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Discussion Starter #21
The issue I have with this, is that it seriously limits the performance of the vehicle (I saw large gains with a TCM tune) and having a 2016 and 2014 to compare to, the 2014 ignoring the 3-2-1 issue shifted better in all aspects of performance.

I get that torque management is a thing and always has been, but in every vehicle i've owned its never been so terrible like it is in the Cherokee.
 

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Since the mid 90's (that I know of) manufacturers have been torque limiting. Especially at shifts. This is nothing new at all. As mentioned, even if trans is good for it, the PTU and other parts might not be. It's not like we have a Detroit Locker or a Ford 9 bolt in the rear end LOL. >:D

https://www.hotrod.com/articles/12-bolt-chevy-vs-9-inch-ford/
Toyota is the benchmark child of de-tuning both there Engines and limiting torque to the transmission shits. It part of the reason why there engines and trans last so long. Of course the downside is sub par performance.
 

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Have you ever wondered why your transmission and/or jeep as felt sluggish more specifically the 2016+ years.
I’ve discovered the FCA has been limiting the max torque that the engine will output as a result of torque management from the TCM on 2016 vehicles and presumable all 2016+ Cherokees and Chrysler 200 vehicles.

There are torque management values in both the PCM (Engine) and TCM (transmission) that are set at values to preserve the drive-train, which make sense. What was rather shocking is that the values in the TCM were LESS than what the engine could make.

I have read 2 2016 Cherokee TCMS and both had the lower than factory torque values programmed in the TCM. I”ve also read a 2016 Chrysler 200 FWD 3.6L and its low torque values were EXACTLY the same as what was in my Cherokee TCM.

To recap the 3.2 Pentastar has a torque peak of 239ft/lbs @ 4400rpm
The 3.6 Pentastar in the Chrysler 200 has a torque peak of 262ft/lbs @ 4250rpm

2016 Cherokee TCM torque limit


2016 Chrysler 200 3.6 V6 FWD TCM Limit



Notice how the are exatly the same, super odd....

The first version of my TCM tune had the values restored to "stock like" values




After getting my TCM tuned the factory torque values were put in. This made the vehicle feel much stronger as the vehicle was allowed to make more torque than what it was before. Since I was modified and making more torque than factory, I needed to raise the values higher. I did some further testing and moved up the values even higher to a point that would be higher than my engine would ever produce effectively letting the engine make as much power as It could without being restrained shown below.



The results were very impressive, it literally felt like I had gained another 50hp (I didn’t in reality) but the vehicle launched much harder, downshifts were quicker and the power came on even faster than before. Sadly I was not able to run at the track after these changes due to it being rained out. In terms of times I’m not sure it would have been much faster ET wise but the driving experience was even better.

Now there were a few things I noticed after changing the values much higher. Normally under regular driving I would never really “feel” the upshifts or downshifts. With the values much higher there was a noticeable engagement of the gears and downshifts sometimes gave a hard thud that shook the whole vehicle. Most likely one of the reasons why FCA programmed them the way they did.

What about 2014 and 2015 models? My 2014 Cherokee has always shifted harder and more firm. Prior to my TCM tune on my 2016 I always wished my 2016 would shift like the 2014 did at WOT, it’s always quick and firm. When you take a look at the 2014 and 2015 TCM’s vs the 2016 and up TCM’s there is no option to adjust engine torque parameters in the TCM(like the 2016 and up models). There have been multiple software versions of HP Tuners but for 2014/2015 engine torque is still not adjustable. It may be that these models of transmissions aren’t limiting as much power as subsequent years. One obvious difference between the 2014 and 2016 is the shift pressures on 2014/2015 models are higher than 2016+ vehicles. Additionally torque converter apply/release values are much higher as well. Just a small example of the many Torque converter values that are higher on the 2014 vs 2016



What does it all mean? Probably nothing but I can tell you that after making the adjustments there was a very noticeable difference. I’d just really like to know why they have this torque management built in to the TCM programming. Maybe the higher failure rates of 2014/2015 models could be a result of more aggressive programming?

Also of note there is ZERO of that torque management in the ZF8 in my Grand Cherokee that reduces power below the peak torque of the engine
There's Zero because it uses the Best, tried tested and true, bulletproof 8 speed lateral transmission in the business. The ZF-8 will go down in history has one of the best transmission ever built for mass produced cars. The ZF-8 when specifically tuned, is shifting in Dual clutch speed territory. Granted the regular Grand Cherokee does not get that tune(unless it's a TrackHawk) but that's cause the Grand Cherokee would not benefit from it really since the ZF-8 is already capable of fast seamless up and downshifting.

So let me ask you, is the Torque as limited in the ZF-9 while in sport mode? I am really considering buying the extra ECU unit and acquiring the tune software.
 

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Discussion Starter #24
So let me ask you, is the Torque as limited in the ZF-9 while in sport mode? I am really considering buying the extra ECU unit and acquiring the tune software.
Yes the torque limit is the same regardless of selec terrain position its an overall limit and not specific to the different modes.
 

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Reviving this dead thread. After discovering this thread months ago, it's always bothered me that torque was being limited.

I was kinda bored and checking out TCM tuning (because reasons) and I think I just spotted something important.

Looking at the second to last picture in this thread:

It would appear there's no torque limit when upshifting. Which would explain the extremely rough shifts during heavy acceleration after removing these torque limits.
 

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Discussion Starter #26
There absolutely is torque being reduced.

Just because it's not in that part of the TCM doesn't mean it's not there



Also, that was from Jan 2019 and was my 2016 Trailhawk. I never got a single TCM update on my 2016

My 2014 has 295ft/lbs in those fields

My 2014 ADII Limited and 2016 TH both have 295ft/lbs elsewhere




Just so you know, just because there isn't torque being limited in 1 table there is always torque management elsewhere








The first picture along with some values in the PCM is what made the shifting harder but much quicker on my 2014.

I appreciate the interest in the TCM tuning but there are so many aspects of both the PCM and TCM torque management i'm still learning and working with it.
 

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I'm honestly considering doing this mod. Gaining 40-60 ft-lb of torque for ~$600 is probably one of the most cost effective mods I've heard of on a modern car.

I'd have to figure out how to tune out the slam-shifts though. Those aren't great for transmission life.

Main issue is that I'm on a 2019, and I bet the TCM firmware is updated and likely not compatible with HPTuner.
 

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I'm curious what would happen if you needed a new transmission because of some failure, and you owned a 2014. Would the TCM programming resort to the 2014/2015 torque figures, or the 2016+ one?

Thoughts? @Tyler-98-W68
 
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