I am pulling a 23' toy hauler about 8000 pounds with a 97 cummins 3/4 ton and with o/d off up slight grades i am keeping the truck at 60 mph at about 975 egt's and 10 boost. when i go up a 6% grade top speed is 30 mph 1100 egt's and 18 boost. i just had the transmision serviced about 2 months ago and lift pump and filter replaced 6 months ago along with K&N (round) filter. where should i start to diagnose this problem? I have a buddy saying to check compression and i am thinking tranny (torque converter). truck has 278000 miles on it automatic tranny.

 

I don't think the compression has anything to do with it.If your tranny is a stock auto like mine i would seriously look at the tranny.On the 12 valves they are the weak link,especially with the milage on you truck.Can you be a little more detailed on the problem?

 

sounds like lack of fuel to me. what is done to the truck? was the tranny slippin? is the tranny fluid burnt smelling?

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mine did the same with 12k on a grade.. my fuel plate and boost elbow and afc tune helped alot.

 

4" exhaust, different fuel plate, 3k gov springs, a touch more timing and you will think you have a different truck

question is the EGT reading pre or post turbo??

 

Tranny and fluid is red and does not smell burnt and the tranny was not slippin but is seems to shift to early and that is when i lose all power. The egts are before the turbo. I have been skeptical on moving the fuel plate just because i have heard that the trannies can not hold up to the torque. Thanks for the advice.

 

my stock 47rh handled a 100 plate full forward, 4in exhaust, bhaf, and boost elbow........for 6months

 

doesn't the 97 have the modules in them that have something to so with shift points.

 

Sounds like your tc might be slipping a lil bit

 

Transmission shop says tranny is good and i now have it getting a diagnostic on the engine. they are thinking it might be a sensor. AFU hopefully they can find something out i got to move across country before Christmas.