Running Rough / Misfire
Several things could be causing rough running or a misfire in your International Semi
Problem: Mechanically failing injector(s)
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 Stiction Eliminator will clear out all of the stiction gumming your injectors. We also recommend using Diesel Extreme to clean out the fuel system on your truck.
If the truck runs roughly 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. A severe case of stiction will cause a vehicle to spit and sputter consistently. This can be treated like any other stiction issue. These symptoms can also mean that there is an injector that has broken, beyond the point of our product cleaning it.
An electrical issue, such as a sensor failure (e.g., ICP sensor), 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. The FICM can cause an intermittent misfire; it is common to see a misfire between 45 and 65 mph when a FICM is failing. Visit the FAQ section of www.ficmrepair.com, scroll down to “Can I test my FICM to ensure that it is the culprit?”, and follow instructions on self-diagnosing the FICM. If the FICM looks good, it may be best to send 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.