Jim Shulmister

A friend of mine has a 98'12v 4wd automatic and lost a trans while on the road. He had it built at a little mom and pop place and ever since has had no power. I didnt understand what he meant until i drove it. While putting around with very throttle doing 800-1000 rpm's all seems fine, if you start to put any foot into it the rpm's jump to 2600 like a gasser when it kicks down to passing gear. It does not seem to be slipping, just out of any performance and rpm range of the engine. He has had it at several trans shops and done all kinds of fixes (New converters) ,scans come up with no codes. The guys at the trans shops say its ok, but they dont know the cummins evidently. It acts like a perfect gasser trans, did they mess and install gasser parts? will they even fit? Any ideas will be greatly appreciated.
-Jim-

Rare1

"It does not seem to be slipping, just out of any performance and rpm range of the engine. He has had it at several trans shops and done all kinds of fixes (New converters) ,scans come up with no codes. The guys at the trans shops say its ok, but they dont know the cummins evidently."

The first question any sane owner will ask at the transmission shop is "Do you know what you're doing?" Dodge did not match the transmission stall speed to the torque band of the engine, and apparently your trans shops know even less than Dodge. There are some that do, you have to ask.

Dufrain

The converter has too high stall for the diesel rpm range.It came stock that way since its made more for the v10.The aftermarket one they put in at the little shop must be lower quality ot higher stall or both.Only thing to do is get a better lower stall torque converter from one of the sponsors here and a reprogrammed valve body.All the power and torque just gets turned to heat.

Jim Shulmister

At the second transmission shop they changed the converter. I was thinking he should put in a performance valve body (I believe thats what controls the shift points), but im not a transmission expert, plus i was worried that if it were a speed sensor/tps/computer related problem he would be out all that money on my advice with the same problem. I disconnected the TV cable and there was no difference at all.
-Jim-

j-fox

Explain the fact that it is no different with the TV cable disconnected?
Do the shift points change?
When you come to a stop and sart again , is it in 1 st? When you start off try this, roll forward a length or so then pull the shifter to 1 st. Does it drop down a gear? If so it is in limp mode.
I suspect they reassembled the TV assembly wrong.
With out it in front of me it is hard to diagnose it.

MnTom

If you sak that qestion like that, they will always say "Of course. We do them all the time". No matter what their experience is. Either that or they just might tell you to park your truck someplace dark and stinky . Just be sure you discuss the situation and go with your gut feeling.
Tom

Jim Shulmister

I will call him tomorrow to test the start-off, if it was in limp mode, there would be codes? There are no codes according to all the trans shops he took it to.
-Jim-

Dufrain

Unless the trans shops install a torque converter specifically designed to be behind a diesel, as in a lower stall, it will always rev up but worse since the cummins puts out as much or more torque at 1800 rpm as a regular gas does at 4000rpm .That raises the stall even more.Any stock 160hp cummins with a stock tc or some other rebuilt gas tc will rev up to 2000 or more and never drop rpm through the gears until the tc locks up.Any engine mods and it just gets worse. Try one of the vendors here for a good diesel tc and valve body its the only way to get the power to the ground.

Jim Shulmister

I am told that the torque converter in stock form does not lock up in first and second. He has owned this truck since 1 yr old and everything was good until the tranny break/rebuild so i believe it must have been stock. It went to a second trans shop when it got back into town and they replaced the torque converter "special order" with a high perf one. The truck has most of its trouble in first and second when there is more throttle pressure to accelerate. It has gone to 2 more trans shops since for advice. The tv cable disconnected makes no difference at all. It will not downshift if you roll a length or 2 and downshift manually. It drives like a gas transmission, it actually kicks down when you accelerate allowing the engine to go to 2500-2700 rpm's before allowing the engine to grab. It does not feel like it slips at all, just like an old trans-am getting on it type shift feel, but no rpm's left in the engine. I get the feeling its got a v-10 valve body in it or something, I just dont feel comfortable advising this guy to buy a valve body when i do not know enough about these transmissions to be accurate at all.
-Jim-

Dufrain

It may be a v10 programmed valve body in there and the performance tc you talk about may be for a gas with an even higher stall.Alot of performance tc have even higher stall than stock. Anyway if you want to find out whats wrong call the number on this website http://www.dieseltrans.com/ they are regarded as the best around . Let us know what it ends up being,I think they stuck a rebuilt trans in there with a gas truck valve body and a tc that has a hi stall. I bet they tell you you need to change the vb and tc.good luck