Transmission Tuning

Hello to all,

I hope their are some diesel transmission guys active on here that would be willing to lend a hand. I have a 2018 Ram 2500 Cummins with the 68rfe transmission. The truck has been deleted and tuned using EFI Live and the transmission has an upgraded valve body. The valve body consists of a Transgo oversized SSV valve, Transgo upgraded LR valve, Transgo programming kit for better shifting characteristics, upgraded revmax separator plate, and 225 line pressure mods. The issue I'm having is no tune file i try works with the transmission. Currently the upshifts are aggressive and 2-6 upshifts drag out kind of like riding the clutch in a manual setup. When slowing down their is no downshift and when coming to a stop if the transmission is in 3rd the truck sounds like its going to stall and then a loud clunk sound and the rpms level back out. Their doesn't seem to be as much power then before i don't know if the tune was a mild tune or if the torque converter isn't going bad allowing all the power to the rear wheels. If anyone has any advise or incite or knows where to find some info regarding my issue please let me know. Thank You

You've made several contradictory statements there - might be an idea to edit the issues and list them individually, for clarity?

First thing I would be checking is if the shift kit was correctly fitted - modern transmissions are incredibly complex compared to the old 350/400s', and an incorrectly placed check ball, or sticking shuttle valve, or poor electrical connection will cause all sorts of issues.

However, it'd be easier to start with checking all external electrical connections, checking the actual line pressures, etc, before dropping the bottom plate. Oh, also check the correct transmission fluid was used, and the level "by the book".

I think it was the way I worded some of that is why it didn't make since after reading back over it sorry about that. When I say before I mean the guy that installed the valve body his tune is the only one that has worked so far but their was a shutter at 2-3 upshift and a few other thing that needed adjusting but I couldn't get him to do a revision or look at the issue so I had to go elsewhere to try and fix it. Without any guideline tables or anything to go by nobody knows how to set the parameters to make the transmission happy. Checked wires on external connectors cleaned grounds the correct fluid was used or at least I was told that level is ok as well. Off the top of my head I can't remember line pressure but I do have a data log and looking at it should the output shaft speed be way different then engine rpm cause they vary sometimes as much as 1000 rpm

Hmmm, TBH, that the guy that "did" the rebuild isn't prepared to look at the transmission issues, and help resolve them, is a MASSIVE "red flag" to me - I may be unfair, but sounds like a cowboy who just wanted your money and doesn't give a damn about his customers.

I honestly would have strong suspicions he was incompetent, that HE knows he did something wrong, and that's a big part of his avoiding taking the required actions to remedy it - he knows it's going to cost him time and, probably, money.

It's not something you're going to want to hear, but the best and, long term cheapest, option would probably be to send the transmission to an actual REPUTABLE auto' transmission specialist to check his work over. Someone may be able to guide you to one in your area, or you may need to send it off, which is a bugger if it's your daily'. What town/city are you in, as the company may even be able to direct you to one of their registered/specialist installers - https://transgo.com/ - their contact details are at the bottom.

Do you mean transmission input speed being different from the engine, or the engine speed varies for the same output shaft speed - road speed in the same gear? If the torque converter isn't "locked up", there will be variations in the 'slippage' of the torque converter, depending on load and speed, with it most noticable at low engine rpm.

There are some very smart chaps here, who have experience of these transmissions (I'm a manual guy!), and I would hope some pop in to give some actually useful advice.

Correctme if I'm wrong I don't know if your familiar with the efi live software or not but the upshift and down shift parameters are based off of the transmission output shaft speed and the throttle position. That's how I noticed the engine rpm was significantly different then the engine rpm. Thinking of it as engine rpm isn't the way the output shaft speed is read. Having to take into consideration of the converter stall the gear ratio plays on those numbers making them vary like they are. Is this correct or no? I'm kind of learning things as I go so if any of this information is incorrect please correct me I'm new to all of this and where I'm located their isn't any shop or business that specializes in tuning that's why I'm in the boat I'm in now. Trying to learn how to tune and fix my truck at the same time hasn't been the easiest nor the cheapest but don't really have any other options at the moment other then buying tunes offline and relying on someone else which is what got me into the situation I'm in now. It's turned into a headache and a nightmare but with time I'll get their just wish their were some things online to help me understand it better but content for tuning is very limited and no one is willing to help or share any advice

Ah, sorry, my error, there are three basic rpm measurements - the engine/input to the torque converter, the output from the torque converter/gearbox input, and the gearbox/tailshaft out-put.

Tailshaft should directly correspend to the vehicle road speed, as that's a fixed relationship. Input to output shafts' rpms ratios should be fixed for each gear, unlocked there will be varying amounts of "slippage" across the torque converter, but when "locked" it should be stable.

I think you will be wasting your time with "tunes", because I don't think the transmission was put together correctly, and/or there is a different underlying issue. I may be wrong, but that's definitely what I think the base problem is, and until that's either confirmed as being correct, or corrected, no "tune" will ever cure your issues.

I understand you may have a problem finding someone to look at it, but there may be folks reading this that can advise, or help, if you give your location - and did you try the manufacturer for assistance finding one?

I had a look for fitting documentation - the guide to doing the work - for you to go over it yourself, or with a friend, but couldn't find anything on their site. it's possible they can supply a PDF for the installation, and a test/diagnosis work-sheet.

I'm located in marion va and I have a pdf file showing a complete breakdown of the 68rfe and a install pdf for the valve body I myself have never got that far into a transmission so I'd be a little hesitant on pulling the valve body myself I feel like I'd be gambling with about $7000 and my luck is the worst so idk what to do I'm honestly fed up with the whole situation. Thanks for your help I guess I'm going to have to sit back and reevaluate everything and see what my best plan of action is either way it's not going to be cheap or easy

Sorry I can't be of any real help, but in the meantime, you may wish to check out these shops - https://www.yelp.com/search?find_desc=Transmission+Shop&find_loc=Marion%2C+VA

Do some research into people's experience with them, and when/if you narrow it down to, say, five, call them and see if they'd be interested in taking you on. One potential issue is that businesses usually HATE re-doing/checking other people's work and/or will charge a premium for doing so - that's a big reason you need to check them out carefully.

If one, or more, is on the TransGo dealer/agent list, they may move up the list.

Scary thing is, depending on whether the previous chap did the job competently, or was a butcher, it could be anything from a few hundred dollars to sourcing a new s/h core and going from there, which could run close to 5 figures - but on the plus side, it should come with a warranty.

I wish you luck, and maybe a winning lottery ticket to pay for it ;-).

With how the truck is running with different tune files to me a lot of my issue is in the tune file. Being a green horn to the whole tuning aspect of it and the lack of online support what plan of action do you suggest I take as far as fixing that. I'm not saying their still isn't something wrong internal but if I do get the issue fixed these crappy tunes you buy offline aren't the greatest tunes in the world. The engine side of it their is minimal support but their is some out their but the transmission side their isn't any support and with efi live they use the throttle position and output shaft speed parameters when adjusting the up and down shift points. Output shaft speed is totally different from engine rpm. I know their is a way to calculate in order to get that value I'm just not 100% on how to achieve that