Greetings all, had something weird happen last night. It was about 15 degrees, truck was running AOK. Parked the truck for about 2 hours, then went out and started it up. It ran rough, like it was only running on 5 cylinders. I sat there for about 5 minutes, and it was still rough. I then drove it for about 5 minutes, and it cleared up, and has run fine since. No trouble indicators at all.

Should I get it in to the dealer or just wait and see ?

 

Personally, with the luck I have had previously when taking my truck in for service, I would wait and see if it happens again. I assume the fuel filter is clean, no water in separator and you are not anywhere close to running out of warranty.

 

The filter has not been serviced yet (10k) and there is no water in the filter. This problem has now happened 3 times. The last 2 times I shut it down and re-started and it was fine... Again low temps 0-15...

 

I've had something similar happen at least 4 times -- truck runs really rough like it's running on only 5 cylinders. I live in Southern California, so I can't attribute it to low temps. Each time it's been on a restart -- times during shutdown varied from 15 minutes to 3 hours. The amount of time it ran rough has varied from 3-4 minutes to 15 minutes and the last time I drove it for about 10 miles, shut it down and then it cleared up on the next restart. I've also gotten the Malfunction Indicator Light on the dash each time.
Also, each time it's thrown the code P0304 which indicates cylinder 4 misfire.
The first time it happened I thought maybe it was due to a fuel additive I was trying - Valvoline SynPower (which claims it was developed in cooperation with Cummins) but it happened at other times as well without a fuel additive.
I've had it to the dealer twice and they have been unable to replicate the problem. They agree with the code and the misfire, but other than driving it and hooking it up to the computer, they refuse to do anything else. I suggested they remove the injector and try some analysis, but they don't want to do any "easter-egging" that DC won't reimburse them for. Obviously there's something wrong with cylinder 4, but what?

 

I hear ya... Mine is not throwing any codes at all... I would dwear that it is a sticky injector, or possibly something electrical... It is concerning though....

My main worry, if in fact that one cylinger is not firing, is that fuel is likely to wash down that cylinder, and it will wear much faster than the others.....

 

I see this thread is 5 years old now. Did anyone ever find a fix for the rough running engine? I am having the same symptoms as F11Engineer, including the same DTC, P0304. What did yall do to fix it?