Why are black spark plugs

Appearance black soot on spark plugs can tell the car owner about the problems that are in his car. The reasons for this phenomenon may be poor-quality fuel, ignition problems, a mismatch in the air-fuel mixture, or an incorrectly tuned carburetor, and so on. All of these problems can be diagnosed fairly easily just by looking at black spark plugs.

Possible causes of soot

Before answering the question of why the candles are black, you need to decide how exactly did they turn black?. After all, it depends on which direction to search. namely, candles can blacken all together, or maybe only one or two of the set. also, a candle can turn black only on one side, or maybe along the entire diameter. also distinguish the so-called "wet" and "dry" soot.

It should be noted that the rate of appearance and the nature of soot directly depends on the existing malfunctions (if any):

• Nagar on new candles begins to form at least after 200-300 km of run. Moreover, it is desirable to drive along the highway with approximately the same speed and load on the internal combustion engine. So the candles will work in the optimal mode, and it will be possible to more objectively assess the condition of the car's units.
• The amount and type of soot depends on the quality of the fuel used. Therefore, try to refuel at proven gas stations, and not drive on gasoline or similar mixtures. Otherwise, it will be difficult to establish the real cause of the appearance of soot (if any).
• In the carburetor internal combustion engine, idle speed must be correctly set.

Now let's move on to the question of why black soot appears on the spark plugs. May be 11 basic reasons:

1. If you notice blackening on only one side, then most likely this is caused by valve burnout. That is, the soot on the candle falls from below to the side electrode (and not to the central one).
2. The cause of black candles may be valve burnout. The situation is similar to the previous one. Carbon deposits can penetrate the lower electrode.
3. an incorrectly selected glow number of a candle causes not only its damage in further operation, but also uneven blackening of the first. If the mentioned number is small, then the shape of the soot cone will change. If it is large, then only the top of the cone will turn black, and the body will be white.
   The glow number is a value that characterizes the time it takes for the candle to reach glow ignition. With a large glow number, it heats up less, respectively, the candle is cold, and with a smaller number, it is hot. Install spark plugs with the glow rating specified by the manufacturer in the internal combustion engine.
4. A uniform black coating on the candles indicates late ignition.
5. Black candles on the injector or carburetor may appear due to the fact that the air-fuel mixture produced by them is too enriched. As for the first, there is a high probability of incorrect operation of the mass air flow sensor (DMRV), which provides information to the computer about the composition of the mixture. it is also possible that the fuel injectors have leaked. Because of this, gasoline enters the cylinders even when the nozzle is closed. As for the carburetor, the reasons may be the following reasons - incorrectly adjusted fuel level in the carburetor, depressurization of the needle shut-off valve, the fuel pump creates excessive pressure (the drive pusher protrudes strongly), depressurization of the float or its grazing behind the walls of the chamber.

   "Dry" soot on a candle

6. Significant wear or depressurization of the ball valve of the power mode economizer on carburetor ICEs. That is, more fuel enters the internal combustion engine not only in power, but also in normal modes.
7. A clogged air filter may be the cause of a black spark plug. Be sure to check its condition and replace if necessary. also check the air damper actuator.
8. Problems with the ignition system - an incorrectly set ignition angle, a violation of the insulation of high-voltage wires, a violation of the integrity of the cover or distributor slider, breakdowns in the operation of the ignition coil, problems with the candles themselves. The above reasons can lead to interruptions in sparking, or a weak spark. Because of this, not all fuel burns out, and a black glow forms on the candles.
9. Problems with the valve mechanism of the internal combustion engine. namely, it can be a burnout of the valves, or their non-adjusted thermal gaps. The consequence of this is incomplete combustion of the air-fuel mixture and the formation of soot on candles.
10. In injection cars, it is possible that the fuel regulator is out of order, and there is excess pressure in the fuel rail.
11. Low compression in the cylinder corresponding to the black spark plug. How to check compression you can read in another article.

Usually, when the late ignition is set and running on an enriched fuel-air mixture, the following consequences appear:

• misfiring (error P0300 appears on injection ICEs);
• problems with starting the internal combustion engine;
• unstable operation of the internal combustion engine, especially at idle, and as a result, an increased level of vibration.

further we will tell you how to eliminate the listed breakdowns and how to clean the spark plugs.

What to do when soot appears

First of all, you need to remember that oil pollution and overheating, which results in soot on spark plugs, very harmful to the ignition system. Overheating is especially terrible, because of it there is a possibility of failure of the electrodes on the candles without the possibility of their recovery.

If only one blackened candle appeared on your car, then you can diagnose a breakdown by simply swapping the candles. If after that the new candle also turns black, and the old one clears up, it means that the matter is not in the candles, but in the cylinder. And if nothing has changed, then questions arise about the performance of the candle itself.

Oil deposits

In some cases, candles may be wet and black. The most common cause of this fact is the ingress of oil into the combustion chamber. Additional symptoms of this breakdown are as follows:

Oil on a candle

• difficult start of the internal combustion engine;
• omissions in the work of the corresponding cylinder;
• ICE twitches during operation;
• blue smoke from the exhaust.

Oil can enter the combustion chamber in two ways - from below or from above. In the first case, it enters through the piston rings. And this is a very bad sign, because it often threatens engine overhaul. In rare cases, you can do with the decoking of the motor. If oil enters the combustion chamber through the top, then it goes from the cylinder head along the valve guides. The reason for this is the wear of the valve stem seals. To eliminate this breakdown, you only need to select new, high-quality caps and replace them.

Carbon deposits on the insulator

Red soot on a candle

In some cases, carbon deposits that naturally form in the combustion chamber can break away from the piston at high engine speeds and stick to the spark plug insulator. The consequence of this will be gaps in the work of the corresponding cylinder. In this case, the internal combustion engine will “troit”. This is the most harmless situation, why spark plugs turn black. You can eliminate it simply by cleaning their surface or replacing them with new ones.

If your internal combustion engine has black and red candles, then this means that you are pouring fuel with an excess amount of additives with metals. It cannot be used for a long time, for the reason that over time, metal deposits form a conductive coating on the surface of the candle insulator. Sparking will deteriorate and the candle will soon fail.

Cleaning spark plugs

Cleaning spark plugs

Candles should be cleaned regularly, as well as inspecting their condition. It is recommended to do this after about 8 ... 10 thousand kilometers. It is very convenient to do this at the time of changing the oil in the internal combustion engine. However, with the onset of the symptoms described above, it can be done earlier.

It’s worth mentioning right away that the old method using sandpaper to clean the electrodes should be used not recommended. The fact is that this way there is a risk of damage to the protective layer on them. This is especially true for iridium candles. They have a thin center electrode coated with iridium, a semi-precious and rare metal.

To clean spark plugs you will need:

• detergent for removing plaque and rust;
• disposable plastic cups (after the end of the cleaning procedure, they must be disposed of, they cannot be used for food products in the future);
• a thin brush with a hard pile or a toothbrush;
• rags.

The cleaning procedure is performed according to the following algorithm:

Cleaning procedure

1. A cleaning agent is poured into a glass prepared in advance to a level in order to completely immerse the candle electrodes (without an insulator) into it.
2. Immerse candles in a glass and leave for 30 ... 40 minutes (in the process, a chemical cleaning reaction appears, which can be observed with the naked eye).
3. After the specified time has elapsed, the candles are taken out of the glass, and using a brush or toothbrush, plaque is removed from the surface of the candle, paying particular attention to the electrodes.
4. The candles are washed in warm running water, removing the chemical composition and dirt from their surface.
5. After rinsing, wipe the candles dry with a cloth prepared in advance.
6. The final stage is to dry the candles on the radiator, in the oven (at a low temperature of +60 ... + 70 ° C) or with a hair dryer or fan heater (the main thing is that the water remaining in them completely evaporates).

The procedure must be carried out carefully, cleaning and removing all dirt and plaque present on the surface. remember, that washed and cleaned candles work 10-15% more efficiently than dirty ones.

Results

The appearance of a black spark plug on a carburetor or injector can be caused by various reasons. usually several of them. For example, incorrectly selected candles, prolonged operation of the internal combustion engine at high speeds, incorrectly set ignition, faulty valve stem seals, and so on. Therefore, we recommend that you, when the symptoms described above appear, simply periodically check the condition of the spark plugs on your car.

Inspect and clean the candles at every oil change (8 - 10 thousand km). It is important that the correct gap is set, and the spark plug insulator is clean. It is recommended to replace candles every 40 ... 50 thousand kilometers (platinum and iridium - after 80 ... 90 thousand).

So you will not only extend the life of the internal combustion engine, but also maintain power and driving comfort. You can see additional information on how to diagnose a car's internal combustion engine by the color of soot on spark plugs.