Carbon build up is a very common occurrence in internal combustion engines. There is always some slight carbon buildup no matter if the engine is good or it’s plagued with problems.

Also depends much on the configuration, since some engines are more prone to create carbon buildup than others. Namely the direct injection engines or GDI as they are branded by Hyundai.

Carbon buildup occurs because the explosions in the engine are not perfectly timed or you are having bad spark plugs. In the combustion process, everything needs to follow the same timing in order to get the right power from the engine.

If it’s not, you will get misfires, loss of compression, low power, and other symptoms associated with this. And one of the biggest issues with this is the carbon buildup that occurs on the valves and the top of the pistons.

In this article, we are going to discuss carbon build up in engine. What are the main reasons why there is carbon buildup inside the engine and later we are going to cover the solutions for this problem. How you can clean the carbon deposits the right way. So, without further ado, let’s get into it.

Carbon In Engine Symptoms

So, you are probably asking yourself what are the carbon in engine symptoms or direct injection carbon buildup symptoms?

In this chapter, we are going to list all of the symptoms of carbon buildup in engine and what you can do in order to fix these issues, and also how to prevent them from happening in the first place.

Engine Misfires

Can carbon buildup cause a misfire? Yes, it can, engine misfires are probably the most frequent symptom of carbon buildup in engine. When your engine doesn’t run well and you have some problems with running the engine like stalling and noise coming from a specific cylinder. One of the possibilities is that the engine is misfiring.

An engine can misfire from many different things. Bad valve adjustment can be one of the causes of this issue. If your valves are not adjusted the engine will not work properly. Other reasons can be bad coils, and bad spark plugs. We are going to discuss them in the next chapters.

Bad Spark Plugs

Spark plugs are one of the most important aspects of the combustion process, without sparkplugs we wouldn’t have anything. They make the spark and they ignite the fuel that burns and the explosions move the pistons inside.

If a spark plug doesn’t work or does not produce a strong spark, the result will be unburnt fuel and misfires. Unburnt fuel or delayed explosions can create carbon buildup and your engine will not work properly. If you are running your engine like this for a long time it can cause a lot of carbon buildup on the head and the valves will not seat properly on the head.

In this case, you will start losing compression on your engine. Аnd your car will no longer be able to make the pulls and will work very badly. You will lose a lot of power and you will feel like you are driving on three cylinders.

The fix for this problem is fairly simple and you can do it at your home without any assistance because spark plugs are really simple to swap. You will just need a wrench to unbolt the spark plug. Bolt the new spark plug in and connect the coil or cable. Then you are good to go.

Bad Engine Coils

A bad engine coil can also cause misfires and carbon buildup inside the cylinder. The engine coils are carrying the spark to the spark plug. And in order to deliver the spark, they have to be in proper working order.

In order to diagnose a bad coil issue, you will need an OBD2 scanner tool. These tools can be found on Amazon, eBay. They are pretty much everywhere, just getting a good scanner tool. The more advanced tools have more options and you can diagnose the issues much better than with ordinary tools that cost a few dollars. With this tool, you basically have everything at your glance.

If the coil is not working properly, it has to be replaced. Unfortunately, coils are pretty expensive and can cost you more than $1000 to find a replacement coil for your vehicle. They are really simple to install and everyone can do this job DIY. You just unplug the old coil and plug the new coil in, easy peasy.

Engine Stalling

If you are having a carbon build up in engine that is excessive, your car may even possibly stall at some point. It will be difficult to maintain proper combustion and the engine will decide to shut off.

This can happen if you have a couple of cylinders that are affected by carbon buildup and the carbon buildup is so excessive that the engine cannot keep itself running and shuts down.

Bad Fuel Efficiency

Another symptom of carbon buildup is bad fuel efficiency. Especially if there are misfires in the cylinders caused by bad spark plugs or bad coils. The engine misfires and drops too much fuel inside the combustion process to keep running.

In this case, the computer is confused and is trying to keep the engine in working condition, that’s why it drops more fuel. For this symptom, a possible cause can also be bad sensors. Especially bad O2 sensors that are measuring the exhaust gasses that are coming out of the exhaust pipe.

This sensor is crucial when it comes to the proper combustion process. Another sensor that can play a role is the mass airflow sensor that is measuring the amount of air that is injected inside of the engine.

Bad Acceleration

When you have a carbon buildup and malfunctioned combustion process, bad acceleration is one of the symptoms that can be present. If your car doesn’t accelerate well it means that something is wrong. This can be caused by bad spark plugs, bad coils, O2 sensors.

In this case, the best solution is to place your car on a car scanner tool and see what errors are you getting from it. This is crucial if you want properly to diagnose and solve this problem.

Loss Of Power

Today’s cars are specially programmed to go into leap mode when there is something really wrong. In this case, you are going to lose all the power of the car and you will only have enough power to move your car to a safe place.

In order to bring your car to proper working order, you will have to take your car to a mechanic that will diagnose the issue and also find a fix for it. Then he can reset the computer and make your car drivable again.

What Causes Carbon Buildup On Pistons?

Carbon on pistons as we said is usually caused by bad combustion. You have a faulty spark plug or coil that is causing the car to misfire and these misfires can cause carbon buildup to appear inside the engine.

Another thing that can cause carbon buildup on pistons are leaky valves. Valve seals can fail and the oil can come down into the cylinders. This can often happen and can result in black smoke from the exhaust. If you have black smoke coming out of the exhaust it means that there is oil inside the combustion chamber.

You will have to replace the seals on your valves and also clean off the heads from all the carbon buildup that is on them in order to bring them back to perfect working order. This can be costly but it’s worth it. If you love your car nothing is difficult and everything can be sorted.

How Do You Tell If You Have Carbon Buildup In Engine?

The easiest way to tell if you are having carbon build up in engine is by removing the spark plugs. If they are all black that means that there is bad combustion in the specific cylinder. Every spark plug will tell a different story but we are going to leave that for another article.

How To Check For Carbon Build Up?

There are a couple of ways how you can check if you have carbon build up in engine. The simplest way is to check your spark plugs.

In order to perform this check, you need to remove all of the spark plugs, one by one, and observe the part that is creating the spark. See if they are black. If they are black that means that there is a lot of carbon deposits inside the engine. If they are black and oily it means that you are getting oil inside your combustion chamber and your valves don’t seal properly.

Another way to inspect this problem is with a camera. If you have one of these cameras that can fit into tight places this is a good idea to do. Just remove the spark plug and place the camera into the hole and observe the inside of the cylinder. If there is a lot of carbon deposits on the top of the piston it means that you have a problem. You need to further investigate this and find a proper solution.

There is also another way to see if there is carbon buildup and that is by removing the head. In order to remove the head, you need to remove many accessories in the car like the fuel lines, intake manifold, coils. Everything needs to come out and then you can open the head and inspect the valves. Then you can manually remove all of the deposits and clean your engine heads and pistons the right way.

How To Clean Carbon Build up In Engine

Cleaning carbon buildup can be a tricky job to do. Mostly because you don’t have any working space and you can’t reach the carbon that is on the top of the pistons and on the top of the valves.

There are many products that name themselves as carbon build up engine cleaners, but their effectiveness is doubtful.

The best way to clean carbon is the good old manual way. And to do this job you need to remove the head of the engine.

You will need a wheel brush in order to brush off the contaminants that are on the head valves and the combustion chamber. You can also clean off the ports and make them nice and shiny again.

In order to clean off the pistons, you will need to rotate the engine and turn the pistons until they reach the top. Clean them off and then repeat the process until you clean them all.

Then it’s reassembling time. You need to place everything in proper order. And if you are having an interference engine you need to make the timing right. You don’t want to bend your valves.

Engine Carbon Buildup Removal Cost

Carbon buildup cleaning cost depends on which way you want to go. If you want to completely clean the intake and the heads and pistons. It can cost you some money because the engine needs to be disassembled and the mechanic needs to have proper tools in order to clean the debris. At a mechanics shop, this job will cost more than $700. Depending on where you take your car to.

A wheel brush will do the trick. If you are having a beater car you can also experiment and do this job by yourself. You will need only a wheel brush and a power tool, also a new head gasket. And a lot of time. This will be a big learning curve so if you are feeling that you are prepared you to start wrenching.

How To Prevent Carbon Buildup

Carbon buildup can be prevented very simply. You just need to service your car at regular intervals and do some tune ups in the meantime.

By this we mean checking all the spark plugs and coils, scan the car for codes and solve the issues before they appear. If you solve all the issues before they appear you will not going to have any of these issues and you will enjoy your car more.

Also, if you do some of these things on your car by yourself you will be proud that you did it.

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About The Author

CarGuy

CarGuy also known under his real name Goran T. is an experienced writer who has written thousands of articles for many reputable car-related websites such as Drifted.com and MotorVerso.com. He also has a lot of experience wrenching on his cars at his home garage where he collects the knowledge he then shares with our readers here on C&W.

Carbon Build Up In Engine – What Are The Main Symptoms?