Why Is My Car Blowing Black Smoke When I Accelerate

If you are accelerating and your vehicle is blowing black smoke from the exhaust, this is something that you should look into and fix the issue. But, you are probably asking ”why is my car blowing black smoke when I accelerate?”

”Your car is blowing black smoke from the exhaust when you accelerate because the engine is fed more fuel than air. An inaccurate fuel to air ratio will result in more fuel burned in the combustion chamber than needed, therefore, black smoke will appear from the exhaust pipe when you accelerate.”


Why Is My Car Blowing Black Smoke When I Accelerate

Why Is My Car Blowing Black Smoke When I Accelerate

When black smoke appears from the exhaust when you accelerate is usually associated with incorrect fuel to air ratio. Meaning, some of the vehicle components have failed and now the engine is fed more fuel than air. Having more fuel than air into the combustion chamber results in black smoke exiting from the exhaust pipe.

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At this point, theoretically, you can drive your vehicle but you shouldn’t. Not getting to the bottom of this issue can only cause permanent damage to the engine. You should address this issue because it could be something that you can fix under $100. Here are the 10 most common reasons why your car is blowing black smoke when you accelerate:

1. Clogged air filter

A clogged air filter prevents air from flowing into the engine. When your air filter gets clogged, there will be more fuel to air ratio therefore causing a rich condition and smoke out of your exhaust when you accelerate. Changing out your air filter is something that you can do. Here is how to change your air filter.

2. Leaky fuel injector

A fuel injector that is stuck in an open position will increase the fuel amount that is entering the combustion chamber. This will cause more fuel to air ratio and cause black smoke from your exhaust when you accelerate.

3. Faulty fuel pressure regulator

The function of the fuel pressure regulator is to maintain stable fuel pressure going into the fuel injector. When a fuel pressure regulator fails, fuel pressure would be higher than normal, therefore, causing more fuel to air ratio.

4. Faulty upstream oxygen sensor

A failing oxygen sensor (o2 sensor) can provide inaccurate information to the engine control module (ECM). With that inaccurate information, the computer will think that more fuel is needed and will supply the engine with more fuel. This will result in burning more fuel than needed and as a result, you will see black smoke coming from the exhaust. You can use a scan tool to verify that your o2 sensor is faulty and replace it.

5. Faulty mass air flow sensor

A dirty or faulty mass air flow sensor can cause a rich condition by providing the engine control module (ECM) with the wrong information about incoming air. Cleaning the mass airflow sensor might help improve the functionality of the mass airflow sensor. If cleaning does not solve the problem, you should go ahead and replace the sensor.

6. Faulty map sensor

The MAP sensor (manifold absolute pressure) calculates the air pressure in the intake manifold. The manifold absolute pressure is located on top of the intake manifold in the engine bay. A faulty map sensor will provide your computer with the wrong information and the computer will send more fuel into the combustion chamber. If the map sensor is faulty, you should replace the sensor.

7. Faulty coolant temperature sensor

When the engine is cold at startup, more fuel is sprayed into the engine until it reaches the normal working temperature. The temperature sensor measures the coolant temperature. However, if the coolant temperature sensor is faulty, it can no longer measure the temperature of the coolant and more fuel will be sprayed into the combustion chamber resulting in black smoke coming from the exhaust.

8. Faulty air intake temperature sensor

The intake air temperature sensor measures the temperature of the incoming air. It helps calculate and regulate the amount of fuel added or restricted. If the air intake temperature sensor is faulty, it can no longer measure the temperature of the incoming air and will provide the ECM with inaccurate information.

9. Overfilling engine with oil

Putting too little oil in your engine could definitely damage your engine. But, putting too much oil in your engine could cause it to smoke and cause severe mechanical damage as well.

When you overfill your engine with oil, the engine oil ends up getting past your oil ring, and your piston rings. From there it gets to the top of the cylinder and it goes into your combustion chamber and then burns off with the air-fuel mixture. After the combustion is done, the smoke that will exit through the tailpipe will most definitely be black.

You should park your vehicle on a leveled surface and check your engine oil level when the engine is cold. If you have more oil, make sure to drain some in an oil pan.

10. Engine is burning oil

This usually happens on engines that have a lot of miles on them, or I guess on engines that have not been maintained properly and haven’t had their oil changes done on time.

What happens is your piston rings and your oil rings wear out and they cannot properly clean and scrape down the oil that gets on the cylinder walls. The leftover oil gets into the combustion chamber and gets burned off with the air-fuel mixture and black smoke gets emitted from the tailpipe.

Is Exhaust Smoke Normal

White or black smoke from the exhaust is not normal. A fully operational vehicle should not have any color smoke. If your vehicle is emitting black smoke from the exhaust, it means that the engine is getting more fuel than air. A correct fuel-to-air ratio is necessary for an engine to operate normally. White smoke on the other hand is associated with engine burning coolant. If you see white smoke from your exhaust, you should first check your coolant level and then take your vehicle to the repair shop.

Igor Iwanowski

I am a certified Automotive Service Excellence (ASE) mechanic since 2018. I specialize in Brake systems, dashboard warning lights, EGRs, general engine problems, EVAP and Emissions issues.

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