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Reasons Why Your Diesel Engine Is Sluggish


When your diesel-powered vehicle isn’t performing up to standard, something is wrong. But pinpointing the cause of its diminishing power isn’t always simple. Multiple things could lead to the reduction of power in a diesel engine. Some of them are more common than others. If your diesel engine is struggling or performing poorly, let’s check out some of the top reasons why your diesel engine is sluggish and how to fix them.

Video Overview

Dirty Air Filter

A clogged air filter will restrict air flow to the engine. This can result in the air-fuel mixture being too rich. As a result, you might notice black smoke coming out of the tailpipe. To avoid this problem, make sure to clean and replace the air filter at the recommended intervals. A diesel engine should have its air filter changed every 30,000 miles—that’s every three years.

Worn or Dirty Injectors

Another reason why your diesel engine is sluggish could be worn or dirty injectors. The engine’s fuel injectors are sensitive to clogging so the smallest amount of dirt can affect their spray. This can lead to your engine running lean, which means it’s igniting with either too much air or too little fuel. Even smaller, simple things—such as engine varnish and tank sediment—can cause your injectors to clog. The easiest way to fix this issue is to clean or change your fuel filter when you notice a reduction in performance. If your engine is still performing sluggishly, you might have worn-down injectors that need to be replaced.

Malfunctioning Turbocharger

There’s a good chance your engine is equipped with a turbocharger. If your turbocharger is malfunctioning, it can lead to reduced performance and noise. It might malfunction because of a lack of lubricating oil, debris in the system, or bad seals. It’ll make a high-pitched whine and might even turn on the CEL. You can drive with a blown turbocharger, but it isn’t recommended: the longer you leave the problem alone, the worse it will get. If you suspect your turbocharger is failing, have it inspected and repaired as soon as possible.

Compression Issues

To properly combust fuel, the engine relies on the correct compression ratio. If there are problems with the rings, valves, or other components, the ratio can be skewed. Normal wear and tear is enough to cause this, but other reasons for an unbalanced compression ratio include a blown or leaking head gasket, or a cracked head or block.

A loss or reduction in compression doesn’t need to affect the entire fuel system before it starts causing problems. A single cylinder that’s operating under the wrong ratio can cause your vehicle’s performance to tank.

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