite easily by knowing a few simple methods. Have a look at how you can tell which spark plug is misfiring:

Using an infrared thermometer:

To detect which cylinders’ spark plug is misfiring, point the infrared pointer at each exhaust port one after another. The cylinder whose temperature is not similar to the other three cylinders is basically misfiring.

A functioning cylinder will have a temperature near 200 degrees Fahrenheit. Whereas, a non-functioning cylinder will have 130 degrees Fahrenheit temperature.

Scanning device:

To tell which spark plug is misfiring, simply plug the device in the OBD port. The device will let you know which cylinder and the spark plug are misfiring. However, the scanning device only works on advanced and modern cars.

Will new spark plugs fix misfire?

A spark plug usually misfires when it becomes old and worn out. An engine also misfires if the spark plug is loose, spark plug wires are damaged, or the installed spark plug is of the wrong type. If any of these is the reason for the engine misfire, new spark plugs will fix the misfire.

Why is my car misfiring after changing spark plugs?

An engine doesn’t only misfire because of damaged or faulty spark plugs. It can also occur for various other reasons like fuel delivery issues, ignition system problems, control circuit problems, and more. 

So, if your car is not misfiring because of spark plugs, it will still misfire after changing the spark plugs.

In addition to that, each cylinder requires a specific type and model of spark plugs. So, if the new spark plugs are not of the right model, they will still misfire even after replacing the old ones.

What problems can a bad, loose, or cracked spark plug cause?

A bad, loose, or cracked spark plug can cause various problems as they are the fundamental parts of the fuel ignition of a cylinder in an engine. It will cause various severe issues in a car.

Let’s take a look at what problems a loose, bad, or cracked spark plug can cause.

Engine misfiring:

Engine misfiring is one of the most common and drastic problems a loose, or cracked spark plug can cause. A loose, bad, or cracked spark plug can cause an engine misfire, reducing its overall performance.

The vehicle will suddenly stop:

A bad, loose, or cracked spark plug can fail to ignite the fuel-air mixture in the cylinder. This will bring the engine to a standstill suddenly. It can happen even when the car is running at full speed, which can be intensely dangerous.

Uneven idling:

When a spark plug is bad, loose, or cracked, the car will become quite rough when driven at idle speeds. The car engine will also create vibrations as a result of a faulty spark plug.

Final Thoughts

Spark plugs can definitely cause misfires by not producing the perfect spark for the engine to run and function properly. It can happen due to loose, rusty, corroded, or stripped spark plugs. Any residue of water or other liquids in the spark plug can also cause an engine misfire.