New A6 Transmission parameters walkthrough

[bluessv]

Yeah well all I can say is I've been driving around now for nearly 2 days with the "Max Adapt Volume" table set at 200 across the board and the difference is black and white. My trans has never shifted like it has in the last few days!

If the trans is using the same clutch for different shifts like mentioned above then I'm even more confident that I'm not asking too much of the trans. If it's using the same clutch for the 4-5 shift and that was set at 200 then there should be nothing wrong with setting the 2-3 shift at 200 too??

So far so good anyway. I'm also playing around with the torque management when the trans is cold. I find that the pause hesitation on the downshifts (when the trans commands zero torque because the box hasn't completed the downshifts) as part of the Torque Management isn't commanding for long enough. As a result the trans finishes the "Zero Torque" command too quickly and the box still hasn't finished the downshifts. ONLY HAPPENS WHEN TRANS IS COLD. NOT AN ISSUE AT ALL WHEN TRANS IS WARM TO OPERATING TEMPERATURE.

I'll let you know how I go with that if there's anyone interested who appears to be having the same issues.

[kenny c]

Yeah well all I can say is I've been driving around now for nearly 2 days with the "Max Adapt Volume" table set at 200 across the board and the difference is black and white. My trans has never shifted like it has in the last few days!

If the trans is using the same clutch for different shifts like mentioned above then I'm even more confident that I'm not asking too much of the trans. If it's using the same clutch for the 4-5 shift and that was set at 200 then there should be nothing wrong with setting the 2-3 shift at 200 too??

So far so good anyway. I'm also playing around with the torque management when the trans is cold. I find that the pause hesitation on the downshifts (when the trans commands zero torque because the box hasn't completed the downshifts) as part of the Torque Management isn't commanding for long enough. As a result the trans finishes the "Zero Torque" command too quickly and the box still hasn't finished the downshifts. ONLY HAPPENS WHEN TRANS IS COLD. NOT AN ISSUE AT ALL WHEN TRANS IS WARM TO OPERATING TEMPERATURE.

I'll let you know how I go with that if there's anyone interested who appears to be having the same issues.

You might try changing the shift torque factor/cold multiplier table on the TM tab in the temp ranges that you are having issues with.

I also noticed that my TCC table is set to only apply the TCC in 3rd gear and above and never unlock it when coming back down to 2nd, only in first. What's the purpose in that? Couldn't I resolve some drivability issues and increase performance by always having it locked in 1st - 3rd and then let it unlock while cruising in 4th for better MPG...or am I missing something here?

Here's my stock TCC table.

[n77nxc]

Yeah well all I can say is I've been driving around now for nearly 2 days with the "Max Adapt Volume" table set at 200 across the board and the difference is black and white. My trans has never shifted like it has in the last few days!

If the trans is using the same clutch for different shifts like mentioned above then I'm even more confident that I'm not asking too much of the trans. If it's using the same clutch for the 4-5 shift and that was set at 200 then there should be nothing wrong with setting the 2-3 shift at 200 too??

So far so good anyway. I'm also playing around with the torque management when the trans is cold. I find that the pause hesitation on the downshifts (when the trans commands zero torque because the box hasn't completed the downshifts) as part of the Torque Management isn't commanding for long enough. As a result the trans finishes the "Zero Torque" command too quickly and the box still hasn't finished the downshifts. ONLY HAPPENS WHEN TRANS IS COLD. NOT AN ISSUE AT ALL WHEN TRANS IS WARM TO OPERATING TEMPERATURE.

I'll let you know how I go with that if there's anyone interested who appears to be having the same issues.

I can't wait to hit the track and see what kind of improvements I see there. The car was running strong before, but it definitely seems like I picked something up between shifts. I'll post the results after my next track day.

[LSX378]

You might try changing the shift torque factor/cold multiplier table on the TM tab in the temp ranges that you are having issues with.

I also noticed that my TCC table is set to only apply the TCC in 3rd gear and above and never unlock it when coming back down to 2nd, only in first. What's the purpose in that? Couldn't I resolve some drivability issues and increase performance by always having it locked in 1st - 3rd and then let it unlock while cruising in 4th for better MPG...or am I missing something here?

Here's my stock TCC table.

It seems GM rarely locks in 1 & not often in 2. Maybe it is a torque capacity/impulse thing or they dont feel that the trans is typically in gear long enough to warrant it in terms of gaining any advantage.

On deccel, your TCC probably unlocks in 3rd. You would need to log to check. Generally at zero pedal the TCC has unlocked. If it changes to 2nd from 3rd, it most likely also unlocks. One of the objectives of converter locking is increased mpg. So you wouldn't want it unlocked to try and gain mpg.

[kenny c]

It seems GM rarely locks in 1 & not often in 2. Maybe it is a torque capacity/impulse thing or they dont feel that the trans is typically in gear long enough to warrant it in terms of gaining any advantage.

On deccel, your TCC probably unlocks in 3rd. You would need to log to check. Generally at zero pedal the TCC has unlocked. If it changes to 2nd from 3rd, it most likely also unlocks. One of the objectives of converter locking is increased mpg. So you wouldn't want it unlocked to try and gain mpg.

Thanks...wasn't sure if I had that backwards or not.

[bluessv]

Hey does anyone know how the Oncoming Pressure Preset tables work? Has anyone figured out what the Axis means (0,1,2)? And how do the clutches work on a shift. Does the Oncoming clutch for a specific shift engage and then the Offgoing clutch... or the other way?

[LSX378]

Hey does anyone know how the Oncoming Pressure Preset tables work? Has anyone figured out what the Axis means (0,1,2)? And how do the clutches work on a shift. Does the Oncoming clutch for a specific shift engage and then the Offgoing clutch... or the other way?

Good question on the 0,1,2 axis. It may be 3 phases of clutch apply, or maybe relates to Low, Med, High in Discrete Shift Torque.

The offgoing clutch releases first, then oncoming applies. All in 100-500ms. Otherway round it is in 2 gears at the same time: lockup, dead parts, smoke.

[bluessv]

So if I was thinking of increasing the clutch pressure on the 2-3 shift then I'd look at increasing the oncoming clutch as this is what grabs the 3rd gear??

[bluessv]

So does anyone out there know any more about the Oncoming Pressure Preset tables, such as what the Axis mean (0,1,2)?? Anyone??

[LSX378]

So does anyone out there know any more about the Oncoming Pressure Preset tables, such as what the Axis mean (0,1,2)?? Anyone??

I would almost bet it is 3 phases or zones of clutch operation. i.e. low pressure to start clutch fill, then medium pressure, then higher pressure to complete clutch application.

Nothing unusual in the operation of hydraulic systems where too much shock needs to be avoided.

Am sure Chris@HPT could confirm (or not) if he gets a chance.

[bluessv]

"Too much shock needs to be avoided"...

Are you referring to too much pressure?? Didn't exactly follow

[LSX378]

"Too much shock needs to be avoided"...

Are you referring to too much pressure?? Didn't exactly follow

Pressure ramped up in 3 stages vs just switching full pressure on.

The clutch pistons also have piston ring style seals, which have a breakaway friction, so the low pressure would also have a function in kicking off the clutch piston travel and once it starts moving, ramp pressure towards full.

A lot easier to control the rate of clutch application with 3 phases.

Picture it like this, low pressure to commence the clutch piston moving, medium pressure to take it towards clutch engage until the friction has commenced, and then full pressure to clamp it 100% engaged and squeeze all the oil out from between the clutch fixed and moving plates. Done.

Sorry if this is difficult to grasp without diagrams. When you work in a GM trans plant, it kinda grows on you.

[Chris@HPTuners]

i believe the 0,1,2 values correspond to low, med & high torque regions.

[bluessv]

Thanks for that, it makes perfect sense. As already stated in previous posts, I've had ongoing issues with my trans flaring on the 2-3 change....CONSTANTLY!!

I have made several changes to my tune over the last few weeks. The changes involve tweaking Discrete Shift Torque however keeping it enabled. I've pretty much just changed the "Low" table to reflect 160 torque on the 2-3 change instead of Zero torque. I'm hoping that this will enable the trans to learn a stable torque band and therefore learn a stable shift. However, making that stable torque band on low throttle at least something rather than Zero. I'm sure this helps with the flare as I think it ensures the trans uses a mid range "Base Pressure" rather than the lowest "Base Pressure".

I've also increased the "Oncoming Volume Preset" from 21.500 to 30.000. The theory behind this is to ensure there is sufficient volume on the Clutch Adapt just in case GM is running them a little lean. I've also increased the "Max Adapt Volume" up to 200. The 2-3 change was set extremely low compared to all other shift changes (was set at 40 while the others were set to 200). Again, the theory behind this was to ensure the trans has sufficient backup volume to compensate for any potential flaring that I'm having.

I also noticed that the stock tune on the Commodore SS in Australia runs slightly lower "Base Shift Pressure Upshift" tables on the 2-3 shift compared to it's exact equivilant (Pontiac G8). It's not much but in the most common ranges there is about a 100-150kpa difference. As a result I've changed my "Base Shift Pressure Upshift" table for the 2-3 shift to reflect those of the Pontiac.

Finally, I took the leap of faith and had a play with the "Oncoming Pressure Preset" tables for the 2-3 shift, both normal and special. I increased the pressures on all three (3) stages by 30kpa. This makes the pressure readings go from 170,300,430 to 200,330,460. These changes still keep the same increase level as set in the stock tune but just starting, maintaining and finishing at a slightly higher pressure. The theory behind this is that my specific trans seems to have an issue with pressure from the factory and is very good at improving beyond recognition when the pressures are increased slightly. By increasing the "Oncoming Clutch" pressure I hoped that this would allow the clutch to grab the next gear easier and therefore have my trans actually change like it should instead of constantly having this flare and drawn out change all the time.

So far the results are very promising!! I took the car for a quick spin and there was no flare. Gone! Surprise, surprise. As a package I think I'm getting close to elliminating the flare by increasing the clutch pressures and the overall base pressures. While slightly tampering with the Discrete Shift Torque to allow the trans to always shift with some level of torque even at minor throttle.

I will give it a few days to allow the trans to "learn" and start making some calculated guesses of it's own. Once it has done some km's (miles) I'll get back on and give some feedback as to how this package has affected the trans changes.

By the way, did I mention my head hurts!!

[LSX378]

i believe the 0,1,2 values correspond to low, med & high torque regions.

Ok thanks. So they are the 3 adapt "regions"?

If that's the case, should the axis units be Torque/Nm vs currently listed Pressure/kpa? For example pressure at 100kpa is a little low for anything trans related.

[Chris@HPTuners]

they are pressure values in kPa.

[LSX378]

they are pressure values in kPa.

Thanks for the clarification. I stand corrected.

[GETUSUMM]

Can anyone post up a before and after tune? I would love to see the differences. Thanks

[seevi]

On the A6 walkthru above, has this been updated. When I go to look at the transmission report on my car, it doesn't look like that.

[TonyB4]

On the A6 walkthru above, has this been updated. When I go to look at the transmission report on my car, it doesn't look like that.

You need to go back to the main page of HPT`s website and download the 2.22. Its on the home page,click on GO TO CUSTOMER CENTER. If you need any help just pm me.