random delayed 2nd to 3rd shift

Jeep GC 2016 srt8
zf8spd

I have a random delayed 2nd to 3rd shift , generally after coming to rest say at a light .
Its more evident when cold but will still arise randomly when at normal running temps ,

where it would normally change at about 1500 eng rpm under 20 % throttle or less on the odd occasion it will run as high as 2700 rpm, unless I reduce acc and then it will shift

I have been chasing this for months tried various shift schedule changes and Tcc lock up variations which have improved various areas but the underling random behaviour 2/3 remains

Any thoughts would be appreciated !

Post ur trans tune...it will be in there somewhere.
Flat road or on an incline?

HemiTuna will spot it if there's something off. He's helped me learn a lot about the ZF8

Do you have anything on the RAM EcoDiesel 8HP70?

Never messed with one. These transmissions are pretty complex though. Seems like about every time you make it shift faster you're back to readjusting everything else to keep it from slipping or shifting too hard.

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Originally Posted by ridenrunwv

Never messed with one. These transmissions are pretty complex though. Seems like about every time you make it shift faster you're back to readjusting everything else to keep it from slipping or shifting too hard.

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Make sure you are using the latest beta.

This trans has a ton of settings that can't be seen in older versions.

Amazing trans when tuned well!

Attachment 84449

Hi ,HT

Thank you for your reply
I hope the tune appears above , Have not done this before and Im a little unsure of whats req
the odd behaviour 2/3 shift happens on flat road and to a lesser extent effects 3/4 as well
I do have a tcm logging problem HP is looking at , Currently I cant identify what map number its using or tcm map nos ,,, I used to be able to but there is some break blocking the data stream..

What trans mode when it does this??

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Originally Posted by Hemituna

What trans mode when it does this??

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Normal mode , I will have a look see if I have a good log that shows it
Nige

I'd hazard a guess it is the TCC.
Your 2/3 shift at 20% and less is rather close to the converter lock up speed.
Try lowering the lock up speeds and/or also the converter slip % especially if you have more tq than stock.

Ok
Yes does have more tq ,, procharger F1a 12+ psi max


However when it does delay it does not feel like its slipping and is above lock up by quite a bit ,,That has been an approach Ive been exploring as you can see,, but perhaps not far enough ?,The car is much better to drive with my current Tcc revisions ,

If HP can fix my logging problems perhaps I can get some useful data covering the problem event and when its OK,,
Q
Converter slip % , That's the new set 0f 70 odd tables isn't it ?

Thanks heaps

Q
Converter slip % , That's the new set 0f 70 odd tables isn't it ?

Sure is.

Quote:

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Originally Posted by Nigel Pitsch

Jeep GC 2016 srt8
zf8spd

I have a random delayed 2nd to 3rd shift , generally after coming to rest say at a light .
Its more evident when cold but will still arise randomly when at normal running temps ,

where it would normally change at about 1500 eng rpm under 20 % throttle or less on the odd occasion it will run as high as 2700 rpm, unless I reduce acc and then it will shift

I have been chasing this for months tried various shift schedule changes and Tcc lock up variations which have improved various areas but the underling random behaviour 2/3 remains

Any thoughts would be appreciated !

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Look at shift scheduling, table 5 under aggression 0. The problem is that your 2>3 and 4>3 are 425 at low throttle. Raise the 4>3 downshift rpms so the transmission isn't trying to shift up, down, down, up....basically. Attachment 85291

Quote:

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Originally Posted by Spooby

Look at shift scheduling, table 5 under aggression 0. The problem is that your 2>3 and 4>3 are 425 at low throttle. Raise the 4>3 downshift rpms so the transmission isn't trying to shift up, down, down, up....basically. Attachment 85291

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Sorry I have been busy so bit slow to reply, !!

Thanks for looking !! I will have a look at that ,
You will probably have seen I have overwritten all the aggression 0 and 1 maps..

What gets me is 70 % of the time its very nice and I like the feel of it,, the car has quite a bit of TQ and does not need to rev to get moving ,, but ill try your suggestion see if behaviour is improved
Thanks
N

PS it does it 2>3 upshift mostly and these shift numbers are not close