t800 w/n14 celect derates power

Hi, I have a 97 t800 that i have been sporadically fighting what seems to be a power derate issue. I pulled a 116,000# load for an hour, dumped the load, and then darn near could not make the trip home empty. No lights, no active or in-active codes. The truck would lose power to 1,500 rpm. I could then ease into the throttle, then it would lose power again. Any ideas??? Thanks.

 

thanks, but have a brand new filter just installed. also swapped out the cam position sensor with a working unit. same thing on today's load, except i could not get the rpm's above 1,700. i have a 4 wire speed sensor on the back of the transmission, and i am going to try swapping the pairs going to the speedo and the engine computer.

 

Sorry, i neglected to say that my truck has an N14 celect plus also. I just ran another load yesterday after swapping in a good speed sensor. The truck still would pull to 1,700 then cut back to 1,500. It also does it under cruise control, so that should eliminate the throttle position sensor on the foot pedal.

 

Yes. This is where I am at. New fuel filter (actually 3). Vacuum tested fuel suction line. Swapped out camshaft pos sensor, speed sensor on back of tranny, boost sensor. Tonite I swapped out the ambient air sensor. I'll give that a go tomorrow.

 

Thanks for the input. the temps checked out ok. The air sensor did not work. The only thing that is going right, is that at least the problem is consistant. I have hauled a load a day for troubleshooting purposes, and as long as I do not load heavy enough to need power above 1,700 rpm (where it tachs out and loses power with a load) i can get it to town where a mechanic can put insite on it.