HELP!! 2006 2500 4x4 5.9 Cummins, 110,000 miles. All maintenance kept up to date. (Has new air filter and fuel filter). Truck has always run great. Pulled a trailer to Calif from Texas last week. It was running normal, then in New Mexico it started losing power (shut down) at about 2600 rpm. If I was accelerating, it would run normal then around 2600 rpm it would blow out a big puff of black smoke, lose all power (as if you turned off the key). When I let off the accelerator and slow down a few MPH, it would start running normal again. As soon as I'd get around 85 mph (in drive), it would do it again. If I kept it around 75-80 (in high gear), it ran great. However, it does this in ALL gears when I hit 2600 rpm. It's like having a governor (except lose of power instead of a leveling off). The first time it happened, I thought it was starving for fuel. However, it always does it at same RPM (whether accelerating slowly, or if pushing it).

Any input would be appreciated!
Richard

 

Any odd lights on in the dash? Had it scanned for codes?

 

Thanks for the reply. There are no unusual lights are on. I have not had it scanned. Good idea. I never considered that (since no "check engine" light was on). I can't do it tomorrow, but will Saturday.

 

The pcm can have 'pending' codes, that won't turn on the light. Get it scanned, see if anything interesting shows up.