2009 STS-V 6L80E Clunky 2-1 Downshift

[northstarV]

Hello everyone,

My 2009 STS-V has a clunky 2-1 downshift and sometimes a 3-2 as well. When coming to a quick stop, it downshifts at 6MPH and feels like it pulls the engine down with it, makes the shift and idles back to normal. I changed the MPH downshift table to 3MPH but it didn't smooth it out. The car has been tuned to 420WHP/460WTQ not by me, but has always done it stock. I have the current tune file attahced. I am very new to tuning, and if it is a relatively easy thing to change, I'll give it a shot. I'm looking to see if I can smooth it out. Thanks in advance!




2009 Cadillac STS-V Tune.hpt

[Alvin]

You can try disabling CT Downshift in the torque management section. Some people say that effects the TUTD stuff. I've never seen that personally.

Beyond that you'll need to dial in the downshifts so that it isn't dragging the engine down as you come to a stop.

[TransGo Robert]

Sounds like your lock-up is not able to releasing, send a log of the data so that I can tell for sure if that's what is happening or not.

[STAGEUP]

Try this and report back..

[northstarV]

Thanks everyone for the replies. I'll upload that tune file in a few hours and report back. If it doesn't fix it, I'll disable CT Downshift in TM and see if the Rev-matching is still there.

[northstarV]

I loaded that tune on, it seemed to help a little bit but it was still there. I swapped back to my original 6MPH 2-1 downshift and turned off CT Downshift in TM. That seems really smooth but the rev-match is gone with the TUTD. I read on another thread that you could change the "Shift Inertia Factor Profile CT Downshift". Mine are currently all set to 9 between 0-1000RPM, would reducing these down to like 5 or 4 help with a smoother downshift?

[hjtrbo]

Worth a try. Just trying stuff is how most of us have worked shit out. Never played with that table myself. I'd love to hear your thoughts on how it goes.

[northstarV]

I re-enabled CT Downshift in TM, and reduced the coefficients in the "Shift Inertia Factor Profile CT Downshift" table. It seemed to help a lot. All downshifts seem really smooth especially when the trans is hot. Thanks everyone for your replies.

[hjtrbo]

Would you mind posting up your new tune. It could be really helpful to others. Cheers

[northstarV]

Of course!

2009 Cadillac STS-V Updated TM.hpt