Rough Idle

[Diesel Thunder]

Hi all,



My '05 has developed a "rough idle. " Occasionally it has an old gasser with an aggressive cam feel to it---but not in sound (If that makes any sense)? I replaced the FCA recently as I had an intermittent tick under light acceleration, but have now developed this mild "lope" at idle up to around 1500 RPM then smooths out. No knocks/ticks at idle.



Question is: What is causing the rough idle?



I don't do any towing with it. No real excessive idling time. Sees interstate use everyday. Warmed to normal operating temperature almost every time I drive it. No white smoke. No long cranks.



However, does this sound like a carboning of injectors?



Recently changed fuel filters (factory and GDP 2 micron).



I am not seeing any abnormal EGTs. No oil contamination that I can appreciate, although I am running a sample this week.



I am considering using the Cummins C-Premium Plus Diesel Engine Fuel System Flush (Part No. 3885823). The Cummins dealer says that they use it on the large engines that are having carbon issues. The only catch is: the way it works is by allowing the fuel system to "run" out of the 1 gallon can that you buy it in (ie. it becomes it's own gas tank). You let it run/idle for 15 mins, then shut down and pour what is left into the main fuel tank. However, I have no idea how to achieve this with the in-tank lift pumps we have.



If I use it, I plan on running the tank to near empty, filling the factory filter housing with it, then dumping the remainder into the tank, and then idling for 15 mins. Then fill with fresh No. 2.



This stuff is supposed to work wonders on dirty injectors.

----It contains:

1. Petroleum Distillates

2. Organic Amine Oxides

3. Alcohol Derivative



Thoughts?



Thanks for reading...



-Regards.

 

[Prairie Dog]

Even when your tank is close to empty there's several gallons (maybe as much as 5) left in the tank because the CP3 uses fuel to keep itself cool. So by just adding it to the tank, the cleaner will be severely "watered" down IMO.
I would disconnect the line at the tank and jury rig another line down to the container of cleaner.

 

[p-Bar]

I would suspect your FCA failing a quick test is to put a quart of 2 stroke oil in the fuel tank and run it and see if it smooths out . If it does there is your problem

 

[B.G. Smith]

While mine was still fairly new it had the rough idle syndrome but with a little smoke. I took it in and all they did was run some Mopar injector cleaner through it (added a bottle to the tank). Smoothed it out. bg