I have a 2007 3500 SRW 4x4 with a 5.9. It has a G56 (3.42 gear swap), rockteck, and Quadzilla mileage miser. When the engine is cold, it cuts out over 2000 RPM. It especially does so at around 60 MPH (2100 RPM) in 5th gear. It almost fells like its pulling air in the fuel somewhere, but I know that can't be it since it then goes away. It has been a wonderful truck so far, no problems other than this. I am not new to diesels (all diesel trucks since 1992). I have been reading this web site for many years and this is my first post. The truck is setting no codes and the problem goes away within about 5 minutes after the truck reaches normal operating temp. As long as the RPM's are kept below 2000 until full operating temp, no problems. Any ideas? Thanks, Jay

 

i know that in the autos, when cold, the ecm limits engine power and tranny shifting.

 

I had a 2003 2500 QC 4x4 that would power derate to protect the engine until warm. This is a true cutting out. It's just like on a tractor when air is pulling in the fuel system somewhere. Stumble enough for the rpm's to drop 100 - 150 then catch right back up. I've also checked to see if any water in fuel or condensation in the tank and there is none. It almost has to be computer related or tied to rail pressure until the engine reaches full operating temp. Any help would be appreciated. Jay

 

I would guess air is getting in when the truck is shut off, I would look from the Lift pump back, for loose conection. Maybe change fuel filter also.

 

I just put in a new fuel filter a couple of weeks ago to see if that was the problem. I'll check all of the fuel line fittings. Thanks. If that's not it, what else could it be? Jay

 

i noticed u have the rocktech it might be too much timing when cold for the ecm and it is derating the fuel to protect drivetrain...

 

Thanks Mini 14. I'll adjust it back to stock and see if that cures it. It may be advanced too much with the Quadzilla Mileage Miser. I can't find anywhere loose on the fuel system either where it might be losing prime (even though that is what it acts like). Acts like there's a little air in the fuel line that passes and regains prime after running to operating temp along with lift pump pushing air out.