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The shift is tight and crisp, no flare issues. It feels like the clutch isn't being feathered on the 2-3 up-shifts like it feels on the other up-shifts. It's only in Manual mode, I failed to mention that before, and is only on the 2-3 up-shift. Regular Drive mode and Sport mode feel fine.

Links do not work.


As for changing the tuning to reset the adaptive learn, that happens everytime you program the computer. Either switching the tunes or making any advanced changes.

Ron

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Sorry for the dead links Ron (I can't post links?) If you copy and paste the links, they work

or you can go to G8Board.com and search "Downshift Lashing", or "Superchips Downshift" to pull up some threads about the issues some are having.


One of our issues, is the 6-3 downshift taking longer than other shifts, and it being somewhat "harsh" when it does shift. My other issue is the abrupt 2-3 up-shift in manual mode at WOT. It's not like any other shifts. Drive and Sport mode shifts 2-3 perfectly, it's only happening in Manual mode.


And are you sure that tuning resets the adaptive learn every time we program the car's computer. Some have stated that the Cortex does not do this.

Thanks again for your help

No one I know of would have suggested to take the car to the dealer for a shift relearn.
I do not know why anyone would have said this.
We all (tech support) should know that this transmission takes about 100-150 miles for it to relearn after tuning.

Their is no way that the tuner can prevent the computer to relearn after reprogramming.

Ron

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Ok, back to the issue.

6-3 down shift issue, any comments?

The 2-3 WOT (low RPM) shift issue, any comments?

Thanks

The tuning does not change the downshifts in the trans.

We reduce torque management in the tuning so it can feel awkword , hopefully someone with this vehicle will chime in on their experience.

I can say that we have not had any issues with the trans tuning that we have had to adjust for our customers since the tuning was released.

Ron

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quote"There are known issues and Tech Service Bulletins (TSB) from GM about delayed or harsh upshift/downshift. This may or may not be your issue.

Here are links to the TSB bulletins I posted online. If this is your problem, I suggest flashing back to completely stock original. Then go to a dealership to have the warranty service done, it may be a special reprogram from GM of the computer or some parts replaced.

Then redo your Cortex tune.

#PIP4395C: Flare And/Or Harsh 2-3 Shifts (Nov 19, 2008) - keywords bump delay second slip third

08-07-300-042 - Intermittent check engine light, transmission shift concerns
Web://www.box.net/shared/7nq7kv5onl8lcv70yp9v

08-07-30-036 - Delayed downshift "flatspot"
Web://www.box.net/shared/7btdranbe46npy44v32y
Quote from username= tomprescott
Do a search on the site for "lurching"

Ron

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"hopefully someone with this vehicle will chime in on their experience."

There are many who would like to post, if they would only get a confirmation email to register on the forum. Several have signed up, with no confirmation email for them to long in and post.

Quote from username= tomprescott


Do a search on the site for "lurching"

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Hey Ron, sorry for being late to the party, couldn't get my user name to register, like many other users on the G8 board who want to chime in as well...

To begin, let me say my vehicle has had the 2-3 trans shift TSB performed by a GM dealer, so there is no internal issue. Having said that, my vehicle also has the 6-3 downshift boom or lash AND the jerking 2-3 shift as SRG states. This is not a product of letting the tune relearn, as you say. I had the tune on my car for around 8 months before the 6-3 issue developed (the 2-3 jerky shift was constant). When it did, going WOT from 60+ caused an audible boom or lash you could feel throughout the entire vehicle, which is something I had never felt before. Some people describe it as, "felt like something was going to break".

I reflashed to stock and all the shifts felt better (the 2-3 shift did not jerk into gear ever with stock). The 6-3 shift still had the audible boom/lash, though. I took the car to my dealer, who performed an adaptive shift relearn on my trans. This cleared up the issue instantly.

When I got the vehicle home, I reflashed to the Roto 91 octane tune and kept all shift points stock, stock TM, etc (all stock). After that, the 6-3 shift boom remained gone (at least temporarily), but the 2-3 jerking was back. I flashed back to stock and everything felt great (e.g. no 2-3 hesitation/jerking into gear).

Either way, there is some issue with the TCM tune causing the adaptive shift software to go haywire and call for a shift that is out of the operating range of the transmission. I hope you guys will re-examine the shift pressures, etc because this is a potentially serious driveline issue for these vehicles. I would suggest (and request ) that you make an option where you can just tune the ECM (for RotoFab intakes), but leave the TCM software completely stock while we try to figure out the underlying tune issue.

Thanks.

I have an abrupt 2-3 up-shift when at WOT and low rpms in manual mode only (drive and sport mode are fine), no lurching.

We do not have adjustment for the line pressure with the 6 speed transmissions.
% of torque managment.
which you can adjust to a stock value.

We reduce torque management that will increase the feel of the force of the shift, but no pressure changes are made in the line pressure.

Along with the no changes to the downshifts made in the tuning.

Shift Torque Option, this feels a lot like the shift pressure we have currently but instead of Stock +2PSI, etc the option is percentage based between stock and the Superchips values. So this means there is (in order from lowest firmness to highest firmness) Stock Value, 25% Superchips, 50% Superchips, 75% Superchips, Superchips Value (which is 100%), 125% Superchips, 150% Superchips, and Max Value. The Max Value is very aggressive on some trucks/cars so we have added a warning screen that says: “Using Max Value removes all torque reduction during shifting. This setting is not covered by Superchips warranty and should be used cautiously.”

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Regardless, the shift quality becomes poor with the tune. According to what you're saying, when I keep TM and shift points at the "stock" setting, there should be no changes made to the shifting (no line pressure alterations), however, the shifts do indeed become forced and jerky (2-3).

Is it possible to make an option to leave the TCM tune the stock file? I want the SC RotoFab tune, but the stock TCM file. If the shifting issue won't be addressed in the SC TCM tune, I would rather just leave my TCM with the stock file to be honest.

Ron, I'm not sure if this sheds any light on your end, but worth noting about the 6L80 and the way the tunes can cause issue with the adaptive shift:

[quote = GRTG8]

I found this on GM Modern Muscle:"The 6L80 transmission utilizes a line pressure control system during upshifts to compensate for the normal wear of transmission components. As the apply components within the transmission wear or change over time, shift time (the time required to apply a clutch) increase or decreases. In order to compensate for these changes, the transmission control module (TCM) adjusts the pressure commands to the various PC solenoids, to maintain the originally calibrated shift timing. The automatic adjusting process is referred to as "adaptive learning" and it is used to ensure consistent shift feel plus increase transmission durability. The TCM monitors the A/T input speed sensor (ISS) and the A/T output speed sensor (OSS) during commanded shifts to determine if a shift is occurring too fast (harsh) or too slow (soft) and adjusts the corresponding pressure control (PC) solenoid signal to maintain the set shift feel.

The purpose of the adapt function is to automatically compensate the shift quality for the various vehicle shift control systems. The adapt function is a continuous process that will help to maintain optimal shift quality throughout the life of the vehicle." It is a neat tranny but very complex tuning. There are something like 400 peramiters and tables you can adjust and that is not everything, just what hptuners has uncovered. Some people say the adaptive shift times are what helps the tranny live with high hp.

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