Gen 3 Ram 8HP70 swapped

[TylerR]

I have a 2003 Dodge Ram now running an 8hp70 that I just completed the swap in. The trans has a stock SRT calibration and I haven't messed with any of the parameters but it is all over the place with it's shifts and really doesn't like to downshift. I cannot find any info if it is possible to do a quick learn using HP tuners so I can get the CVI set, it shifts perfect in manual mode but takes a dump once I move the shifter over to drive. Keep in mind this is an original truck transmission and I sent the TCM out to have the SRT calibration put in, there is no way the CVI can be right and I'm scared to drive it until I can do this.

[EVguy1]

I'm not sure you will get any help. I'm in the same boat and asked a lot of questions with little response. As soon as you mention you have a swap I think everyone thinks liability or something. I even contacted two tuning companies who both declined. I thought I could figure it out but have not been able to after a few months of trying.
I have upshifts not bad but it hangs in 6th way too long when I come to a hill. Did you use the SGA/PCS module?

[TylerR]

Yes I have the SGA kit. I have reached out to a couple of prominent tuners and waiting for a reply.

[james1595]

i feel like the dodge guys just dont like helping. ive been asking for for help with my trans tune for like 6 months and nobody seems to want to help. id like to help, but i dont know if i could. i can try though. i can give you my stock trans tune and you can look at the differences, although i do have a challenger not a 1500

[EVguy1]

That's a great idea james1595, here is my stock ram 1500 5.7 trans tune as a starting point.

[Adam K>]

A big part of the issue is that most tuners are just not familiar with these conversions. Adding a secondary OBD port complicates things even more.

I can almost guarantee 90%+ of your issue is in your engine tune. The 8HP transmissions use aggression counters to determine which shift ID to use at a given time. In normal mode, for example it has 5 shift tables. 0,5,10,15, and 20. When going up a hill you are in either 15 or 20. Depending how steep and engine load the NV ratio changes as well. You can't log NV ratio using the PCS OBD however. Can only be done on the Engine side.

What is basically happening is your car is reporting the wrong TPS signal and in turn engine load and torque. There are many factors that affect how much your throttle opens. With my car, full Hellcat Engine and Transmission on a 2012 Chrysler SRT8. Instead of redoing the entire engine tune, I made changes to my driver demand tables to be as close to a Hellcat as possible. I also put my throttle body airflow numbers back to stock even though I'm running a Hellcat throttle body. Prior to this my car would hang in gear till I lifted or went into WOT. It?s shifting really nicely now. It's still a work in progress, but it's really something that I will need to continue to log and make small changes to see if it improves even more.

throttle.jpg

[james1595]

in hp tuners, im seeing that both ecu and tcm are from a 2014 1500. so does that mean the motor was swapped as well? if so, that could make it much easier to work with being as its a tune problem, not a communication error

[EVguy1]

If your referring to the two files I had attached they are the stock files from my 2014 ram 1500 that I was offering as a starting point for TylerR to use. My swap is a Cummins 4 cylinder in front of the stock ZF8. The ECM has been lobotomized and just runs the dash but until I can get the ECM to "start" it wont allow other systems to fire up. I have been driving it for 6 months with a second key that starts the Cummins and hope one day to get the RAM start button to work again. Mine is a communication problem.

[james1595]

ok. i was just wanting to be certain before i said something incorrect. but unfortunately, im not sure how to help you. the 8hp70 transmission basses its shifting off throttle position and input shaft speed. it also uses torque calculations from from the ecm, so if there is no communication between the two, it wont work properly. now im sure theres a way to fake numbers and trick the tcm, but i dont have a clue. wish i could help more

[EVguy1]

The Cummins ECU is sending some info to the TCM like RPM, TPS and tq.
I would love a bit of help with some of the basic ideas so I can learn this but I don't want to hijack this thread. Would you mind answering a couple of questions on my thread? https://forum.hptuners.com/showthrea...-shift-mapping
One thing I don't understand is how to increase engine braking under throttle lift.

[DodgeBoy_8HP]

Hello,
I could help you with the transmission tunning. I have more than 10y of experience with ZF transmission.
Please, send me an email: [email protected]

Thanks.
Dodge Boy