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View Full Version : 4L60E Tranny Adaptive Learning 'DeProgramming'?



marsmann
01-16-2011, 08:10 PM
ok.

so i have an 02 NBS with a 4L60E. My problem (still) is that it shifts hard (clunk-like) from 1st to 2nd gear ONLY.

It is not mechanical or otherwise - fluid levels are what they should be, fluids have been flushed, shifter solenoids have been replaced, slip yoke has been regreased & packed (along with trying ridiculous rubber ball hacks, etc.), driveshaft is proper, I have programmed my shift points using my hypertech to no avail, etc., even played with line pressures recently but restored everything back to normal now.

My problem has to do with the adaptive learning / memory and table states in the transmission computer. I can clear them at will by slowing down while shifting into 1st or taking off in 1st and this resets the memory / shift points. After that, I can take off in standard Drive (4) and it shifts beautifully for the first few shifts in 1st to 2nd but eventually it goes back to the hard shift after it 'relearns'.

My guess is that even if I swap trannies I will have the same problem since the computer is responsible for the hard shifts. My truck shifts fine when the damn computer is not involved until it learns and injects its crappy 'adaptive' shifting - does anyone know of a way to disable adaptive learning permanently?? I dont need programming of the shift points as I tried that before - what I'd like to do if possible is kill adaptive learning - is there a way I can do it or do I have to take it to a tuner??? I'm hoping for a clever hack such as looping an ohm signal or something along those lines.

Or, better yet can I install an older 4L60E without the adaptive computer from an OBS - I suspect not since the computer will be expecting signals....

Grrr... any help appreciated.

transbuilderguy
01-18-2011, 04:50 PM
reset the computer and do the relarn at wot 2 times all the way to 3rd gear each time

NEUMANNZZ
01-19-2011, 03:01 PM
your gonna need to take it to a tuner that can disable it or buy tuning software.

Pauly
02-07-2011, 02:53 PM
All 4l60e's have adaptive shifting strategies. Resetting shift times to ZERO will remove "Adaptive Shifting strategies". I dont think this is your issue. Sounds to me that max line pressure is being commanded by the PCM. This can happen if the PCm determines that there has been slippage going on in the trans. In order to allow the trans to keep from frying the clutches, teh PCM commands max line pressure and pushes the clutches together as hard as it can. This results in a head against the back glass 01-2 upshift, even at barely any throttle.
If you get these hard shifts, pulling over and shutting the truck off, then restarting and driving on will temporarily restore normal shifting. Shortly though, the PCm after receiving slip signals, will again, recommand 100% line pressure, and the tire barking shifts will resurface.
This is a common issue, a competent trans shop should be able to easily diagnose this for you.

1st thing I would do, it to replace your stock PCM tune and see what happens.

Transbuilderguy would probably have some better reasons why the PCM woudl command 100% line pressure. Is a worn TCC apply bore/piston which causes high TCC slip a cause for PCM commanded 100% line pressure?

If a differnt rans was swapped in, I'm betting the issue would stop, as teh slippage wouldnt be present, therefore the PCM wouldnt command 100% line pressure to try and stop it. The trans swap isnt the proper fix though, replacing teh parts causing the problem is.

Just a theory, but has worked for me.

peace
PAuly

transbuilderguy
02-07-2011, 06:04 PM
All 4l60e's have adaptive shifting strategies. Resetting shift times to ZERO will remove "Adaptive Shifting strategies". I dont think this is your issue. Sounds to me that max line pressure is being commanded by the PCM. This can happen if the PCm determines that there has been slippage going on in the trans. In order to allow the trans to keep from frying the clutches, teh PCM commands max line pressure and pushes the clutches together as hard as it can. This results in a head against the back glass 01-2 upshift, even at barely any throttle.
If you get these hard shifts, pulling over and shutting the truck off, then restarting and driving on will temporarily restore normal shifting. Shortly though, the PCm after receiving slip signals, will again, recommand 100% line pressure, and the tire barking shifts will resurface.
This is a common issue, a competent trans shop should be able to easily diagnose this for you.

1st thing I would do, it to replace your stock PCM tune and see what happens.

Transbuilderguy would probably have some better reasons why the PCM woudl command 100% line pressure. Is a worn TCC apply bore/piston which causes high TCC slip a cause for PCM commanded 100% line pressure?

If a differnt rans was swapped in, I'm betting the issue would stop, as teh slippage wouldnt be present, therefore the PCM wouldnt command 100% line pressure to try and stop it. The trans swap isnt the proper fix though, replacing teh parts causing the problem is.

Just a theory, but has worked for me.

peace
PAuly
yes a converter slip will command max line pressure there are few driveabolity isses that will do it also MAF, map and some misfires.