Why does black smoke appear when accelerating hard?

What is the reason?

The main thing that black smoke from the exhaust pipe indicates is a supersaturated fuel-air mixture. A lot of fuel enters the cylinders, it does not have time to burn properly, and the exhaust turns black. It goes without saying that it is more harmful and toxic than normal exhaust, and even the catalyst cannot cope with excess fuel in the exhaust gases.

The main reason for this is problems with the fuel supply system . This problem can occur in absolutely all internal combustion engines, both gasoline and diesel.

The second reason lies in the ignition system. The fuel is not ignited in the chamber, and a raw mixture exits into the muffler. The engine, in this case, will “trouble” very strongly (Troubles the engine - the engine does not work correctly, since the fuel does not completely burn in any cylinder. For example, three cylinders work as they should, but the fourth is not quite right. Or ignition does not occur, or the fuel burns poorly).

Carburetor ignition.

As for carburetor engines, everything is quite simple. If the exhaust is black, most likely the carburetor itself is unstable, namely the overflow in the float chamber. There may be several reasons:

The needle valve is faulty. The “needle” can leak excess fuel and even get stuck.
The jets could become clogged. The main reason for this is low-quality fuel.

To fix the problem, you need to disassemble and clean the carburetor. If this does not help, you will have to change the “needle” and jets, and then correctly set the gasoline level in the chamber.

Injection engine.

On the one hand, everything is simpler here, since there are no “needles” or combustion chambers. On the other hand, it is more complicated, since there is a completely different fuel supply system. Here, the fuel-air mixture is supplied electronically, and injection is carried out using “injectors”. Hence the name of the engine.

The main causes of black smoke from the exhaust pipe on an injection engine are as follows:

The main problem here may be the injector itself. Simply, it becomes clogged and does not supply fuel properly. Pressure builds up and then a strong injection occurs, often with excess fuel. Because of this, the engine is unstable, it begins to “float”: sometimes low speeds, sometimes high. To fix this, the injectors need to be cleaned. There are several ways to do this. You can remove the fuel rail, or you can use special products that are added to gasoline. Which is better is up to you, of course, but this will help get rid of black exhaust. It is better to carry out the procedure once every 70,000 kilometers.
Since the injection engine system is fully automated, it monitors all the different operating cycles using sensors. From this it follows that the sensor is faulty. If so, it will either supply too much fuel or prevent the engine from starting at all. It is unlikely that you can identify this breakdown yourself; you will have to go to a service station for diagnostics.
The third reason is the fuel pump. In cars with injection engines, it is usually located in the gas tank, and there are times when it begins to supply increased pressure. This leads to overflow in the injection chambers. The solution to the problem is to replace the pump.

Diesel engines.

If you look, for a diesel engine, black exhaust is normal. Again, this is a different system, the fuel is ignited by pressure, it runs on diesel fuel, and it produces a slightly blackish exhaust even in normal condition. But today they are also trying to combat this phenomenon, because diesel engine exhaust is toxic and contains a lot of lead. Therefore, in order to comply with EURO5 standards, particulate filters began to be installed on all diesel engines. It purifies exhaust gases and prevents harmful substances from entering the air.

And what problems can diesel engines have?

A banal failure of the particulate filter . If so, it needs to be replaced. But the intensity of the smoke will not be as high.
The high pressure pump has failed and there is an overflow of fuel. Again, everything is solved by replacing it.
Incorrect ignition timing. Here you need to adjust everything correctly.

Fuel system malfunctions

Over-enrichment of the fuel mixture occurs as a result of malfunctions of the carburetor, injector or high-pressure fuel pump in a diesel engine. In this case, blue smoke is accompanied by difficult starting, unstable idling, loss of power and, as a result, increased fuel consumption. The smoke coming out of the exhaust pipe is dark gray or black, especially visible against a light background. In some cases, the black smoke coming out of the exhaust pipe may even contain visible soot particles.

In cars with a carburetor engine, this malfunction often occurs due to fuel overflow in the float chamber caused by coking of the air jets, valve malfunction or incorrect adjustment of the float.

For injection engines, this occurs due to malfunctions of the sensors that control the air content in the mixture or leaky injectors. Fuel leakage through the injectors can lead to water hammer when starting the engine. If a large amount of fuel enters, it will not allow the piston to go past top dead center. This happens extremely rarely, but the consequences can be very sad, including breakdown of the crank mechanism of the engine. Also, fuel entering the oil leads to its dilution and, as a result, increased wear of the rubbing surfaces in the engine.

In a diesel engine, the main reasons for the over-enrichment of the mixture, and the resulting bluish smoke, arise as a result of a malfunction of the fuel injection pump, an incorrect injection timing angle and, as with injection nozzles, leakage. Another reason why soot occurs in diesel engines is clogged particulate filters. Electronic systems warn drivers about the need to replace filter elements, but some craftsmen throw away the filter and block the electronics using all sorts of tricks. Therefore, in such cars, blue smoke may appear as a common phenomenon, making it difficult to diagnose the engine at the initial level.

The consequences of malfunctions in fuel equipment can be serious problems. As already mentioned, this is wear of rubbing surfaces as a result of oil dilution. Also, as a result of excess fuel entering the cylinders, the oil film is washed off from the surfaces of the cylinder walls, which causes premature wear of the cylinder-piston group in the rubbing pair. When fuel burns incompletely, soot is deposited on the cylinder walls and pistons, leading to the formation of scoring on the surfaces. As a result, all this leads to a decrease in engine life and large monetary costs for car repairs.

Cause of black smoke from exhaust

It is interesting that, regardless of what type of engine such a misfortune happens to, the common cause in most cases is the same, and it is that a too rich air-fuel mixture is supplied to the combustion chamber. But why, you need to consider a specific type of engine, since a gasoline engine produces much less black smoke than a diesel engine.

As for the ignition system, the two most common options are problems with the spark plugs or with the coil/coils. If the spark plugs do not produce a spark with the required power, then the air-fuel mixture does not burn completely. The result of this is, among other things, black carbon deposits on the electrodes. And sometimes the spark plugs are completely filled with fuel, making it difficult to start the engine. In a diesel engine, there are glow plugs, and if they are not heated correctly, they cause increased smoke, because the fuel is then not burned.

In a gasoline engine, the result of incomplete combustion of fuel can be the coil. If it is damaged, misfire may occur in individual cylinders.

In the fuel delivery system, problems in this context may be related to the fuel pump and/or fuel injectors. If they partially fail, fuel may be overfilled beyond the norm, resulting in the formation of an enriched air-fuel mixture.

Separately, it is worth focusing on low-quality fuel. Unfortunately, in our realities, many motorists are faced with the fact that gas stations sell low-quality fuel. This applies to all types of fuel - gasoline, diesel fuel, liquefied gas. If there is a significant presence of non-combustible impurities in their composition, the normal operation of the engine will be disrupted, which can lead, among other things, to the appearance of black smoke from the exhaust.

What does car exhaust say?

The exhaust can be of different colors, sometimes if you notice smoke that is not typical for your car, you should think about it and check the condition of the power unit.

White exhaust may appear after the vehicle has been parked for a long time. This is due to condensation that accumulates in the exhaust system and begins to evaporate when the engine starts. The outside air temperature also affects the formation of white smoke. The colder it is, the more and longer the smoke comes out.

Therefore, in frosty weather, smoke can constantly come out. It's worse if white smoke comes out in warm weather. This may indicate that working fluid from the cooling system has entered the cylinder.

In this case, it is necessary to disassemble the engine, remove the cylinder head, change the cylinder head gasket, repair cracks, check the tightness of the head, and the like.

To check and confirm that liquid has entered the cylinders, you need to perform a number of actions:

Start the engine, open the cap of the cooling system expansion tank and check for fluid bubbling. If bubbling is present, it means that gases are breaking into the cooling system. When the engine is turned off, the coolant level decreases, as part of it goes into the engine cylinders.
You should pay attention to the color and condition of the liquid in the cooling system, the smell of burning, the presence of greasy stains on the surface, changes in color, density, etc. This may indicate microcracks and defects in the motor.
It is necessary to check the oil level; there are often cases when it rises as a result of liquid from the cooling system entering it. As a result, the engine oil thins out and becomes cloudy, and an emulsion appears in it.

It is better not to use the engine until the problem is resolved, so as not to aggravate the situation. In the worst case, as a result of a large accumulation of fluid in the space above the piston, a hydraulic shock can occur, which will damage the power unit and lead to expensive repairs.

A gasoline engine usually produces black exhaust from the muffler when starting up; this occurs due to problems in the power system. In this case, the working mixture of fuel and air is greatly enriched, and more fuel enters the combustion chamber than necessary. The signs of this situation are as follows:

Starting the engine is difficult;
The spark plugs are filled with fuel;
When starting, the power unit malfunctions and is not stable;
Loud noise in the muffler operation, popping;
High fuel consumption;
The engine does not produce its former power;
The on-board computer displays an error;
Smell of gasoline when the unit is running

When the engine is running, the color may vary from gray to jet black. This is due to the fact that during operation a large amount of soot accumulates and over time it is released into the atmosphere.

There are many reasons that lead to fuel supply failure. You need to start looking for problems with the fuel supply systems. On carburetor engines, it is necessary to check the metering device, fuel and air jets, and the float chamber.

It is necessary to check the ignition system; it happens that when some element fails, such as the ignition coil, high-voltage wires, spark plugs, the engine as a whole fails.

Black smoke from carburetor exhaust pipe

If an engine with a carburetor has black smoke coming out of the exhaust pipe, the first thing you need to do is check the carburetor itself. Most often, the so-called “overfill” occurs, that is, the amount of incoming gasoline exceeds the norm. In turn, this can happen for two reasons.

The first is that the needle valve (colloquially called a “needle”) is faulty. It simply sticks and excess fuel passes through it. The second reason is clogged jets. They are small diameter nozzles. Often, when using low-quality domestic fuel (or simply over time), they become clogged, causing an over-enriched mixture to be created in the carburetor.

Often, to solve the problem, it is enough to clean it with a carb cleaner. If simple cleaning does not help, you need to buy a carburetor repair kit, which usually includes a new valve and jets. Replace them accordingly. At the end, you need to correctly configure the carburetor and set the gasoline level in the chamber.

What to do about this phenomenon

If you suddenly encounter black smoke and you are wary of continuing to use your machine, there are a few diagnostic steps you need to take to determine the cause:

add high quality fuel and drive a short distance to assess the quality of the exhaust gases;
make sure that the fuel filter does not contain dark particles or small debris (this can color the exhaust gases);
Replace the air filter to prevent contaminants from entering the engine;
if you have the required knowledge and qualifications, test the operation of the injector, visually check the injectors themselves. Only if you are sure that you will not make things worse;
if you have a diesel engine, you can safely return the injectors for cleaning, in 90% of cases this will eliminate the appearance of black smoke;
you can also measure the compression in the cylinders to make sure that every part of the engine is working smoothly;
adjust the valve and ignition (important for older carburetor cars).

These steps can help diagnose and resolve the problem yourself.

Smokes black from the exhaust injector

Answering the question why black smoke comes from the exhaust pipe of an injection engine, three main reasons can be identified.

Problems with injectors

On an injection engine, as on a carburetor engine, the injectors become clogged over time, especially when using low-quality fuel. In this case, first a situation occurs when, due to clogged injectors, there is not enough fuel, and then a certain moment comes when the tightness of the needle valve is broken, they begin to let an excessive amount of fuel into the combustion chamber. Naturally, under such conditions the engine will operate unstably, “triple”, the engine speed will “float”, especially at idle.

In this case, it is recommended to clean the injector nozzles. It is recommended to carry out this procedure using special cleaning products every 60...70 thousand kilometers, regardless of what kind of gasoline you use.

Faulty sensors

The operation of the injection engine is based on commands from the electronic control unit (ECU), which, in turn, receives information from sensors located in the engine. Accordingly, if incorrect information is received, the control unit may give a command to form a too rich mixture, which will lead to the appearance of black smoke from the exhaust pipe. What kind of fuel is used, gas, gasoline or diesel fuel, does not matter in this case. In this case, black smoke will only be an external sign of a malfunction. Also, the car will lose its dynamic characteristics, the engine will “trouble”, “sneeze”, and the idle speed will fluctuate.

Oil getting into the cylinders

The next main reason for the appearance of bluish smoke from the exhaust pipe is oil getting into the combustion chamber of the engine. As a result of this malfunction, blue or even black smoke appears from the vehicle's exhaust pipe. It all depends on the amount of oil that gets into the cylinder. The main reasons for oil entering the combustion chamber are:

wear of the piston group;
malfunction of oil scraper rings;
wear of oil seals.

Wear of the pistons leads to the fact that oil from the engine crankcase enters the combustion chamber through an increased gap. There, part of the oil burns, forming bluish smoke, and part is deposited as soot and tar deposits on the cylinder walls, increasing engine wear.

Seized piston rings or their breakage have the same consequences as wear of the piston group. In this case, less expensive work to replace the piston rings leads to a costly engine overhaul. Over time, the light bluish smoke turns into blue and then black, indicating the need for serious repairs.

A clear example of how a small repair can lead to large costs is the wear or loss of elasticity of engine oil seals. With this malfunction, a large amount of oil remains on the rods and flows to the valve plates. On the intake valves, it is deposited in the form of carbon deposits, which subsequently leads to a loose fit and possible breakthrough of hot gases into the intake manifold. Exhaust valves have even worse consequences. In this case, there may be burnout of the valves due to a decrease in heat dissipation capacity, as well as wear of the guides, bending of the valve due to incomplete closure and breakage of the cylinder head.

It is better to entrust it to a good specialist to understand the reasons why blue smoke is coming out, but initially you can determine the cause of the malfunction yourself. If there is a malfunction in the power system, the bluish smoke that comes out is deposited on the walls of the exhaust pipe as soot or dry soot deposits. In case of malfunctions associated with the lubrication system, the deposits, as a rule, have an oily form, and in extreme cases, the oil, as they say, “flies out of the pipe.” In any case, if any unusual smoke appears from the exhaust pipe, you should urgently understand the reasons and take immediate measures to eliminate the malfunction.

Black smoke from diesel exhaust

Please note that the exhaust of even a working diesel engine has a black-blue tint, unlike gasoline or liquefied gas. Therefore, it is necessary to distinguish between the normal amount of exhaust gases and their excessive amount, especially taking into account the fact that the gases have a characteristic black color.

Any diesel engine is characterized by 4 main reasons why black smoke comes out of the exhaust pipe:

lack of air (both clogged air filter and damage to the intake pipe);
weak compression;
leaking injectors (especially noticeable when you press the gas sharply or when driving with a load);
the injection timing angle is broken (an early angle leads to increased soot formation).

More about these and other reasons below.

Particulate filter

Black smoke from the exhaust of a diesel engine will depend on what environmental standards the car's engine meets. Modern environmental standards, in particular Euro-5, require the installation of a particulate filter, the task of which is to clean exhaust gases from harmful substances. Accordingly, if it fails, black smoke will pour out.

If the particulate filter is partially clogged, black smoke comes out of the exhaust pipe when over-gasping or simply when operating in normal mode. There are two ways out of this situation - replacing the particulate filter or cleaning it.

High pressure pump

In diesel engines, a high-pressure pump (HP pump) is responsible for supplying and dosing fuel. Accordingly, when its work intensity increases, it produces a larger amount of diesel fuel than necessary, which is why an overflow occurs, which also leads to rich black exhaust gases.

On old-type (classic) diesel engines, it is enough to check the operation of the pump - its performance, the output pressure. In modern diesel engines, in particular those equipped with a Common Rail system, it also makes sense to check the operation of the sensors from which information is sent to the electronic engine control unit. Receiving incorrect information from them can also cause black smoke from the exhaust pipe when you sharply press the gas pedal or simply during normal engine operation.

Ignition timing

The point is that in conventional (classical) diesel engine systems the ignition angle may be incorrectly set, including due to chain stretching. This can cause black smoke to appear from the exhaust when it is cold, when it is hot, and in other conditions.

Please note that in modern common rail diesel systems there is no such problem, since the advance angle is set automatically by the engine control unit. If in such a system the angle is lost, it is necessary to check the functionality of the electronic control unit itself, as well as the operation of the sensors that affect the correct operation of the engine.

Turbocharged engines

Engines equipped with turbines have their own nuances. In particular, the turbine may be the cause of the appearance of black smoke from the exhaust pipe. Under normal operating conditions, the pressure should be 0.8...1 atmosphere above standard atmospheric pressure. If the measured pressure is higher or lower than specified, both cases may result in black smoke in the exhaust gases.

Intake tract

A fairly common cause of black smoke from the exhaust pipe is reduced flow of the intake tract. Most often, the critical element in this case is the air filter. It may be blocked for trivial reasons - it was changed a long time ago, not in accordance with the current regulations.

Accordingly, less air passes through it than is necessary for normal operation, while fuel remains at the same level. This means that it is necessary to check the condition of the air filter and, if it is clogged, replace it with a new one.

EGR system

A fairly common reason why black smoke comes out of the exhaust pipe is a faulty exhaust gas recirculation system - EGR (Exhaust Gas Recirculation). The fact is that USR systems are mainly equipped with engines of European cars with a temperate climate. But in severe frosts, the diesel engine does not warm up so quickly, which is why the dampers and servos of the EGR components simply become clogged with soot. After all, the enriched mixture is served longer than usual.

Exhaust pipe smoke and its causes

The durability of a car depends on quality maintenance and proper operation. But this does not provide a 100% guarantee that there will be no problems in the vehicle’s operating system. One of these problems may be soot from the exhaust pipe. The reasons for the appearance of black smoke from the muffler in gasoline and diesel engines are different. Let's look at them in more detail.

Petrol engine option: black smoke

Black smoke coming from the tailpipe of a diesel engine indicates that too much fuel is being burned. Then the cause can be eliminated in several ways.

The carburetor needs adjustment. This process is very difficult and it is better not to do it yourself, but to seek the help of a specialist.
It is necessary to see how tight the injectors are. They may not be fully closed. In this case, more fuel is supplied than can be burned. The consequence of this is the formation of soot, which causes the appearance of black smoke.
If there is a malfunction on the side of the mass air flow sensor, its readings regarding incoming oxygen are incorrect. The ratio of oxygen and gasoline in the fuel mixture is disrupted. This situation causes black smoke to come out of the exhaust pipe.

Diesel: black smoke

Causes of black smoke in a diesel engine:

This is essentially the same as with a gasoline engine, but there are some subtleties:
There may be a situation in which there is excess pressure in the ramp. The pump is subject to calibration, that is, it just needs to be configured correctly. If this is not done, black smoke will appear in the exhaust;
Otherwise, the reasons are the same as in the gasoline version of the power unit.

Gasoline engine: blue smoke

If blue smoke appears from the exhaust pipe, then, unfortunately, there is no way to do without repairs. If a car smokes blue smoke, then we can say with confidence that there is oil in the cylinders. How it gets there is a completely different question, the important thing is that it is already there. As a rule, the cause of smoke from the exhaust pipe may lie in wear and tear of parts.

Watch a video about what to do if you see blue smoke coming from your exhaust pipe.

Blue smoke is formed because gasoline burns together with oil. We need to thoroughly analyze everything and establish the reason why it got there.

Oil seals may wear out. This will certainly lead to the appearance of bluish smoke. This is usually observed when the oil is changed, especially if it was done at the wrong time. Old oil has slightly higher viscosity. In the old mass, naturally, there is an accumulation of debris and dirt. They can act as an oil seal. As long as the engine is running on old oil, things are still relatively tolerable. Filling in new oil simply washes everything away from dirt.
Oil scraper rings may wear out. And at the same time, blue smoke may also appear. Their job is to collect oil from the cylinder walls as the piston moves down. If the ring wears out, oil may remain in the cylinder. And while the piston goes up, oil is collected by the compression rings. This is not difficult to recognize. You just need to check the compression.

If there is bluish smoke, it is imperative to monitor the oil level, as its increased consumption will inevitably occur. If such a malfunction manifests itself and is noticed, then the driver should reduce his ardor and not drive at high speeds.

The most ideal condition for checking the exhaust color is when the car starts uphill. You also need to see whether the pipe is dry or not. The oil itself in the cylinder is not subject to combustion. It gets into the exhaust and, naturally, will remain on the walls of the pipe, and this will not be difficult to notice.

Read about the car exhaust system. And also about caring for the exhaust system.

White smoke

When white smoke comes from the muffler, it is important to pay attention to the weather. It might just be steam. After all, the exhaust temperature is quite significant. If the pipe is dry and there is no condensation on it, you need to look at the color of the spark plug. Most likely, they will also have white residue on them. Then you need to think that the fuel mixture is not rich enough, so white smoke may appear from the muffler.

The reasons may be:

the fuel pump is faulty. And this may be due to insufficient pressure in the ramp and insufficient fuel in the fuel mixture;
The injectors may become clogged. In this case, naturally, less fuel is supplied;
It is common for a fuel filter to become clogged. And again there is a lack of fuel.

Consequences of increased soot formation

The first negative point that you will notice is a decrease in engine power with increased fuel consumption, but if you are interested in the question of what are the consequences of black smoke from the exhaust pipe, and is it even possible to drive a car with such a symptom, you can note 5 main warnings:

environmental damage due to increased CO2 in exhaust gases;
load on catalyst (particulate filter);
burnout of pistons and valves (the entire CPG is under attack as excess fuel gets into the oil, scoring occurs);
malfunction of valves (hanging due to carbon formation);
risk of water hammer as fuel can literally pour into the cylinder.

Have you ever experienced black smoke coming from your exhaust pipe? What do you think about it? Share your opinion in the comments.

Many car enthusiasts noticed that their car began to emit black smoke from the exhaust pipe. But not everyone understands the reasons for this effect, as well as methods for eliminating it.

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Lada Kalina 2. The engine smokes black smoke

Smoke comes out in the form of a thick black exhaust from the muffler, and it comes out especially strongly when you press the gas pedal. Moreover, the car does not operate stably, the engine often “troubles” and starts poorly in the morning (especially in winter). Fuel consumption increases. Black smoke may be the result of a deliberate enrichment of the combustible mixture by the control unit to ensure stable operation of a cold engine immediately after starting at low ambient temperatures. This phenomenon occurs briefly and disappears long before the engine warms up to operating temperatures.

Main reasons

Black smoke indicates that the fuel-air mixture is too rich (over-rich). A lot of fuel enters the cylinders, which does not have time to burn effectively, so the exhaust is repainted black. It is much more toxic and harmful than normal exhaust, because even the catalyst cannot promote the combustion of excess fuel in the exhaust.

The main reason for this is a malfunction of the fuel supply system, which occurs in all types of internal combustion engines (gasoline, diesel).

The second reason may be a malfunction in the ignition system; the fuel is not ignited in the chamber and therefore the raw mixture goes directly into the muffler, and the engine will mercilessly “triple”.

With carburetor ignition

With a carburetor, everything is quite simple - if the exhaust is painted gray and black, there is instability in operation; first of all, you need to look at the carburetor itself. Most likely, there is an overflow in the float chamber.

This happens for two reasons:

1) The “needle” (needle valve) is faulty; it can stick or, on the contrary, leak excess fuel. 2) The jets are clogged and coked (from our fuel). Small "nozzles" with precise size.

You need to disassemble the carburetor and clean it; if that doesn’t help, then you need to buy a repair kit and replace the “needle” and jets and correctly set the gasoline level in the chamber.

Injection option

Here everything is a little more complicated on the one hand, and simpler on the other. The injector does not have chambers with needle float, etc., it is a completely different system that supplies the fuel-air mixture using electronics. Injection into the cylinders occurs using special devices - “injectors”, hence the name.

The main causes of black exhaust:

1) Often the cause is the injector itself; it simply becomes clogged and cannot supply fuel normally. There is an accumulation of pressure, and then a “strong” injection, often with excess. The engine operation will not be stable, sometimes low speed, sometimes high - in simple words it will “float”. In such a situation, you need to clean the injectors, there are many different methods, from removing the fuel rail to special agents that are added to gasoline - it’s up to you, but after such manipulation you can often get rid of black smoke from the exhaust pipe. Performance is restored. Cleaning should be done at least once every 60 - 70,000 kilometers. 2) Since the system is automated, it monitors various cycles using sensors. So, if the sensor is faulty, it will either prevent the car from starting at all, or it will supply too much fuel. Here you are unlikely to be able to diagnose the breakdown yourself; you need to go to a service station.

3) Fuel pump. Typically, injectors have it in the tank; there have been cases when it supplies increased pressure. Which also led to overflow in the injection chambers. Needs to be replaced again

Diesel engine smokes

Black smoke emerging from the exhaust pipe of a car indicates that the air-fuel mixture is over-rich. Running the engine on such a mixture increases wear and scuffing of parts and assemblies of the cylinder-piston group. This is explained by the fact that excess diesel fuel washes oil from the cylinder walls, thereby impairing lubrication. In addition, diesel fuel also gets into the oil, diluting it and worsening the lubrication conditions in other engine parts. Often the dilution rate becomes so high that the level of the fuel-oil mixture in the crankcase rises and a characteristic odor appears.

This indicates malfunctions in the power supply, ignition and injection control systems.

The main causes of black smoke

Black smoke when starting the engine is not a good sign. Most likely, the vehicle has developed quite large problems within the power unit or related systems. As practice shows, the formation of such an effect on engines is mostly associated with a malfunction of the fuel system.

Thus, the release of one of the elements leads to the fact that the engine begins to flood and the formation of the air-fuel mixture is disrupted.

So, why is there black smoke coming from the engine exhaust pipe? This issue requires deeper consideration. For each engine top, this will be a separate reason, but it is inextricably linked with the formation of the air-fuel mixture. Let's get started.

Carburetor engine

For a carburetor gasoline engine, everything is quite simple and clear. Many owners of this type of vehicle have encountered the problem that the engine simply floods, after which it begins to “chop” and stall, and black smoke comes out of the exhaust system.

So, let's look at the main causes and methods of elimination:

Carburetor needle. This element tends to stick, especially when low-quality fuel is filled. As a result, overflow begins and the fuel does not burn completely.
Ignition. Damaged spark plugs or incorrect ignition timing are also a cause because the fuel does not burn completely, causing black smoke to form.
Many auto repairmen say that another reason for the formation of black smoke is wear of the piston rings and wear of the valves. In this case, it is best to contact a car service to troubleshoot the problem.

Injection engine

Things are a little worse with the injector. The appearance of black exhaust indicates that first of all, it is worth checking the injector and injectors. It is in clogging or too much fuel pressure that the problem may lie. To diagnose these elements, there are special test stands at specialized car services.

So, many motorists try to do the cleaning themselves, but this is not always successful.

If the engine starts and black exhaust comes out of the muffler, then the gasoline engine could have suffered another malfunction - the fuel pump has broken down. In this case, the amount of fuel supplied may be disrupted. So, the engine simply floods and it is not the air-fuel mixture that enters the combustion chambers, but the fuel flows in a stream.

Another very important reason for the formation of smoke in the exhaust can be a clogged air filter. Therefore, it is recommended to change this element regularly and in accordance with technical maintenance cards.

Like the air filter element, a clogged throttle can cause problems in the formation of the air-fuel mixture. Cleaning this element is quite easy with your own hands using carburetor cleaning products.

For the injector, as for the carburetor, a malfunction in the ignition system leads to an accumulation of fuel that does not burn out. Thus, when carrying out diagnostic operations, it is recommended to check this unit as well. Perhaps one of the spark plugs or a high-voltage wire has failed, which has caused this effect to occur.

Black exhaust from a gasoline engine muffler

While the engine is running, the color of the exhaust gases may vary; this is an unusual indicator of the condition of your unit. On corrected engines, when starting, white smoke comes out for a short period of time.

If the engine is faulty or in poor condition, it may produce white, dark, blue or bluish smoke.

If during engine operation there is constant white, dark, light blue or bluish smoke, this is a reason to check it.

Let's look at why dark smoke appears when starting the engine, what blue smoke indicates, and also why white smoke comes out of the engine.

What does a car ejection mean?

The emission may be of different colors, from time to time you notice smoke that is not typical for your car, it is worth thinking about and checking the condition of the power unit.

The emission may appear white after the vehicle has been parked for a long time. This is due to condensation that accumulates in the exhaust assembly and begins to evaporate when the engine starts. The outside ambient temperature also affects the formation of white smoke.

The colder it is, the more and longer the smoke comes out.

Therefore, in frosty weather, smoke can continue to flow. It’s worse if white smoke comes out in warm weather.

This may indicate that working fluid from the cooling system has entered the cylinder.

In this case, you need to disassemble the engine, remove the cylinder head, change the cylinder head gasket, repair cracks, check the tightness of the head, and the like.

To check and confirm that liquid has entered the cylinders, you must perform the following sequence of actions:

Start the engine, open the cap of the expansion tank of the cooling system and check for fluid bubbling. If bubbling is present, therefore, gases break into the cooling system. When the engine is turned off, the coolant level decreases because part of it goes into the engine cylinders.
You should pay attention to the condition and color of the cooling liquid, the smell of burning, the presence of greasy stains on the surface, changes in color, density, etc. This may indicate defects and microcracks in the motor.
It is necessary to check the oil level; there are often cases when it increases as a result of liquid from the cooling system entering it. As a result, the engine oil thins out and becomes cloudy, and an emulsion appears in it.

It is better not to use the engine until the problem is eliminated, so as not to aggravate the situation. In the worst case, as a result of a huge accumulation of liquid in the space above the piston, a hydraulic shock can occur, which will disable the power unit and lead to expensive repairs.

A gasoline engine produces a dark emission from the muffler, in most cases, upon startup; this appears due to troubles in the power supply system. In this case, the working mixture of air and fuel is greatly enriched, and more fuel enters the combustion chamber than necessary. The indicators for this situation are as follows:

Starting the engine is difficult;
The candles are filled with fuel;
When starting, the power unit malfunctions and is not stable;
Loud noise in the muffler operation, popping;
Enormous fuel consumption;
The motor does not produce the same power;
The on-board computer is inaccurate;
Smell of gasoline when the unit is running

When the engine is running, the color may vary, from gray to charcoal dark. This is due to the fact that during operation a lot of soot accumulates and over time it is released into the air.

There are quite a large number of circumstances that lead to disruption of the fuel supply. You need to start looking for problems with the fuel supply systems.

On carburetor engines, you need to check the metering device, fuel and air jets, and the float chamber.

It is necessary to check the ignition system; it is not uncommon that when a specific element fails, such as the ignition coil, high-voltage wires, spark plugs, the engine as a whole fails.

It is necessary to check the condition of the air filter; if it is dirty, the mixture entering the cylinder will contain a large amount of fuel.

On engines with injectors, the electronic engine control system fails from time to time. By transmitting incorrect data to the control unit, the controller increases the fuel supply.

Which in turn leads to an excess of the fuel mixture.

Also, the injectors in the engine can lose their tightness and pour fuel into the combustion chamber.

Filling candles with fuel not only causes an excess of fuel, but also many other troubles. For example, washing off the oil film from the cylinder walls, resulting in severe wear of the cylinders and piston group.

In addition, a lot of fuel enters the engine crankcase, which leads to oil dilution.

In any case, the motor lacks complete inspection, tuning and troubleshooting, otherwise the consequences will be very expensive.

Blue smoke when the engine is running indicates that engine oil is entering the combustion chamber.

Increased engine oil consumption will indicate that oil has entered the cylinder. Circumstances of oil penetration:

Severe wear of piston group parts;
Damage to the gas distribution mechanism

When parts wear out, the piston rings fail, and defects appear on the piston and cylinder walls.

If the gas distribution mechanism breaks down, there is no seal in the area of the valve stem and valve guide.

To repair, you will need to replace the valve seals. Measure the compression in the engine. If the decrease in compression is insignificant, then as work progresses, the bluish smoke disappears, since the gaps decrease when warmed up.

If the gaps are huge and the smoke does not end, repairs need to be made.

Let's sum it up

So, to eliminate smoke of dark, white, light blue colors, from time to time it is enough to replace the filter and clean the injectors. While in more important cases it is necessary to repair its mechanisms and engine.

We must not forget that if the engine suddenly starts smoking black, you need to replace the fuel, since low-quality fuel, with a high level of undesirable impurities and additive content, leads to changes in the color of the emission and difficulties in combustion of the mixture.

Do not forget that the timing belt must be installed according to the marks, the timing and timing valves must be clearly adjusted, and the thermal clearance of the valves must be set correctly. Spark plugs, during diagnostics, will help assess the condition of the engine.

The stability, durability and reliability of the power unit depends on everything, and many other indicators.

How to eliminate black smoke from the muffler

Diesel

For a diesel power unit, black smoke from the exhaust pipe is normal. So, the engine's particulate filter fails and requires replacement. Also, the cause may be a malfunction of the high pressure fuel pump, which does not control the fuel supply and simply floods the cylinders of the power unit.

There is a second danger for a diesel engine: if the cylinders are flooded and the fuel does not ignite, this can almost lead to water hammer. Also, the consequence can be considered that the degree of burnout of the valve mechanism and piston group increases, which undoubtedly leads to a major overhaul of the power unit.

It is worth noting that when black smoke repeatedly comes from the engine, then most likely the engine has carbon deposits on the walls and in the main components. To eliminate the problem, it is worth disassembling the engine and cleaning it.

The fact of occurrence of soot emissions

Black smoke appears from the muffler most often after pressing the accelerator pedal. The motor behaves unstable in such a situation and may stall. Often such cars start poorly, especially after a long period of parking or in the cold season. Increased fuel consumption is also possible.

Working with carburetor cars

In the case when the carburetor is responsible for preparing the fuel mixture, then with a high degree of probability it is the main culprit for the appearance of soot particles in gaseous emissions. Overflow occurs in the float chamber, and the reasons for this are hidden in the following factors:

damage to the needle valve, which leads to the supply of excess fuel for combustion;
blocking the passage channel for the needle, which minimizes the amount of gasoline;
clogging of the jets with foreign particles due to low-quality gasoline.

The solution to the problem is to clean and flush the carburetor. If this does not solve the problem, you will have to change the needle or jets. Next, we adjust the fuel level in the chamber.

It is important to know that cleaning the jets is strictly prohibited with steel tools, as this may damage the internal hole . We recommend using copper wire or soft non-metallic materials.

On older cars, one of the “diseases” is a clogged air filter. When the pores are clogged, it does not cope with its duties - to pass a sufficient volume of air for the air-fuel mixture. Thus, the mixture is obtained with the wrong proportion, over-enriched in fuel.

You need to know that the air filter must be changed at intervals of 10-12 thousand kilometers in order to maintain the passage of a sufficient volume of oxygen into the cylinders.

We recommend that the driver check the gap on the spark plugs. If the value set by the manufacturer is not observed between the electrodes, then the ignition coil is not able to produce sufficient sparking at the ends. This leads to failure of ignition and accelerated failure of the ignition system.

The engine will not operate properly if the spark plug gaps are unbalanced. Typically the interval should be between 0.9-1.1 mm. You need to measure it on all spark plugs using a feeler gauge.

Cleaning the injector

The design that uses an injector looks much simpler. There are no shut-off needles or combustion chambers. However, cleaning such a system can be more problematic, because a completely different fuel supply system is used.

All mixture formation processes in such a design are handled by electronics. Direct injection is carried out by an injector. This is often the main problem.

The main passage becomes clogged, which stimulates an increase in inlet pressure. In this way, a critical mass is accumulated, breaking through the passage. As a result, an excess amount of fuel enters the system, and the engine begins to operate unstably - “float”, producing uncontrollably low and then high speeds.

Correction requires mandatory cleaning of the canals, which you can do yourself. Experienced craftsmen know several ways to restore functionality. In some cases, the rail will need to be dismantled to free the channels, but this is a rather labor-intensive process. Most drivers use special fuel additives to remove contaminants.

It is worth considering that the rack must be cleaned at least every 60–70 thousand kilometers.

Motorists know that the injector operates automatically. Starting and fuel supply are dependent on the operation of sensors that monitor the current operating cycles. If failures occur, the culprit may be faulty sensors that send fuel to the engine in the wrong dosage (either too much or too little). It is unlikely that you will be able to identify such a breakdown yourself at home, so it is necessary to carry out diagnostics at service stations.

Another culprit for black smoke coming from the tailpipe in gasoline cars can be the fuel pump. For injection systems, the fuel pump is traditionally located in the gas tank. In the event of a possible breakdown, the unit is capable of sending fuel with excess pressure into the system, which provokes unwanted excess pressure and is realized as an overflow in the injection chambers. It is not worth repairing the VT, so you will have to replace it with a new one.

The cause of smoke with soot in some cases for both carburetor and injection cars is hidden in a clogged exhaust system . Under such contaminated conditions, the engine begins to perform its functions under additional load, which causes an increase in oil and fuel consumption.

The muffler becomes clogged, producing smoke clouds due to the destruction of the filter mesh. It crumbles and turns into small particles that clog the passages. At the same time, extraneous sounds are heard from the engine, and its temperature, even after short-term operation, increases significantly. The puffs coming out of the pipe have the aroma of burnt metal, so it is impossible to delay diagnostics and repairs in such conditions.

It is important to adjust valve clearances in a timely manner. Otherwise, incorrect configuration of this unit can significantly reduce the efficiency of the motor. The service life of the power plant is also significantly reduced.

A reduced level of clearances contributes to burnout of seats and valves. The carbon deposits formed first enter the cylinders, and then are sent to the muffler and into the atmosphere.

Black smoke from the exhaust pipe of the gasoline injector. Black smoke from gasoline exhaust pipe