Causes of black carbon deposits on carburetor spark plugs

Black carbon deposits on spark plugs, causes

Black carbon deposits on the electrodes and insulators are one of the most common spark plug problems.
Its appearance indicates certain problems in the operation of the car engine and its systems. In most cases, black soot is the remnants of an over-enriched fuel mixture that have not burned in the combustion chamber. Constant use of spark plugs with black soot leads to interruptions in their operation at best and complete failure at worst. This is reflected in engine operation by the appearance of dips and jerks, unstable idling (the engine “troits”), “shooting” at the muffler, loss of power and throttle response, and increased fuel consumption.

There are not so many reasons for the appearance of black carbon deposits on the spark plugs of a carburetor engine of a passenger car (for example, VAZ 2108, 2109, 21099, 2105, 2107). Below is a list of them in relation specifically to carburetor engines of VAZ 2108, 2109, 21099, 2105, 2107.

Reasons for the appearance of black carbon deposits on the spark plugs of a carburetor engine

— Reasons related to the carburetor and power system

Black carbon deposits on spark plugs are the result of a highly enriched fuel mixture, the residues from incomplete combustion of which are deposited on the electrodes and insulator of the spark plugs. This can lead to:

Increased fuel level in the carburetor float chamber (“overflow”)

The level is not adjusted correctly, the needle shut-off valve is not sealed, the float(s) are not sealed, the float(s) touches the walls of the float chamber, the fuel pump creates excess pressure (the drive pusher protrudes strongly).

Measuring the fuel level in the float chamber of the carburetor 2108, 21081, 21083 Solex

Measuring the protrusion of the VAZ fuel pump pusher

Wear or leakage of the power mode economizer ball valve

Excess fuel enters the engine not only in power modes, when the economizer should be turned on, but also in all other modes.

Economizer device for power modes of carburetor 2108, 21081, 21083 Solex

Clogged air jets of the main dosing systems

The fuel mixture becomes over-rich because not enough air is supplied to it.

Air jets, fuel jets, emulsion tubes and GDS wells of the Solex carburetor

The fuel mixture “quality” screw is not adjusted correctly

The adjustment was made in the direction of re-enrichment of the fuel mixture.

Screws for adjusting the “quality” and “quantity” of the fuel mixture of the Solex carburetor

The air filter is very dirty

In this case, the balance of fuel and air again shifts towards an excess of fuel.

Heavily contaminated car engine air filter element

— Reasons related to the ignition system

The ignition timing is not set correctly

Most likely the ignition is too early. The fuel mixture ignites too early and does not burn completely.

Ignition alignment mark on flywheel

The high-voltage wires, the cover or the “slider” of the distributor are “broken”

Current leakage through “broken” parts of the ignition system reduces the power of the spark or leads to its termination. The fuel mixture does not burn efficiently.

Ignition coil is faulty

The ignition coil may leak current through a crack in the cover. The consequences are similar to those described above.

The spark plugs themselves are faulty

The glow number of the spark plugs does not correspond to the engine, the gap between the spark plug electrodes is small, the spark plug is internally defective.

The listed malfunctions lead to interruptions in spark formation, a weak spark between the electrodes of the spark plugs and, accordingly, to poor and inefficient combustion of the fuel mixture. As a result, the engine “troubles” or does not start, the electrodes of the spark plugs are black.

— Reasons related to engine malfunction

Severe wear on piston rings

There is no compression in the cylinders on the compression stroke. Without the necessary pressure in the combustion chambers, the fuel mixture burns poorly and deposits black soot on the spark plugs.

Problems with the engine valve train

The valves are not sealed and their thermal clearances are not adjusted.

These reasons lead to inefficient combustion of the fuel mixture, its burning out in the intake manifold and, accordingly, the deposition of black deposits on the electrodes of the spark plugs.

Notes and additions

— If the engine and all its systems are operating normally, carbon deposits on the spark plugs are brown (the range of brown can be from light brown to dark brown).

Causes of black soot

Before finding out the reason why the candles turned black, it is important to understand how this happened, how many of them turned black (one, two or all at once), on which side the soot formed (on one, two or all around), how “dry” it is. or "wet".

This determines how to diagnose and what to pay attention to first.

It is also important to understand that some malfunctions contribute to the rapid formation of black soot and affect its character, and some chronic engine problems can change the condition of the spark plugs gradually.

But before you indulge in various breakdowns, make sure:

Is the idle speed set correctly, especially for carburetor engines?
Are you driving the car correctly, are you not overloading the engine with high speeds, what is the cruising speed on a flat road. Those. It is important to make sure that the machine was operated as correctly as possible and the spark plugs worked in their optimal mode.
If the conditions listed in paragraph 2 are met, the appearance of the first slight deposit on new spark plugs will occur after 150 - 200 km. If earlier, and it is clearly black, then you should sound the alarm.
Where do you refuel and what kind of fuel do you put in the tank? If you often drive on gasoline, then don’t be surprised by black spark plugs, but you won’t be able to really find out why they became that way. Also, in the cylinder, at a temperature of about 5000C, low-quality gasoline does not burn completely, which also causes black soot on the spark plugs.

Causes of soot:

Late ignition - uniform black carbon deposits form on the spark plug.
Malfunctions in the ignition system (carburetor engine). The following malfunctions can lead to incomplete combustion of fuel in the cylinders as a result of a weak spark or to failures in its formation and, as a result, the appearance of black soot, these are: faulty ignition coil and spark plugs themselves, poor insulation of high-voltage wires, ignition angle is set incorrectly, breakdown of the distributor runner and the cover itself.
Valve burnout. Carbon deposits can form on both the side and bottom electrodes, i.e. from a certain side. Also, incorrectly adjusted thermal valve clearances can lead to incomplete combustion of fuel in the cylinders and, as a result, the appearance of carbon deposits on the spark plugs.
Enriched air-fuel mixture. This case is characterized by a black velvety soot without oil stains.

Applies to both carburetor and injection engines. As for the first, the formation of black carbon deposits on the spark plugs can be influenced by: the float touching the chamber walls or its depressurization, incorrect fuel level in the carburetor, a strongly protruding fuel pump drive pusher, which creates high fuel pressure in the system, or a depressurized needle valve. As for the injector, pay attention to the condition of the injectors, which, as a result of depressurization, can constantly flood the spark plugs with fuel. And also on the MAF (mass fuel flow sensor). It analyzes the mixture and sends data to the ECU. If it is faulty, the ECU will give incorrect commands to the injectors.
Incorrect heat rating. One of the criteria for choosing spark plugs is the heat rating. The higher it is, the less the candle heats up and vice versa. A spark plug with an incorrectly selected heat rating for a particular engine may not only blacken unevenly, but also fail.
Low compression. In the cylinder where the black spark plug was found, check the compression.
The power mode economizer ball valve (for carburetors) has failed. As a result of this malfunction, a large amount of fuel enters the cylinders even when it is not needed, for example, during normal engine operating conditions.
High pressure in the fuel rail (for injectors). Fuel regulator is broken.
The air damper actuator and air filter have failed. Check the latter and replace if necessary.
Notice the smoke coming from the exhaust pipe.

If the engine is running on a rich fuel mixture or late ignition is observed, this will manifest itself:

High level of engine vibration as a result of its unstable operation, especially at low speeds.
The appearance of error P0300 on the instrument panel of an injection car and misfires on the carburetor.
Poor engine starting.

The most dangerous thing for spark plugs is oil getting on them and simultaneously overheating. This will lead not only to their rapid blackening, but also to failure of the electrodes - they cannot be repaired.

Possible reasons for the appearance of soot

Before answering the question of why the candles are black, you need to decide how exactly they turned black . After all, it depends on which direction to search. In particular, the candles can turn black all together, or maybe only one or two of the set. Also, the candle may turn black only on one side, or perhaps along its entire diameter. There are also so-called “wet” and “dry” carbon deposits.

It should be noted that the speed of appearance and nature of carbon deposits directly depends on existing faults (if any):

Carbon deposits on new spark plugs begin to form after at least 200-300 km. Moreover, it is advisable to drive along the highway at approximately the same speed and engine load. This way the spark plugs will work in optimal mode, and it will be possible to more objectively assess the condition of the car’s components.
The amount and type of soot depends on the quality of the fuel used. Therefore, try to refuel at trusted gas stations, and not drive with gasoline or similar mixtures. Otherwise, it will be difficult to establish the real cause of the appearance of soot (if it occurs).
In a carburetor engine, the idle speed must be set correctly.

Now let's move directly to the question of why black soot appears on the spark plugs. There may be 11 main reasons :

If you notice blackening on only one side, then most likely this is caused by a burnt-out valve. That is, carbon deposits on the spark plug fall on the side electrode from below (and not on the central one).
The cause of black spark plugs may be a burnt-out valve. The situation is similar to the previous one. Carbon deposits may penetrate the bottom electrode.
An incorrectly selected glow rating of a spark plug causes not only damage to it during further use, but also uneven blackening at 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.

“Dry” carbon deposits on a candle

As a rule, when the ignition is set late and the air-fuel mixture is rich, the following consequences arise:

misfires (error P0300 appears on injection engines);
problems starting the engine;
unstable engine operation, especially at idle, and as a result, increased vibration levels.

Next, we will tell you how to eliminate the listed faults and how to clean the spark plugs.

Causes of deposits

It is impossible to determine them completely by the type of candle. This is just a reason for the appearance of a working version, which will then need to be confirmed by instrumental diagnostics or other repair methods.

Rich mixture

For combustion without residue, the mixture must meet certain limits in terms of the ratio of oxygen and gasoline vapors in it. And not only in steady, stationary mode, but also in transient modes, that is, during acceleration, warming up, engine braking, idle and power modes. There may be not enough oxygen or there may be a slight excess, but in any case, during normal engine operation, the spark plugs should not turn black. The appearance of black soot on the spark plugs indicates incomplete combustion of fuel, which means either too much of it is supplied, or there are difficulties in supplying the required amount of air.

The reasons for abnormal over-enrichment of the mixture can be very diverse:

overflow nozzle or misregulated carburetor metering system;
air filter clogged with dust;
incorrect operation of sensors or oxygen feedback of the engine management system;
abnormal pressure in the fuel rail;
the consequences of illiterate tuning when trying to get an increase in power by simply enriching the mixture.

In this case, the candle will be evenly covered with a velvety black coating of classic soot, most reminiscent of uncleaned stove heating chimneys. And since pure carbon is an excellent conductor of electricity, the energy of the spark will flow through this graphite, and the ignition will stop.

Poor self-cleaning

The candle must be in thermal balance mode, that is, have a temperature of the insulator and electrodes at which the soot that falls on them burns out in the presence of oxygen. If the temperature is insufficient, then even the presence of an oxidizing agent will not help. This happens if the engine is loaded without allowing it to warm up. In power mode, the mixture is enriched, carbon particles are released, fall on the candle, and do not have time to burn out. If you do not allow sparking to occur, then eventually the temperature will rise and the excess soot will successfully burn.

But it is quite possible that the interruptions will begin earlier, the temperature will drop even more, the spark plug will fail, and the owner will be presented with black spark plugs, the reason for which is similar to the previous case.

Heat number discrepancy (CN)

It is the CN that determines the operating temperature of the spark plug, being responsible for both its anti-knock properties and self-cleaning. This number cannot be increased, since too hot electrodes will become a source of abnormal combustion, and it is undesirable to lower it due to the tendency of the spark plug to be filled with hydrocarbons. Therefore, the CV is very carefully selected for each specific engine on stands and is indicated in the form of a recommended type of spark plug or its analogues with the same properties. Ignoring these requirements is fraught with problems, even destruction of the engine. Well, a spark plug that is simply “cold” for a given engine will quickly become covered with unburned carbon. Sometimes completely, and sometimes - separately the electrodes or only the upper part of the insulator. It is always colder because it is in contact with the body and is located further from the combustion source.

What to do if soot appears

First of all, it is necessary to remember that oil contamination and overheating, which results in soot on the spark plugs, are very harmful to the ignition system . Overheating is especially dangerous, since it causes the possibility of failure of the electrodes on the spark plugs without the possibility of their restoration.

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

Oil deposits

In some cases, the candles may be wet and black. Most often, the reason for this fact is oil getting into the combustion chamber. Additional symptoms of this problem are as follows:

difficulty starting the engine;
omissions in the operation of the corresponding cylinder;
the engine jerks during operation;
the appearance of 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 a major engine overhaul . In rare cases, you can get by with decoking the engine. If oil enters the combustion chamber through the top, it comes from the cylinder head along the valve guides. The reason for this is the wear of the valve stem seals. To eliminate this problem, you just need to select new, high-quality caps and replace them.

Carbon deposits on the insulator

Red carbon deposits on a candle

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

If black and red spark plugs , this means that you are pouring fuel with an excessive amount of metal additives. It cannot be used for a long time because over time, metal deposits form a conductive coating on the surface of the spark plug insulator. Sparking will deteriorate and the spark plug will soon fail.

Cleaning spark plugs

Black spark plugs VAZ 2110 - how to fix the problem

If you notice black carbon deposits on the spark plugs, it is advisable to contact qualified specialists. They will be able to identify the cause and fix the problem. Fans of self-repairs of the “iron friend” should remember if carbon deposits appear on the spark plugs and whether the time has come to replace the air filter. If it is clogged, deposits will certainly appear, since the remaining air-fuel mixture is not removed in a timely manner. You will also have to start cleaning the carburetor and injector. These units are designed to control the ratio of ingredients in the fuel mixture that is supplied to the spark plugs. If they are dirty and malfunction, the ignition system also becomes clogged and receives an excessive amount of oil. Violations may not be due to clogging of carburetors or injectors, but to poor-quality adjustments. Therefore, it is worth turning to professionals who will carry out high-quality adjustments.

The most dangerous moment is the appearance of oil deposits on the spark plugs. If lubricant enters the combustion chamber from above, the oil seals must be replaced. This repair is inexpensive and can be done quickly. If oil penetrates through the piston rings, a major overhaul of the car's engine will be required. It is unlikely that you will be able to do this kind of work yourself.

Cleaning spark plugs from deposits

Cleaning candles must be done regularly, as well as inspecting their condition. It is recommended to do this after approximately 8.10 thousand kilometers . It is very convenient to do this when changing the engine oil. However, if the symptoms described above occur, you can do this earlier.

it is not recommended to use the old method of using sandpaper to clean electrodes . The fact is that this creates a risk of damaging the protective layer on them. This is especially true for iridium spark plugs . Their central electrode is thin and coated with iridium, which is a semi-precious and rare metal.

To clean spark plugs you will need:

detergent to remove plaque and rust;
disposable plastic cups (after completion of the cleaning procedure they must be disposed of; they cannot be used for food products in the future);
a thin brush with hard bristles or a toothbrush;
rags.

The cleaning procedure is performed according to the following algorithm:

The cleaning agent is poured into a glass prepared in advance to a level that completely immerses the spark plug electrodes (without an insulator).
Immerse the candles in the glass and leave for 30-40 minutes (during the process, a chemical cleaning reaction occurs, which can be observed with the naked eye).
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, especially paying attention to the electrodes.
Wash the candles in warm running water, removing the chemical composition and dirt from their surface.
After washing, wipe the candles dry with a rag prepared in advance.
The final stage is to dry the candles on a radiator, in the oven (at a low temperature of +60...+70°C) or using a hairdryer or fan heater (the main thing is that the remaining water 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 are 10.15% more effective than dirty ones .

Results

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

This way you will not only extend the life of the engine, but also maintain power and driving comfort. You can see additional information on how you can diagnose a car engine by the color of spark plug soot.

Marks on spark plugs

Faults can be indicated by marks formed on the parts.

They can be:

oil;
ash;
gasoline;
in the form of erosion.

Oil traces

The absence of deposits on the structure of the electrode component and the appearance of traces of motor fluid indicate that parts of the motor have begun to deteriorate. While driving, the power unit will lose power and tripping will begin. The consumption of fuel and engine fluid may increase, and after starting the engine, white-blue smoke will come out of the muffler for several minutes. The appearance of oil traces on the electrodes is associated with malfunctions of the valves or piston rings.

The Krichushkina kopilka channel talked about the causes of soot in the North West.

Ash traces

The appearance of ash deposits on the electrode component indicates that the lubricant has entered the combustion chamber of the internal combustion engine. There may be no carbon deposits, but if there is one, then its color shade does not matter. The problem is related to the exhaustion of the cylinder or the occurrence of piston rings. This leads to increased consumption of engine fluid, resulting in blue smoke coming out of the muffler.

Traces of fuel

If there are traces of fuel on the SZ, the problem must be looked for in the car’s engine. The problem may be ignition timing because the spark is supplied to the spark plugs earlier. As a result, unburned fuel residues remain on the spark plugs. Sometimes the problem appears after a cold start of the internal combustion engine or in winter, at low negative air temperatures. The fuel does not have time to evaporate.

A thick soot deposit may form on the insulator itself and the electrode components. The color of the soot does not matter; it can be black or whitish. The problem may indicate the destruction of the partition located between the rings, and the elements themselves are destroyed as a result of working out. This leads to engine fluid burning out and settling inside the power unit, in particular in the SZ. If, in addition to traces of fuel, destruction of the insulating device or electrode component is observed, then the problem may lie in the use of defective parts.

Other reasons:

early detonation of the power unit, ignition adjustment required;
incorrectly adjusted valve timing;
refueling with low-quality fuel;
Ignition is set early.

Signs of trouble:

the car's engine began to stall;
there were knocks when the engine was running and other extraneous sounds that were uncharacteristic of its operation;
increased consumption of motor fluid and fuel;
traction decreased when driving;
Blue smoke comes out of the exhaust pipe.

Erosion NW

The formation of erosion may be associated with the development of parts and long-term use of a car with such spark plugs. Sometimes the cause is regular refueling of the car with fuel that contains tetraethyl lead particles. To eliminate the problem, parts are replaced and fuel is changed.

Main symptoms of problems:

instability of the car engine at idle speed;
drop in engine power while driving;
tripling of the power unit.

Black carbon deposits on spark plugs on a carburetor engine - causes

When black carbon deposits are detected on spark plugs, every car owner must understand and find out the cause of the occurrence and what malfunctions appeared in the car. And the most common malfunction can be considered the use of low-quality fuel for a long time, a malfunction in the ignition system, an incorrectly adjusted carburetor internal combustion engine and a mismatch of the hot-air system. Diagnosing these problems is very easy; just look at the blackened spark plugs.

What could be the reasons for the appearance of dark soot on candles?

First, you need to determine what caused the blackening of the candles.
After all, this may directly depend on which direction the car owner moves in order to subsequently discover the exact cause. They can turn black either all at once or individually. When clarifying, it is worth considering how quickly this happens and the immediate nature of this phenomenon. On completely new spark plugs, carbon deposits begin to appear as if only a little after two hundred to three hundred kilometers of the vehicle. In this case, it is best to travel along the highway with the same speed limit, so it will be much easier to detect malfunctions.

The amount and type of carbon deposits formed directly depends on the quality of the fuel poured into the gas tank. There is no need to experiment and refuel your car at different gas stations each time. As a result, it simply will not be possible to correctly assess and accurately detect the obvious cause of the appearance of soot.

There are several main reasons why soot forms on them:

If in the end blackening is noticed only on the 1st side, then this is more than likely caused by a burnt-out valve. In this case, carbon deposits on the spark plugs fall from below onto the side electrode and not onto the central electrode.
In a situation where incorrectly selected spark plugs can cause not only damage during operation, but also uneven darkening.

The heat number is a value that characterizes the time it takes for it to reach ignition. If a large potassium number is indicated on it, then it will heat up less. When uniform carbon deposits appear on the spark plugs, it indicates that delayed ignition is occurring.

The appearance of black spark plugs on a carburetor engine can be caused by the following factors: the fuel level was not adjusted correctly, the needle shut-off valve is depressurized, the fuel pump creates excessive pressure, the float is depressurized.

Black carbon deposits on VAZ 2109 spark plugs: causes and solutions

By the appearance of the VAZ 2109 spark plugs, you can check how the car’s power system is configured and estimate fuel consumption. Since the VAZ 2109 spark plug is screwed directly into the engine cylinders, it interacts with the combustible mixture while the engine is running.

Everyone knows that while the VAZ 2109 engine is running, at different moments the power system (carburetor or injector) supplies a different combustible mixture: when starting the engine, the mixture is over-rich, when idling, when the car is coasting, it is lean.

However, when the engine warms up to operating temperature, the gasoline-to-air ratio remains approximately at the same level. This level is 1 to 15, that is, in the sprayed combustible mixture there are fifteen grams of air per gram of gasoline. If configured correctly, when you do so, it should have a golden color.

Yes, when the engine starts and warms up, it turns black, but as it warms up and after half an hour of operation on a warm engine, it cleans itself. The standard is a golden-colored spark plug, which means that the carburetor or injector produces an optimal combustible mixture in its composition and it burns completely in the cylinder.

This is a wake-up call for the owner of the car - it is more expensive to operate and runs the risk of not passing the next technical inspection due to exceeding the CO CH toxicity level.

There are few positive aspects in a rich combustible mixture, but they exist - the VAZ 2109 is more playful and responsive. The mixture is rich, so the engine power increases and the car becomes more nimble.

Remove the high-voltage wire from this spark plug and bring it to ground. Crank the starter, if the spark jumps and it is stable and powerful, then it is necessary to replace the spark plug. If a spark does not appear or is weaker than on neighboring cylinders, replace the high-voltage wire and clean the contacts on the ignition distributor cover.

There is more air in the combustible mixture than necessary. This may be due to too low a level of gasoline in the float chamber of the carburetor, insufficient operation of the fuel pump, or due to incorrect adjustment of the carburetor or incorrect operation of the control unit for injection engines. In this case, the VAZ 2109 accelerates slowly and tries to stall when starting off, that is, the engine does not develop its full power, but this reduces fuel consumption.

As can be seen from what has been written, with such a simple action as unscrewing the spark plug from the VAZ 2109 engine, you diagnose the engine yourself and can find some problems in its operation.

The main reasons why spark plugs turn black in a VAZ 2109

The main reasons why spark plugs turn black in VAZ 2109 and 21099 cars I would include the following points:

Refueling with low-quality gasoline (most often mixed with diesel fuel). It happened once when I poured more than 20 liters of gasoline and managed to burn it in just 100 km along the highway. Smoke poured out of the exhaust pipe like from a tractor. The reason is that the fuel was mixed with diesel! So, this happens with us too.
Engine oil gets on the spark plug electrodes. This can happen in several cases. The first is wear of the valve stem seals. The second is excessive wear on the piston rings. In both cases, repairs are necessary, since it is simply impossible to prevent oil from entering the combustion chamber in any other way.
The gap between the valves and the guide sleeve is too large. In this case, even replacing the valve seals will not help solve the problem. And the only way is
change guide bushings

Solutions to the problem

Based on the problems described above, the appearance of black soot on candles can be solved in the following ways:

Replacement of valve stem seals and piston rings.
Replacing guide bushings
Change gas station

Well, in general, blackening candles is a sign of a malfunction in the fuel system or car engine, so my personal recommendation is to take this problem more seriously.

Video why candles turn black

Significant wear and depressurization of valve floats

In simple terms, this fuel begins to flow in large quantities into the internal combustion engine of the internal combustion engine in normal and powerful modes.

Clogged air filter

It may also cause darkening of the spark plugs. It needs to be checked and, if anything, replaced with a new one.

Ignition system: the ignition angle is incorrectly set, the insulation of the wires is damaged, the integrity of the cover and the thrombler slider is damaged, then the ignition coil is not working properly and in the end it’s all about the spark plugs themselves.

All of the above reasons can lead to inconsistent sparking, in which case not only gasoline combustion occurs, but also coal-black soot appears on the spark plugs.

Burnt out valves (ICE)

Very often, valves burn out or the gaps are not adjusted correctly.

This also results in carbon deposits on the spark plugs.

A black spark plug corresponds to a reduced compression ratio in the cylinder.

What consequences may arise with late ignition and full operation on a rich hot-air mixture: inconsistent ignition, difficulties in starting the internal combustion engine, unstable operation.

Reasons for the formation of black soot

So why are spark plugs black? The accuracy of determining the causes of soot entirely depends on the analysis of its structure. The main forms of soot are dry (soot) and oily.

Experts believe that the main reason for the formation of black soot deposits is excessive enrichment of the fuel mixture. A motorist who is concerned about the condition of his car’s spark plugs simply needs to know the factors influencing increased enrichment of the fuel mixture:

Malfunctions or incorrect carburetor settings.
Due to a lack of oxygen flow due to a clogged air filter, complete combustion of the fuel mixture does not occur.
Problems with the starting enrichment.
The presence of increased pressure in the fuel rail (for injection power plants) contributes to excessive fuel injection. Occurs due to malfunctions of the fuel pressure regulator.
Low compression value in one or more cylinders.
Weak spark.

However, excessive enrichment of the air-fuel mixture is not the only answer to the question: “Why are spark plugs black?” There are several other reasons that influence (albeit to a lesser extent) the coating of spark plug electrodes with black soot. Here they are:

Malfunction of the ignition coil.
The air filter element is clogged.
Increased (reduced) gap of the breaker-distributor.
Capacitor failure.
Incorrect operation of the injection system.

Another reason that leads to the appearance of black carbon deposits on automobile spark plugs and requires immediate elimination is the installation of spark plugs whose heat rating does not correspond to the parameter specified by the manufacturer. In this case, two options are possible:

unburnt remains of the fuel-air mixture settle on the spark plug elements, forming a coating;
The spark plug heats up under the influence of high temperatures, and the power unit begins to operate in glow ignition mode.

If the carbon structure shows signs of oiliness, then the car owner receives direct evidence of excess oil entering the combustion chamber. The main reasons for the formation of oily deposits on the spark plug electrodes are excessive wear:

oil valve caps;
oil scraper piston rings.

How to fix the above problems?

What to do if black soot appears on the candles.

Firstly, it is necessary for every car connoisseur to remember that oil contamination and excessive heating are all the result of the accumulation of soot on the spark plugs themselves. In this case, it will be very scary if overheating was allowed before. After all, it is precisely because of this that the electrodes on the spark plugs go out of their working condition.

One of the previously installed spark plugs may also begin to leak. And it’s very easy to understand which one exactly caused the wiping; in this case, they should be swapped. And if, after such a simple diagnosis, the new spark plug also darkens, and the old one looks as if it had just come from the store, the malfunction will immediately become clear, then the problem is not in the spark plugs themselves, but in the cylinder.

And if during such a diagnosis nothing has changed, then in such a situation it is necessary to raise the question of the performance of these same candles.

Solutions to the problem

Based on the problems described above, the appearance of black soot on candles can be solved in the following ways:

Replacement of valve stem seals and piston rings.
Replacing guide bushings
Change gas station

Well, in general, blackening candles is a sign of a malfunction in the fuel system or car engine, so my personal recommendation is to take this problem more seriously.

Spark plugs are installed in a car to perform two functions - ignition of the working mixture in the combustion chamber and removal of excess heat after detonation. Their competent operation seriously affects the traction properties of the engine, and if the engine begins to operate unstably at idle, with difficulty, you should pay attention to the condition of the spark plugs.

How to clean spark plugs from carbon deposits that have formed on them?

This procedure should be carried out as often as possible and it is also necessary to directly inspect them and check their condition. Most specialized experts recommend doing this as regularly as every eight to ten thousand kilometers.

People who have already had to deal with cleaning candles can only be advised not to resort to this option - this method greatly damages the electrodes. This is especially worth considering if the engine has iridium spark plugs. The central electrode in them is quite thin, and the coating is iridium (this is a rare type of iron and is considered valuable).

For cleansing you will need the following things:

A product for removing rust and plaque;
Plastic glass;
Brush for cleaning teeth;
Unnecessary rags.

Algorithm for cleaning spark plugs from carbon deposits

You need to pour water into a previously prepared plastic glass and immerse the candle electrodes in it.
Next, they need to be left for a short time, about thirty to forty minutes.
At the end of the holding time, they are subsequently removed and all accumulated plaque is removed with a toothbrush.
Then they are further washed under central running water and finally wiped with a rag.
The final step is to dry the clean spark plugs, if for this you choose the option with an oven in which a special temperature is set at sixty to eighty degrees.
You must place a container of water at the bottom so that it evaporates completely.

The main reasons why spark plugs turn black in a VAZ 2109

The main reasons why spark plugs turn black in VAZ 2109 and 21099 cars I would include the following points:

Refueling with low-quality gasoline (most often mixed with diesel fuel). It happened once when I poured more than 20 liters of gasoline and managed to burn it in just 100 km along the highway. Smoke poured out of the exhaust pipe like from a tractor. The reason is that the fuel was mixed with diesel! So, this happens with us too.
Engine oil gets on the spark plug electrodes. This can happen in several cases. The first is wear of the valve stem seals . The second is excessive wear of the piston rings . In both cases, repairs are necessary, since it is simply impossible to prevent oil from entering the combustion chamber in any other way.
The gap between the valves and the guide sleeve is too large. In this case, even replacing the valve seals will not help solve the problem. And the only way is to change the guide bushings

Black carbon deposits on spark plugs: causes

SZ installed in a car perform two main functions - ignition of the fuel mixture and removal of excess thermal energy after detonation. In addition, it is the spark plugs that are an indicator of the correct operation of certain components of the car. Their good condition affects the power of the power unit. If the engine is idling unstable, the start is delayed, or a “twitching” sensation is felt, it is advisable to check the spark plugs. The urgency of replacing elements is indicated by deformation of the product, chips and soot on the elements. The reasons for its formation are different, we will talk about this further.

Black soot on the NW

Spark plugs covered in black soot. Why?

Black carbon deposits in the spark plugs indicate a lean fuel mixture and fuel overflow occurs. Gasoline consumption has been increased.

The concept of a lean, rich mixture is explained simply - the fuel is enriched with air, and depleted with gasoline. With black carbon deposits, the mixture has an excess of fuel, and a lack of air - if the problem is in the fuel system of the car.

Plugs with black carbon deposits from electronic fuel injection systems are repaired by an auto diagnostician. The mechanic connects the laptop to the controller, looks at the indicators of the quality of the mixture and ignition. The price of diagnostics for domestic cars is from 500 rubles.

Cars with a mechanical fuel injection system (carburetors) are more difficult to repair. Requires knowledge of the operation of carburetor systems, consisting of many small parts. Carburetor repairs are carried out in a carburetor workshop. There are few specialists left in this field; carburetor cars have outlived their time.

Candles are covered with white soot.

A white soot coating on the spark plugs indicates a rich fuel mixture. The amount of air in the mixture exceeds the norm. Fuel consumption has been reduced.

Reduced fuel consumption will not please you in this situation. Operating a vehicle with white carbon deposits is prohibited.

There is a high load on the main engine parts.

The problem of white carbon deposits is eliminated at auto diagnostics in a carburetor workshop.

Carbon deposits on spark plugs are easy to clean.

Cleaning spark plugs will take a short time, 10-20 minutes.

The procedure for cleaning carbon deposits is performed on a cold engine and looks like this:

1. Buy a spark plug wrench. Unscrew the spark plugs.

2. Buy a special metal brush, sold in the markets.

3. Wearing gloves, clean the spark plugs with a brush.

4. The electrodes are thoroughly cleaned. Cleaning is carried out until the carbon deposits are completely removed.

5. Clean the candle skirt.

6. Check the gap between the electrodes of the spark plugs - it should be the same!

1.0 - 1.13 mm for injection engines. 0.7 - 0.8 mm for carburetor engines.

7. The spark plugs should be tightened strictly on a cold engine! Otherwise, there is a risk of easily stripping the threads on the cylinder block!

Frequency of replacement of ignition elements

Automakers provide specific recommendations on how often spark plugs need to be checked and replaced. Let us clarify that the data indicated in the technical documentation is somewhat exaggerated by the manufacturer, and motorists are forced to change them more often than stated. If you suspect wear or poor condition of the spark plugs, you can determine their condition quite easily by carefully examining the shade of soot formed on the surface of the electrodes. This allows you to determine which systems and components of the vehicle lead to incorrect operation of the elements.

Formation of soot on the surface of SZ electrodes

Car enthusiasts often ask the question: “ Why is there black soot on the spark plugs and soot of a different shade forms?” It's simple - spark plugs are used under conditions of aggressive thermal and chemical influences. In particular, when burned, the working mixture forms a grayish coating on the electrodes and this is a sign of the correct operation of all systems. And black spark plugs, as well as white or red soot, are not only a warning about urgent replacement of spark plugs, but also about the advisability of promptly diagnosing the engine for failures and breakdowns.

The nature of the deposit will tell you about the causes of malfunctions

The shade of soot on the electrodes of the elements is a clear signal of what kind of failures in the power unit could lead to this. This is often due to the fact that sparking does not occur correctly, the composition of the fuel used or the temperature indicator inside the combustion chamber does not meet the requirements. We will tell you why the candles turn black later.

Checking the condition of the power unit by carbon deposits

Automotive ignition elements remain a good diagnostic indicator if you need to identify problems with the ignition cycle of the fuel mixture. But you should not make an unambiguous conclusion about the condition of the power unit by inspecting the SZ after 25 or more than 1000 km of run. Diagnostics should be carried out exclusively on new products, after a short run-in (150-200 km).

Checking the SZ for the presence of black soot

To check for malfunctions in the power unit based on the soot formed, you need to:

Supply new elements in accordance with technical specifications.
Travel 200 kilometers with them.
Remove the SZ and look at the shade of soot that appears on them.

Important! It is necessary to check the color of the deposits formed on the elements only on a warm engine.

Varieties of black soot

The black color indicates the presence of ordinary soot on the candle, that is, unburned amorphous carbon. It is produced by petroleum products and other organic matter that have failed to oxidize properly.

A more accurate assessment of the situation is determined by both the shades of color and the nature of its distribution over the working part of the candle. The appearance of any belts around the outer part of the insulator, located above the hexagon under the spark plug wrench, is usually not a cause for concern, although many auto repairmen mercilessly reject good spark plugs for this very reason. At the very least, this is not justified.

Uniformity of carbon deposits. It can be concentrated only on the metal of the electrodes, lie on the insulator on one side, or have a location in the form of a cone going deep into the body. As if revealing the source of its appearance in the form of uneven carbon flow or temperature changes along the insulator.

External dryness of soot. It may look slightly damp and even have a different smell, for example, a strong smell of gasoline. There should be no gasoline remaining in a properly functioning cylinder.

Oiliness. The porous carbon structure is easily impregnated with oil, and is often formed from it. There are always oil vapors in the combustion chamber, but normally their amount is negligible, and they burn out instantly.

“Velvet” type of soot. This indicates its large-pore structure, that is, rapid formation and increase in volume.

The opposite situation is a dense, even possibly shiny deposit. It accumulates for a long time, is durable and does not have a radical black tint.

Combination of black with other colors. For example, red or brown.

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Such nuances indicate various causes of problems. If you rely on them when diagnosing, you need to make sure that the formations are stable and did not accidentally appear a minute ago. To do this, the engine must at least be warmed up, or better yet, loaded with tens of kilometers of movement at a fairly high speed.

The nature of the deposit will tell you about the causes of malfunctions

Black carbon deposits on spark plugs

When removing a spark plug for diagnostics, the car owner usually sees black spark plugs . Unfortunately, based on the appearance of such deposits, it is not always possible to correctly identify specific breakdowns. Black soot on the SZ is expressed in various ways, for its part, it indicates certain malfunctions in the engine. The different structure of soot will accurately indicate the category of problems arising in the power unit.

Remember! The uniform distribution of coffee/grayish soot indicates the absence of problems with fuel combustion. This deposit will be a clear sign of high-quality and proper operation of the engine.

Let's look at the main variations of black carbon deposits on ignition elements:

Soot with an oily structure

Black carbon deposits with an oily structure , present on the threads and surfaces of the electrodes, often appear in combination with an additional feature - the bluish color of the exhaust smoke when the power unit is started. This type of soot on the SZ indicates that there is excess oil in the combustion chamber.

Oily soot on NW

This is a consequence of high wear of the following parts:

Piston oil seal.
Piston valve rings.
Valve guide bushing.

From this it is obvious that the problem lies in the wear of parts of the piston system. When such a symptom appears, replacement of worn-out components is required.

Black deposits similar to soot

Another type of black soot on elements is called “velvet.” This type of soot does not have oily smudges. This type of soot indicates that an overly enriched working mixture is leaking into the combustion chamber. Let's look at the reasons for the formation of sooty black deposits in different types of engines (carburetor/injector).

Black soot-like deposits

Carburetor power unit

The cause of soot in the NW is very often excessively enriched fuel. It, without burning completely, settles on the electrodes. This is often caused by:

unstable operation or incorrect carburetor settings;
problems with electric valves;
engine cylinders have low compression levels;
dirty or malfunctioning air filters;
weak spark.

All of the above malfunctions are typical, including for cars such as the VAZ-2107 (carburetor) and all others.

Injection engine

The reason for the formation of black carbon deposits on the injector is due to increased pressure in the fuel frame. This leads to excess supply of the fuel mixture. In this case, the pressure stabilizer does not work correctly.

Other causes of black candles

malfunction of the ignition coil or incorrect setting of the advance angle;
high wear of valves, piston rings or condenser;
The products themselves have faults.

Why there is black soot on the spark plugs: reasons

Black carbon deposits on spark plugs may cover all spark-producing elements or appear only on some of them. If one element turns black, this can be associated with its malfunction. Sometimes the wire in the spark plug just burns out. But a malfunction of the cylinder corresponding to this element cannot be ruled out.

If the element is covered with soot on only one side, this indicates a poor valve fit. Also, the reasons may be a burnt-out valve or problems with the timing belt.

Uneven formation of soot is caused by a mismatch between the heat rating of the spark plug and the type of engine. If the CN of an element exceeds the established norm, only its upper part will become dark, and the body will remain white. With a low heat number, on the contrary, the color of the body will change.

When all the elements turn black at once, this is a consequence of late ignition. In this case, it is recommended to listen to the starter. If the ignition is really late, the starter makes sounds similar to knocking.

Also check the operation of the injector. If it malfunctions, the TV mixture may become excessively rich. As a result of the combustion of such fuel, a black coating is obtained. Its appearance is also associated with the following malfunctions:

clogged air filter;
incorrect ignition angle;
damage to wiring insulation;
deformation of the distributor runner or its cover;
ignition coil defect.

Let us summarize the reasons for the appearance of carbon deposits on different types of engines.

Carburetor power unit

The cause of soot in the NW is very often excessively enriched fuel. It, without burning completely, settles on the electrodes. This is often caused by:

unstable operation or incorrect carburetor settings;
problems with electric valves;
engine cylinders have low compression levels;
dirty or malfunctioning air filters;
weak spark.

All of the above malfunctions are typical, including for cars such as the VAZ-2107 (carburetor) and all others.

Injection engine

Other causes of black candles

malfunction of the ignition coil or incorrect setting of the advance angle;
high wear of valves, piston rings or condenser;
The products themselves have faults.

Rich mixture

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The reasons for abnormal over-enrichment of the mixture can be very diverse:

overflow nozzle or misregulated carburetor metering system;

air filter clogged with dust;

incorrect operation of sensors or oxygen feedback of the engine management system;

abnormal pressure in the fuel rail;

the consequences of illiterate tuning when trying to get an increase in power by simply enriching the mixture.

Poor self-cleaning

Clogged air filter

It may also cause darkening of the spark plugs.
It needs to be checked and, if anything, replaced with a new one. Ignition system: the ignition angle is incorrectly set, the insulation of the wires is damaged, the integrity of the cover and the thrombler slider is damaged, then the ignition coil is not working properly and in the end it’s all about the spark plugs themselves.

All of the above reasons can lead to inconsistent sparking, in which case not only gasoline combustion occurs, but also coal-black soot appears on the spark plugs.

Heat number discrepancy (CN)

Burnt out valves (ICE)

Very often, valves burn out or the gaps are not adjusted correctly.
This also results in carbon deposits on the spark plugs.

A black spark plug corresponds to a reduced compression ratio in the cylinder.

What consequences may arise with late ignition and full operation on a rich hot-air mixture: inconsistent ignition, difficulties in starting the internal combustion engine, unstable operation.

Misfires

They do not always depend on the candle. This could be a half-dead ignition coil, high-voltage wires with leaks, weak pulse parameters in terms of voltage and rising edge, and so on, there are a lot of reasons. Ideally diagnosed with an oscilloscope, although there are simpler methods. In any case, the spark plug will cool down, which will reduce the situation to the one described above.

In fact, the ignition system alone cannot be blamed for misfires. As popular wisdom says, there is either nothing to burn, or nothing to set on fire. And you can also add mechanical problems. Diagnostics to help. And the control system computer can provide data on the number of cylinder misfires; it constantly and diligently counts them, typing giant multi-digit numbers in the event of a malfunction.

Loss of compression

For high-quality combustion of the mixture, it must first be highly compressed. If the compression is, for example, 12 , then this means that the pressure at the moment of ignition 12 times greater than atmospheric pressure. When this parameter decreases from the norm, not only do combustion conditions worsen, but also some of the working gases in the most unpredictable composition leave the combustion chamber due to insufficient mixing of gasoline with air. Among other troubles, this will lead to the appearance of black spark plugs, which is caused by mechanical problems. Moreover, with an uneven geometric location. A burnt-out valve may show a characteristic torch, or coked spark plugs and a scored cylinder mirror will leave their mark in the form of one-sided coloring of the insulator.

Unsuitable gasoline

This problem is similar to the previous one. Fuel with different octane numbers, in addition to differences in resistance to detonation, has different burning rates. And if the engine cannot adapt to large deviations, then the effect will be the same, accompanied by a violation of the thermal regime of the spark plugs.

But in addition to detonation properties, the fuel may simply be of poor quality. All kinds of counterfeit gasolines of criminal distillation contain heavy fractions of oil and other impurities that are unsuitable for use in a modern engine. The soot from this entire set will be deposited on the candles, coloring them in an already known color and quickly rendering them inoperative. And attempts by manufacturers to give the counterfeit detonation resistance with the cheapest additives in large quantities will additionally provide the insulators with a red tint. It is also conductive, so such a candle will no longer work normally.

Late ignition

The combustion rate of the mixture is limited to a very specific value, depending on its qualitative composition and degree of compression. If combustion is initiated too late, and not a few degrees before top dead center, as expected, then the charge does not have time to burn out completely, going through the exhaust valve to heat the exhaust system and leaving black soot on the spark plugs. Early ignition is even more harmful to the engine, but it does not color the spark plugs. Rather, it simply destroys by detonation.

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Spark plug defects

Both breakdowns and fatigue of materials that occur during operation, as well as initial manufacturing defects, make the spark plug unsuitable for stable operation. All this leads to the already discussed case of misfire with all the consequences. The most common is to increase the gap between the electrodes. The metal gradually burns out, the spark gap grows and goes beyond reasonable limits. Eventually, under certain conditions, the discharge voltage begins to be insufficient for breakdown, and the charge leaves along an easier path, through the outside air or flowing down the insulator. Which, in turn, is covered with conductive deposits on a worn spark plug.

A similar case will be when the spark plug was initially selected in violation of factory recommendations. Most often this happens in the pursuit of car enthusiasts for multiple electrodes. This is supposed to increase the power and reliability of the spark discharge. Yes, some companies use such spark plugs from the factory. But there are no more than two side electrodes, and the use of this feature by a well-known company does not change the controversial issue at all. Manufacturers are not always guided by technical expediency. In practice, multi-electrode spark plugs do not bring anything good. Developed side electrodes shield the discharge from the fuel mixture, reduce the reliability of sparking and cause the formation of soot.

In addition to stationary processes leading to contamination of spark plugs with black deposits, there are cases of one-time carbon coating. For example, separating large pieces of carbon deposits from the piston bottom, starting the engine at extremely low temperatures, or throwing oil into the combustion chamber once. Over time, the candle will clear. But the question arises: is it necessary to clean the spark plugs covered with soot as the cause of its formation is eliminated, or does it make sense to replace them as a set with new ones? If the spark plugs are the most common ones, based on nickel alloys, then their reliable service life does not exceed tens of thousands of kilometers. This set needs to be changed. But if it is expensive platinum and iridium, then such devices are characterized by increased durability. After careful cleaning, preferably using a specialized sandblasting machine, such a spark plug will be no worse than a new one, and the savings will amount to a decent amount.

How to remove black carbon deposits from ignition elements

Stable and correct operation of a vehicle engine largely depends on the good functioning of the ignition elements. Periodic inspection will protect your car from serious malfunctions and expensive repairs. It is imperative to carry out a visual inspection of the engine if the engine is not functioning properly or if it is difficult to start.

Car enthusiasts need to remember that the elements undergo self-cleaning at high temperatures when the engine operates at high speeds.

Carbon deposits can be removed from the ignition elements mechanically or using cleaning agents.

Mechanical cleaning method

The simplest cleaning method is to remove carbon deposits using sandpaper or a metal brush. Although this method is attractive in its simplicity, professionals do not recommend using it to clean black candles in order to avoid removing the thinnest deposit of precious metals applied to the electrode of the product. During mechanical cleaning of the SZ, it may be damaged. In addition, scratches form on the insulators, which leads to a much greater accumulation of soot.

Mechanical cleaning method

Chemical method

It is no coincidence that car owners prefer to clean elements using a chemical method. Black carbon deposits from candles can be easily cleaned using conventional cleaning products designed for cleaning tiles and plumbing fixtures. Cleaning requires a small container, a rag and a toothbrush. Having prepared everything you need, follow these simple steps:

Place the elements in a basin (bucket) and fill them completely with the prepared solution.
Leave in the solution for 30 minutes (more is possible).
Clean the element with a toothbrush.
Rinse in running water and wipe dry with a cloth.

Before putting the elements in place, you need to dry them well. To do this, place them in the oven for 20 minutes or blow them with a hairdryer at minimum power.

Self-diagnosis of ignition elements

Both an experienced motorist and a novice driver can visually check the elements for damage A symptom of spark plug diagnostics is instability in engine operation. The most optimal method for checking the operating condition of the SZ at home is to check the spark. To do this, they need to be removed and cleaned of carbon deposits. Then put it on the wiring element and bring it closer to the cylindrical block. If you see a red spark or it does not appear at all, then the element needs to be replaced.