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Diesel Vehicle Making Lots of Black Exhaust Smoke?

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Are you wondering if your diesel vehicle is supposed to make that much dirty, black exhaust smoke?
Well, yes and no.

Why Do Diesel Engines Smoke So Much?

If you’re behind a vehicle that’s omitting tonnes of black exhaust smoke- (the kind where you want to cover your nose until it disappears) you may wonder if that’s normal of diesel vehicles.
Diesel engines are known for creating more smoke than a gasoline engine. Diesel fuel is actually injected just before the power stroke. Without a good amount of oxygen, the fuel in a diesel engine can’t burn completely- and you’d likely be looking at an incomplete combustion. If more fuel is injected than air available, then the black smoke begins.
Diesel vehicles are absolutely more prone to creating excessive exhaust smoke. The map of many diesel engines produce more power than their gasoline counterparts, but result in too much fuel being pushed into the cylinder.
It’s like the ying and yang of diesel engines.
There’s other reasons why your diesel engine could be creating a lot of exhaust smoke. Faulty injectors, or a bad injector pump, bad air filters or even a faulty EGR valve or turbocharger can create a lot of exhaust smoke.
(Pro Tip: It’s not just black smoke created in a diesel engine. They also produce white and blue smoke.)
Regardless of why diesel engines can create so much exhaust smoke, you likely just want to find out how to stop it. And that’s fair. No-one really loves being around an over smoking exhaust pipe.

Can I Stop My Diesel Engine from Smoking? (And 4 Reasons Why It’s Doing It)

Well, we can’t tell you that- but we can tell you how to reduce it.
If the environment and drivers around you aren’t enough for you to look into the issue, your wallet will. Excessive smoke from your diesel engine will end up costing you- in terms of lower fuel mileage and an almost inevitable repair bill down the line.
So, together with an experienced technician, work with your local diesel repair shop to address common causes of over smoking.

Your Air Cleaner System

If lack of oxygen really remains the root cause of diesel engine smoke, then taking a look at your air cleaning system is 100% a great idea. A good running engine burns all of the diesel fuel completely, creating co2 and water- not black smoke. If the right amount of air isn’t getting in, the fuel isn’t going to burn quick enough.

Turbo charger

This is more for trucks, and older ones at that, because this is inherently a design problem. But, if you’re driving an older diesel truck, your turbocharger is definitely something you should look into.
Creating power to accelerate from a stop, older diesel trucks use huge turbochargers- but these take long time and a lot more fuel to do so. While idling, the turbocharger is often engaged to try and prepare to power the vehicle to move. Referred to as “rolling coal”, pre-activation of the turbo charger only adds an unwanted amount of fuel to an engine with lower RPM’s.
(PSA: Don’t try fixing this one at home. It’s pretty technical to try and address this one.)

Faulty Fuel Injectors

Clogged or worn down fuel injectors will seriously impact the atomization of the diesel fuel. In other words, your engine isn’t going to perform at it’s peak when the fuel hasn’t been processed the way it needs to be.
Think of murky fuel, or unfiltered fuel. That contributes to the black exhaust smoke that smells overpowering to you and everyone around you.

Your MAF Sensor is Off

Even if the right amount of fuel is coming into the engine, your diesel vehicles computer system might not actually be registering it correctly. If it’s reading it wrong, the ratio between fuel and air will register as incorrect and result in an excessive amount of fuel being injected into the engine.

You Can Reduce Your Exhaust Smoke

An experienced diesel repair shop should be able to diagnose and remedy the engine’s issue fairly quickly and swiftly. Hunting for the cause of excessive diesel smoke can be labor intensive for you at home, and it’s a problem you really do want to address sooner than rather later.