The exhaust nozzle is black, what's going on?

turnover time :17-01-2019

I believe that many car-loving friends have had such ex […]

I believe that many car-loving friends have had such experiences. How did the serious exhaust pipe turn white? What should I do if the exhaust pipe becomes white? Is there anything wrong with the car? Recently, many riders have also asked this question, so today I will summarize and say:

First, strictly speaking, the exhaust pipe was black and was never a vehicle failure. The black particles are carbon deposits, which are formed by the waxes and gums in the fuel that have solidified for many years.

Summary of the reasons for the blackness of the exhaust pipe:

1. What about oil products?

2. Burning engine oil;

Exhaust pipes for cars with engine oil are usually very white.

3. The oil and gas mixture is good, and gasoline has not completely burned, which is the main reason;

4. In-cylinder direct injection + turbocharging;

With a turbo, the turbocharger engine ’s supercharger speed is very low, and there is little change in the degree of mixing of oil and gas at the start of the turbine, so it is good to control the concentration of the mixture. Because the electronically adjusted fuel injection rate has to be changed to match, some people have done a survey, that is, about 80% of the models of turbocharged engines have black exhaust pipes.

5. Manual start and stop;

There are gains and losses, this function is very convenient, but never stop starting and stopping, the working state of the car is usually not very bad, it is difficult to turn black.

6.Exhaust pipe structure problem (only doubt)

Most of the blackened exhaust pipes have the kind of crimping structure inside the nozzles, so the exhaust pipes are clean, and the nozzles are basically curved; in some cars, the external nozzles are curved and very clean. However, the decorative cover has an inwardly rolled structure, and there is a layer of black ash here; therefore, the whiteness of the exhaust pipe may also be related to the structure of the inwardly rolled, and it is more and more difficult for the curved outlet to discharge exhaust gas. A layer of obstacles makes it difficult to accumulate pollutants.

We should know why the exhaust pipe is black, so how to avoid it?

1. Clean the oil circuit regularly;

2. Strengthen the maintenance oxygen sensor;

Through the following analysis, we know whether the air is sufficient or not is a very important reason. So how to ensure that the air-fuel ratio of the engine reaches or approaches the perfect state? This is to strengthen the maintenance oxygen sensor. The oxygen sensor adjusts the intake air volume by analyzing the oxygen content in the exhaust gas to maintain the air-fuel ratio close to the ideal value. If the data provided by the maintenance sensor is inaccurate or delayed, The air-fuel is higher than the fecal imbalance, so it must not be fully burned.

3. Develop good driving habits;

to sum up

Car fuel is not fully burned, causing carbon deposition is the root cause of whitening of the exhaust pipe. There are two very critical conditions for the generation of carbon deposits: fuel quality and air-fuel ratio.

As we all know, the quality of gasoline in our country is relatively small, and it is difficult to generate carbon deposits. The structure of EFI vehicles also leads to carbon deposits. Therefore, the blackening of the exhaust pipe is really stable.

Although the blackening of the exhaust pipe is by no means a disease, the accumulation of carbon over time will damage the engine, intensify the wear and tear, the power of nature will decrease, the noise will increase, and the fuel consumption will increase. Regular maintenance of the oil circuit, inlet and exhaust system is the best choice to reduce carbon deposits and reduce exhaust emissions.


It is becoming more and more difficult for German cars to generate carbon deposits. What is the reason for this?

This is because the style of German cars is more sporty, emphasizing driving, handling, and speed. Slower and slower accelerations require more and more fuel and air to be consumed. According to the ideal air-fuel ratio of 14.7: 1, the remaining portion of fuel requires 14.7 times the amount of air to replenish. This makes it very difficult to cause lack of air, the combustion will never be sufficient, and carbon deposits will be more.

From the pass rate of exhaust gas detection, German cars are getting higher and higher than Japanese and Korean cars. In order to provide a proper amount of air, turbocharging is a way to use the exhaust gas after combustion to circulate again and burn after pressurization; another way is to increase the compression ratio of the engine and use shorter and shorter intake manifolds to make the unit time There is more and more air entering inside, which promotes sufficient combustion.