Adaptive Learning

[EVI]

Could someone please explain what adaptive learning learns and what it adjust.
Thanks

[joecar]

Generally speaking:

It learns the shift "feel" and time, and trims it by controlling pressure and rate of pressure (ramp up/down).

There's more to it than that, but that is as much as I know.

[EVI]

Thanks for the reply but what is the target? Does it try to adjust to a pre-programmed target, like AFR and if so can I change the target? Should I disable adaptive learn for up-shifts if I want full time firmer up-shifts?

[joecar]

The targets are typically these:
- shift time tables,
- shift pressure tables;

No, you don't necessarily disable adaptive learn for firmer shift (the shift will be hard rather than firm)... instead you modify the targets...

WARNING:

The 6L80/6L90/6T75 transmissions operate on a clutch-to-clutch basis...
i.e. the TCM controls the timing between the releasing component (i.e. for the gear it's coming from) and the applying component (i.e. for gear it's going into)...
if this release/apply timing gets messed up the transmission will suffer internal damage.

You will need to get more guidance on how to do this safely from someone who has gotten good results (I haven't had the chance to play with these).

[EVI]

OK, I don't mean to beat a dead horse, I just want to thoroughly understand so I can be a better tuner. That being said, I still don't really understand why we need adaptive learn. If the target for shift time is say .500 sec then why not just command .500 sec like on the 4l60e. There are no variables like baro or air temp or humidity like with AFR. It seems to me that if you don't disable adaptive learn, then whether your tune is for a hard shifts or soft shifts you would end up with the same feel as you started with after adaptive learn gets the values back to whatever it's target is. Don't give up on me now Joecar.

[CV8IIM6]

I’m certainly no expert but here’s my understanding:

If you command a shift time of say 0.325 seconds and a base line pressure of say 1250Nm, when the TCM performs that shift it may only achieve a shift time of .600
This could be because of individual clutch characteristics, line pressure may not be high enough or perhaps torque reduction is not right etc. etc........

If adaptive shift is OFF the TCM won’t know and/or care that it’s not achieving the desired shift time and will continue getting it wrong.

With adaptive shift ON the TCM monitors “actual shift time” and compares it to “desired shift time”
Then if they don’t match the TCM will take steps (like adjusting line pressures) to correct the discrepancy.

I have found it generally takes about five shifts in each cell to learn the tune, this can take several drive cycles or up to 2 weeks.

I think the 4L60E has to learn to some extent too but someone who thoroughly understands the internal workings of both transmissions may be able to shed some light on why it seems the 6L80E has to learn so much more.

[oztracktuning]

Turn off adaptive learning and face high risk of the numbers not being anywhere near right and that will be costly.
These TCMs are able to do incredible adaptation when the calibrations are right. They can be improved in their shift feel incredibly and last. But turning off adapts is a dead end road.

[Patrick G]

Any idea why the 2-3 shift max adapt volume (D9264) is 40 while the rest of the shifts are 200? Would this narrowed learning volume explain why some of us have light load 2-3 shift flares, but solid heavy load 2-3 shifts? Would opening up the adaptive volume to 200 help the 2-3 shifts?

[joecar]

Any idea why the 2-3 shift max adapt volume (D9264) is 40 while the rest of the shifts are 200? Would this narrowed learning volume explain why some of us have light load 2-3 shift flares, but solid heavy load 2-3 shifts? Would opening up the adaptive volume to 200 help the 2-3 shifts?

That is very odd...

I wonder if there are any T43 calibrations having D9264 set to other than 40 cm³...?

[joecar]

OK, I don't mean to beat a dead horse, I just want to thoroughly understand so I can be a better tuner. That being said, I still don't really understand why we need adaptive learn. If the target for shift time is say .500 sec then why not just command .500 sec like on the 4l60e. There are no variables like baro or air temp or humidity like with AFR. It seems to me that if you don't disable adaptive learn, then whether your tune is for a hard shifts or soft shifts you would end up with the same feel as you started with after adaptive learn gets the values back to whatever it's target is. Don't give up on me now Joecar.

If shift learning is turned off, the trans will just command each shift using line pressure from the shift pressure tables (shift pressure vs engine torque) without regards to timing or ramping...

In the 6L80 this will not be good (release/apply of components is performed by multiple hydraulic circuits, so release/apply timing is a function of the TCM calibration/algorithm)... if the release/apply components are "stepped" off/on (respectively) at their natural physical speed (which is fast), then component binding would occur (the releasing component takes longer to release than the apply component takes to apply... in effect this would give you a trans brake effect for a brief moment), this will quickly and efficiently damage internal components.

In the 4L60E/4L80E this will be fine (release/apply of components is performed by a single hydraulic circuit, so release/apply timing is a function of the hydraulic/mechanical physics (i.e. the volume of the accumulators, the size of holes in the VB separator plate, the servo piston sizes))... there will be no release/apply component binding... if the shift pressure tables have sensible pressure vs torque values, each upshift can be very quick/hard... the shift pressure tables by themselves command line pressure with no timing trimming, this does not constitute learning (you can see this when you set the shift time tables to zero or when you disable the MAF for example).

Adaptive learn makes an attempt to converge to the values in the shift time and pressure tables... you adjust these to get firmer shifts, but you have to know how much adjustment you can get away with...

And then there are other tables to consider such as max adapt volume as PatrickG pointed out.

Why not just command 0.500 s on a shift with no learned timing feedback/trimming...? Commanding 0.500 s is quite slow and may actually be ok... but commanding 0.100 s is fairly quick and may not be ok (miss-timing of release/apply components)... on the 6L80 shift learning is everything.

I'm not giving up on you (I don't have one of these to play with)... I am seriously saying you have to be careful with this.