Have you noticed that lately, your car seems to run more sluggishly than usual? Have you been making more frequent trips to the gas station, or have you started hearing strange coughing or popping noises? If any of this sounds familiar, fouled or dirty spark plugs could be the culprit.

Over time, fouled spark plugs can start to cause damage to your engine. Read on to learn more about fouled spark plugs, what to look for, and how to deal with this problem in your car.

What Are Spark Plugs?

Before we dive into the issues of fouled spark plugs, let’s talk about what spark plugs are in the first place. Gasoline car engines run off of a process called internal combustion, a series of small, controlled explosions that give your car the energy it needs to move forward. Your engine creates dozens of these explosions every second to keep your car running.

Your spark plugs are what your engine uses to create these explosions, which happen inside your car’s cylinders. They create an arc of electrical energy that ignites the gasoline inside your car’s cylinders. The gasoline then explodes, and your car keeps rolling down the road.

How Do They Work?

The internal combustion process revolves primarily around your car’s cylinders, pistons, and spark plugs. You have a fuel injector that sprays a small amount of aerosolized gasoline into your cylinder while the piston is at the bottom of the chamber. The piston then moves up, compressing that gasoline and air mixture and creating higher levels of pressure.

When your piston reaches the top of its cycle, your spark plug creates that arc of electrical energy we discussed. The compressed gasoline ignites and explodes, expanding rapidly and pushing the piston back down to start the cycle repeatedly. This pistons’ movement is what drives your engine, giving it the momentum it needs to turn your wheels and propel your car down the road.

What Is Spark Plug Fouling?

Although spark plugs are designed to last through millions of these controlled explosions, as you might imagine, they can start to show some wear over time. One of the most common forms of wear on spark plugs is spark plug fouling. Spark plugs are self-cleaning to a degree, but they can get dirty over time, especially if you don’t do much highway driving.

As your spark plugs get used, small amounts of fuel residue or ash may start to build upon them. If it’s not burned off by highway or full-throttle driving, it can start to interfere with the electrodes that generate that electrical arc. Your spark plugs may not be able to work as efficiently, and, over time, they may stop working altogether.

Reduced Gas Mileage

One of the first symptoms of fouled spark plugs that you may notice is the reduced gas mileage. You might find that your fuel simply isn’t going as far as it used to or that your mileage per gallon rating has dropped. While this can have to do with other routine wear and tear on your car, it may also result from fouled spark plugs.

When your spark plugs are fouled, they can’t create as effective a spark and may not fully ignite the gas in your cylinder. This means your car can’t get the full power of that bit of gasoline and will need to use more to go the same distance. Fouled spark plugs will cause a sudden drop in your fuel economy, so be sure to keep an eye on how often you’re going to the gas station.

Slower Acceleration

You may also notice that as your spark plugs get fouled, your car doesn’t accelerate as well as it used to. You may have to step a little harder on the gas to get going after a red light, and it may take you longer to get up to speed on the highway. Your car may also start to feel sluggish overall, as though you’re driving through thick mud everywhere you go.

This sort of dragging also traces back to your car’s inability to use its fuel as efficiently as it can with clean spark plugs. When your spark plugs aren’t firing as well, they can’t provide the sort of power your car needs to run. It will take longer for your car to get enough power to really get going after a stop.

Hard Starts

You might not be too surprised to learn that bad or fouled spark plugs could cause your vehicle to have hard starts. After all, your spark plugs are what launches the initial internal combustion process. With no working spark plugs, your vehicle can’t get the ignition; it needs to start running.

You might notice that you have to crank your car for a little longer before the engine actually catches and starts to turn over. This may get worse over time until your vehicle refuses to start at all. If the battery and gas tank seems okay, you may want to turn your attention to the spark plugs.

Engine Misfires

When your car is running, you should hear the engine’s smooth purring and the shift if it transitions through gears. But you might start to notice that your engine is hesitating or misfiring. You might notice a popping or sneezing sound as you roll down the road instead of a continuous hum.

This sort of misfire noise could be an indication that your spark plugs are bad or fouled. If the spark plug can’t make a solid electrical arc, it may fail to ignite the gas entirely. This can cause that popping sound you hear, and you may need to take your car to a mechanic immediately to avoid damage to your engine.

Rough Idling

Your car may do fine when it’s rolling down the road and running at its normal operating temperature, but you might notice that it’s not idling as smoothly as normal. You might be able to feel your vehicle vibrating when you’re sitting at stoplights or before you turn your car off in a parking lot. You might also hear it “coughing” or making other such noises while you idle.

Rough idling can be the result of fouled spark plugs for much the same reason as engine misfires. However, you may notice rough idling and no misfires because of the self-cleaning nature of spark plugs. When your engine is running at a higher temperature as it’s running down the road, it can burn off some of that residue, which can allow your spark plugs to function better.

Carbon Fouling

There are a few different things that can cause your spark plugs to become fouled. One of the most common is called carbon fouling and is the result of a fuel mixture with too much fuel and too little air. While this might seem like a good thing for getting the most power out of your car, it can start to foul up your spark plugs over time.

When your car is running a healthy fuel mixture, the gasoline will oxidize and turn into carbon monoxide and carbon dioxide gases. But when you have too much fuel in the mixture, some of the gasoline carbon can turn into deposits that stick to your spark plugs. If this is the case in your car, the problem is likely the result of a problem with your engine’s air intake system or fuel injectors.

Oil Fouling

Dirty spark plugs may also be the result of oil fouling rather than carbon from gasoline. This happens when too much engine oil makes its way into your cylinder. When combustion goes off, that engine oil can coat your spark plug in a shiny, black layer that smells like engine oil.

There can be several different reasons your car may have too much oil in the combustion chamber. In most modern cars, the problem usually originates in the positive crankcase ventilation system. You may have leaks around your piston rings, valve stem seals, or other parts of the PCV system.

Coolant Leaks

Coolant leaks can also sometimes cause a spark plug to become dirty and start malfunctioning. Most modern coolants are designed to have reduced phosphate, zinc, and other such minerals to prevent this from happening. But if a coolant leak goes unresolved for long enough, it can start to clog up your spark plugs.

Most of the time, your coolant leak will be coming from around an intake manifold or a head gasket. If coolant gets into the cylinders, it can burn and create an ashy, white deposit on your spark plug. You may also notice other symptoms related to a coolant leak before your spark plugs begin to misfire.

Check Your Spark Plugs

If you notice any of the symptoms we’ve discussed here, you may want to check your spark plugs to see if they’re fouled or not. If you don’t have a lot of experience working on cars, you might also want to consider taking your car to a mechanic. While spark plugs aren’t necessarily difficult to deal with, they are an integral part of your car’s operation and should be cared for properly.

The first thing you need to do to check your spark plugs is to disconnect the spark plug lead and clean the surrounding area to keep debris from falling into the combustion chamber. Use a spark plug socket to remove the plug and look for any deposits on the end of the plug. If there are only light deposits, you can clean them off, but stubborn deposits will call for a replacement.

How to Clean Spark Plugs

If your spark plugs only have a light coating of deposit on them, you may be able to clean them off and keep using them. You can buy a spray-on plug cleaner designed to work specifically on spark plugs. Use this and a wire brush or a sturdy knife to remove any deposits on the end of your spark plug.

However, it would help if you also kept in mind that those deposits got started for a reason. Whatever issue caused your spark plugs to get fouled will not be resolved by simply cleaning them. You may still need to take your car to a mechanic to address the underlying issue that’s causing your spark plugs problems in the first place.

How to Change Spark Plugs

If your spark plugs have thick, stubborn deposits on them or the porcelain is cracked, you may need to replace them. It would be best if you also replace any spark plugs whose electrodes have been burned away.

To replace spark plugs, remove them the same way you would to check them. Get new spark plugs appropriate for your vehicle and insert them in place of the old spark plugs. Make sure they attach in properly and that you reattach the spark plug lead before you try to start your car.

Learn More About Spark Plugs

Spark plugs are a critical part of how your car runs, but they can become dirty or fouled over time. If you notice your car lagging, making strange noises, or using more gas than usual, it’s a good idea to get your car to a mechanic or check your spark plugs yourself. You also need to make sure to resolve the original issue that caused your spark plugs to get fouled so it doesn’t happen again.

If you’d like to find your next dream car, check out the rest of our site at Viking Motors. We offer new and used vehicles, as well as service and parts for your car. Check out our special deals today and start making your daily driver work better for you.