Black smoke from diesel engine​ is a common occurrence but some people still panic about it. So we often get asked ​what does black smoke from a diesel engine mean? ​ It indicates that the engine has some kind of a problem and basically points to imbalanced fuel and air ratio or a more complicated issue. Normally, diesel engines should not produce almost any smoke while working, however, it’s normal for some older diesels to release some smoke when accelerating under load.

Most common causes of ​black smoke from diesel engine​ include:

  • Dirty air filter. Black smoke indicates that the fuel is not burned properly. The internal combustion process in diesel cars requires a certain mixture of fuel and air. The ratio of fuel and air should be proper, otherwise, the mixture will be too rich, which will result in black smoke.
  • Faulty injectors. The injectors are an important part of your fuel system. They should open and close at a particular time and if that does not happen or they are clogged, they will end up injecting much more fuel in the cylinder. This faulty process forms solid carbon residue, which causes a ​black smoke from the exhaust of the diesel engine when accelerating your car.
  • Dirty EGR valve. The EGR helps to re-circulate the engine emission by returning them to the combustion chamber and not sending them directly to the exhaust emission system. The carbon chucks could clog your EGR valve, which will result in loss of power, fuel inefficiency and emission of ​black smoke from your exhaust​.
  • MAF Sensor. It’s also important for the computer to measure the right amount of fuel that should be injected in the cylinder. The Mass AirFlow Sensor is responsible for the proper formation of the fuel and air mixture in the engine. If there is something wrong with it, it will register more airflow in the system and an additional amount of fuel will be injected into the engine. As a result, unburned fuel will turn into ​black smoke from your diesel engine.

How to fix the black smoke from diesel engine when accelerating?

So far, we have concluded that the black smoke from a ​diesel engine exhaust​ is usually caused by bad fuel/air mixture. To prevent further damage to your car, it’s important to take care of the issues as soon as you notice anything wrong. This will save you money and headaches.

There are several things you can do when you notice​ black smoke coming out from your exhaust:

  • Always ask a specialist. The Motor Company’s authorized service can help you with any problems with your diesel car.
  • Clean the air system. As we have mentioned, the right amount of air is important to run your diesel engine properly, otherwise, the fuel will burn only partially. If your air filter is dirty or clogged, you should consider cleaning it or even better – replacing it.
  • Check your engine rings. If the engine piston rings are damaged, that can cause ​black smoke from exhaust when accelerating. ​ You want to make sure that that’s not the case by checking them in an auto repair shop, and if necessary – replace them. This will prevent the black smoke too.
  • Check the fuel supply. The timing of fuel injection is important too. If the injected fuel is too much, incomplete combustion will occur. The right action is to have the fuel pump and the injection system inspected by a professional mechanic. It’s also a good idea to upgrade them with a ​common-rail injection system, ​ which feeds fuel directly to the solenoid valves. This way, the car will produce less ​black smoke out of the exhaust.
  • Use fuel additives. Driving a diesel car daily with a regular fuel could cause a debris build-up in the cylinder chamber and fuel injectors. This will result in a lower performance of the engine and therefore, a lower fuel economy. That’s another thing that causes more ​black smoke from the exhaust when accelerating the vehicle.

​ So, as a conclusion, consider mixing diesel fuel with a high-quality fuel additive. This way, the fuel will not form deposits in the engine, which, in result, will not emit black smoke