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What Does It Mean If My Spark Plugs Are Black And Wet?
If you notice that your car’s engine is not running that well and inspect your spark plugs to find that they are black and wet you may be in for some trouble. Typically when your spark plugs are black and wet your engine is running rich which means that it is pumping in more fuel into the combustion chamber than is being burnt off during the combustion process.
What To Check If Spark Plugs Are Black and Wet
There are a few things that you can check if you pull out your spark plugs and notice that they are black and wet ranging from a check engine light all the way to your fuel filter. If you want to get to the
1. Check Engine Light
If you notice that your spark plugs are black and wet you first would want to see if your car has any check engine lights that may point you to the problem that could be causing this issue.
If your car does have a check engine light you can plug in an OBD2 scanner or scan tool to scan your vehicle and the associated codes that it is giving you. Once you have an idea of the different codes that your engine is giving you can then look them up to see what part may need replacing.
The OBD2 sensor will typically give you a generic code that will give you some sort of indication of where to look. I used to have an old Honda Civic that had a check engine light and when I looked up the code it basically said EGR malfunction.
Now as you may or may not know there are multiple parts to your EGR system of your car, not just one piece. That’s why OBD2 codes can be helpful but usually are not that descriptive.
2. Spark Plugs
If your spark plugs are old and have carbon buildup on them they may not be able to fully burn the air and fuel mixture in the combustion chamber, this can lead your spark plugs to end up black and wet over time. If you are unsure of the last time your spark plugs were replaced it would be a good idea to go ahead and replace them at this time, especially if they are currently black and wet.
New spark plugs should be able to fully burn all of the air and fuel mixture in the engine cylinder and little to no carbon buildup should continue to occur. If you replace your spark plugs and they are black and wet again in little to no time it may not be your spark plugs that are the actual issue.
To replace your spark plugs you would first want to buy or order new ones for your car and have them ready to go. Not all spark plugs are made the same so you would want to make sure that you get ones that are compatible with your vehicle. If you wanted to go through your local auto parts store to buy your spark plugs you can go to their website and put in your specific vehicle and they will list the different spark plugs that you can choose from that are compatible with your specific vehicle.
From there you can select the best ones that are going to work for your vehicle. To check out the current prices of spark plugs on Amazon click here.
If you want to read more about the differences between iridium and platinum spark plugs I’ve written an in-depth article that talks about the differences between both types of spark plugs and which are the best performing versus the cheapest. Iridium vs Platinum Spark Plugs Article.
3. Fuel Injectors
If your fuel injectors are cracked or damaged they can cause more fuel to be injected into your engine cylinders that may not fully be burnt off during the combustion process that will cause your spark plugs to turn black and wet over time.
If your fuel injector is cracked it can cause fuel from your fuel rails to be sent at a more rapid pace into the combustion chamber than is intended by the ECU of your engine. When your cylinder would try to burn the excess fuel in the engine cylinders not all of that fuel would be burnt during the process and some would be left on the spark plugs, the rest would be sent out the exhaust port.
Either way, having a leaky fuel injector is no good for your engine overall. If you need to replace your fuel injectors with new ones it isn’t that difficult of a job for someone that is somewhat handy on working on their own vehicles. You basically just loosen the bolts on your fuel rail, remove the fuel rail, and then remove your fuel injectors. The number of fuel injectors that your car has will depend on the number of cylinders that your engine has.
It’s a good idea that if you are going to be replacing your fuel injectors that you replace them all at the same time. Otherwise, you could have some fuel injectors that are working great and some that aren’t working well which can cause your engine to run unevenly and vibrate.
4. Air Filter
Another thing that you can check if your spark plugs are black and wet is your engine air filter. If you have not replaced your engine air filter in a long time it can get plugged up with dirt and debris over time. If your engine is not able to suck in the air easily this can cause the engine to compensate with adding in more fuel to try to complete the combustion process.
You should check your air filter to see if it is dirty you would want to go ahead and replace it. If you are unsure of how to check your engine air filter on your car it should be located at the end of your air intake that would flow into the top of your engine. If you are still unsure of where the engine air filter is located on your vehicle I would do a quick google search for a youtube video so that it could show you where it is located and how to replace your engine air filter.
5. Mass Airflow Sensor
Your mass airflow sensor or O2 sensor is designed to be able to measure how much air is coming in through your engine air filter and being delivered to the engine. If your mass airflow sensor is not able to accurately measure how much air is flowing through the air intake it will adjust the engine mapping for the worst possible conditions. This can ultimately cause your spark plugs to end up black and wet as your engine may be pumping more fuel into the cylinder to compensate for the lack of air coming in.
If your mass airflow sensor is going out it should be giving you a check engine light on your dashboard. If your check engine light points to an issue with your mass airflow sensor you would first want to try to clean your mass airflow sensor with mass airflow sensor cleaner that you can pick up at your local auto parts store. You do not want to touch the mass air flow sensor with your finger or a rag as this can cause it to malfunction.
If you clean your mass airflow sensor with mass airflow sensor cleaner and that does not get rid of your check engine light you would want to look at possibly replacing your mass airflow sensor with a new one. You can purchase a new mass airflow sensor online or through your local auto dealer.
6. Throttle Body
If your throttle body is dirty your engine will try to pump more fuel into your engine cylinders and cause your spark plugs to turn black and wet over time. Your throttle body sits on top of your engine and has flaps within it that open fully under full throttle and start to close up when you are just cruising. Over time your throttle body can start to stick from the debris that makes it past your engine air filter.
The good news is that you can typically clean your throttle body on your car with throttle body cleaner and a rag and this can alleviate your issues. It’s important that if you are going to be cleaning your throttle body with a rag that you use a clean rag so that you don’t risk dropping something on the rag into your throttle body. Your throttle body feeds directly into your engine’s cylinders so anything that you drop in there would go directly into one of the cylinders which could cause harm depending on what sort of debris it was.
Once you have your throttle body cleaner and clean rag you would want to remove your air intake that leads to your throttle body so that you can clean the throttle body. Once you have access to the throttle body you can now spray your throttle body cleaner into the throttle body and use your clean rag to remove any build-up of dirt around the edge of the throttle body and around the throttle body plates.
Spark Plugs Are Black And Wet – Conclusion
If you one day inspect your spark plugs and find that your spark plugs are black and wet the good news is that it can be fixed, the bad news is that there can be multiple different causes. There are many types of issues that can cause your spark plugs to turn black and wet over time.
I’ve listed the most common problems that can cause your spark plugs to turn black and wet but just know that the most typical cause of this is that your engine is pumping too much fuel into your engine cylinders. Once you find out why your engine is using too much fuel in the engine cylinders this should fix your issue.