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Running Rough / Misfire

Problems

Several things could be causing rough running or a misfire in your Cummins Semi:

Problem: Stiction

Solution: Treat with Stiction Eliminator to clean out all of the injectors. Use Diesel Extreme to clean out the fuel system.
diagnose

Problem: Mechanically failing injector(s)

Solution: If the truck continues to run roughly, investigate electrical issues and more serious injector issues.

Details

A condition of running rough can be one of many factors. If the truck runs rough when it’s cold but clears up when the engine is warm, you have a stiction issue in your injectors. Treating with Diesel Extreme will clear out the debris in your injectors. If the truck runs rough only at idle, a stiction issue is likely, so treat this the same way. If the truck is running rough all of the time, it can be a little more complicated. An injector may have gotten beyond the point or our product cleaning it. An injection pump may be failing, or a pump may have gotten out of time. An electrical issue, such as sensor failure, can affect your truck in a similar way. You will need a scan tool to properly diagnose this. The hardest to diagnose is an intermittent miss. It may be best to take the vehicle to a professional, depending on how good you are with your vehicles electrical system. If you have any questions, feel free to contact one of our diesel experts.

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Running Rough / Misfire - Heavy-Duty Cummins Symptoms
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