The Causes Of Carbon Fouling Spark Plugs

As an important component in gasoline engines, spark plugs can also be used as an indicator of how the engine's performance happened before. The term can be used to diagnose the condition of the engine.

The trick is to pay attention to the color around the spark plug head (the end with the electrode). Through the color display on the spark plug head, we can know the engine's condition in the car. Is this engine working normally, experiencing overheating (too hot), or even wasteful fuel.

As we know, the spark plug head is located in the combustion chamber and the valve. The color that appears on the spark plug head is a reflection of the combustion effect that occurs in the combustion chamber.

Engines with normal combustion conditions are characterized by an even grayish-brown color around the spark plug head. In addition, the condition of the spark plug head will also look clean, and there will be no visible build-up of scale or deposits of combustion residues.

Meanwhile, for overheating conditions, the entire surface of the spark plug head is marked with a dominant yellow and white color; even in some conditions, the tip of the electrode is eroded so that the spark plug gap becomes larger.

How about carbon fouling spark plugs? The black color of the carbon fouling spark plug indicates the combustion conditions in the engine are very problematic. Generally occurs due to the fuel mixture that is too rich (a lot) and the occurrence of oil leakage so that the oil enters and burns in the combustion chamber.

The amount of fuel that is too much will make the combustion incomplete, leaving dark black soot in the combustion chamber. Even so, the oil that enters the combustion chamber will be difficult to burn and will even stick to the entire wall of the combustion chamber.

So, what are the causes of carbon fouling spark plugs? See information on the causes of carbon fouling spark plugs below.

1. Dirty and clogged air filter

The first cause of carbon fouling spark plugs is the result of a dirty and clogged air filter. The air filter is important in filtering dirt and dust before entering the combustion chamber.

If dust and dirt are allowed to accumulate for a long time, both of them will form lumps that settle on the filter surface. Even some dust and dirt are sucked into the intake, so it often becomes a barrier for air to enter the intake. In the end, the air filter will be completely clogged so that only a small amount of clean air can enter the combustion chamber.

A clogged air filter will directly affect the engine performance. Usually, the engine becomes powerless, and the fuel becomes more wasteful. In addition, the amount of fuel that is too much also often causes incomplete combustion. In effect, the combustion results often leave enough black soot to make the car's spark plugs turn black dry.

2. Abnormal injector spray

The next cause of dry carbon fouling spark plugs is abnormal injector spray. Usually, this happens when the injector spray is not in the form of a mist but rather like a rush.

This rush-like injector spray (not in the form of a mist) makes the fuel more difficult to burn than fuel already in the mist form. As a result, soot will appear and stick to the head of the spark plug. It is what can eventually cause the carbon fouling spark plugs.

Generally, this abnormal spray injector often occurs due to dirty fuel. It could be cause the fuel filter has never been cleaned or replaced, the fuel tank has never been drained, or it uses contaminated fuel.

3. Weak ignition coil

A weak ignition coil (example: increased coil resistance) will affect the number of sparks at the spark plug. Keep in mind that the piston compresses the air and fuel mixture. The compression pressure will affect the results of the sparks that appear on the spark plug head.

When the ignition coil is weak, the spark on the spark plug will also change and shrink. In effect, the ability of spark plugs to ignite the fuel mixture at the right time is reduced. It will result in incomplete combustion so that soot will appear, which is the cause of carbon fouling spark plugs.

4. Ignition timing too slow

Ignition timing is the time when the spark plug sparks just before piston compression reach TDC (Top Dead Center). For some injection cars produced before 2012, the ignition timing still needs to be adjusted periodically. Usually done using a tool called Timing light.

Along with the use of the vehicle, the ignition timing often shifts (due to a loose adjustment nut or the spark plug head being too worn) so that it can affect the combustion process that occurs in the combustion chamber.

Ignition timing that is too slow causes the combustion process to be incomplete and often produces soot in the remaining combustion products. This soot is what often makes car spark plugs go-to black.

5. Using the wrong type of spark plugs

The next thing that can cause carbon fouling spark plugs is using the wrong type of spark plug. Car spark plugs are divided into two types, hot spark plugs and cold spark plugs.

The use of inappropriate spark plugs will cause the ceramic cleaning process on the spark plug (which usually occurs by itself due to the temperature in the combustion chamber) to be not optimal.

As a result, the crust that the hot temperature in the engine should waste continues to stick to the spark plug head. It causes the spark to be disturbed, and making the combustion is not complete. As a result, black soot appears on the spark plug head.

Also read:

• When To Change Spark Plugs In A Car? Here's The Explanation
• The Causes Of Car Spark Plugs Wet With Oil
• How To Check Ignition Coils The Easy Way

6. Oil leak in valve steam seal

The next cause of carbon fouling spark plugs is the result of an oil leak in the valve seal. Oil leaks in the valve seal will make the engine oil enter the combustion chamber through the valve stem seal and fall into the chamber.

The oil entry into the chamber will certainly result in incomplete combustion, and also, the chemicals in the engine oil will mix with the air-fuel mixture. As a result, incomplete combustion and car spark plugs become black and wet with engine oil. Not infrequently, the exhaust smoke produced will be very thick.

7. Pistons oil rings are worn-out

The worn-out oil ring on the piston is the last thing we know can cause carbon fouling to spark plugs. There are three rings on a car piston so that compression can be maximized, namely the compression ring, rinse ring and oil ring.

When the oil ring is worn-out, the engine oil attached to the cylinder wall will also enter the combustion chamber and catch fire even though it is not completely burned. As a result, the car's spark plug is black, and there is oil around it.