New A6 Transmission parameters walkthrough

[RWTD]

Also, I'm guessing that if you leave the speed at 27MPH and bump the RPM up to 3000 or drop it down to something low like 2000 you'll still find that it shifts right around 5600 every time as if you hadn't changed the RPM at all.

Makes you want to pull your GD hair out, doesn't it?

[LSX378]

"You will never convince racing people that it is better to let the PCM cut torque to get a faster shift that isn't as hard on parts "

I think we definately have enough params uncovered now for people to make the A6 shift well. The only remaining thing i have is to find out what makes the TUTD react slowly and if it can be changed.

That seems to be changing. The discovery that disabling TM messes up shifting has some profile now..... .

Any feedback yet on the TUTD "inbuilt" delay?

My own guess is that this is additional processing delay as there is less predictability around shift point, i.e. in auto the trans "knows" it will be shifting and can cater for that, with TUTD its all a surprise. Though there must be some factoring hidden there somewhere to tailor it.

Thx.

[johnh]

As I described above I have all the TQM on, but with the STF params can make the shifts break the wheels loose at higher RPM/torque values but keep the shifts soft during cruising.

Besides any hard shifting is always gonna be harder on the hard parts...tqm or not. I figure let TQM save wear and tear and only be hard when I want it.

I haven't played with TUTD settings at all.

[BSmith]

Any feedback yet on the TUTD "inbuilt" delay?

My own guess is that this is additional processing delay as there is less predictability around shift point, i.e. in auto the trans "knows" it will be shifting and can cater for that, with TUTD its all a surprise. Though there must be some factoring hidden there somewhere to tailor it.

Thx.

There's another thread that mentioned the BCM.

Readers digest version... you can use corvette controls for tap up and tap down function. This will be faster than through the bcm also.

Link

I just caught the last part of this thread, so sorry if it's been discussed before.

[LSX378]

As I described above I have all the TQM on, but with the STF params can make the shifts break the wheels loose at higher RPM/torque values but keep the shifts soft during cruising.

Besides any hard shifting is always gonna be harder on the hard parts...tqm or not. I figure let TQM save wear and tear and only be hard when I want it.

I haven't played with TUTD settings at all.

Similar outcome here, though just by changing shift timing. in "Normal" modde shifts could be described as instantaneous at part throttle, take around 100ms and they are smooth and sweet. TUTD very quick at low rpm/high torque. Now working on quicker shifts at higher torque/higher rpm values. I guess STF is the way there.

[LSX378]

There's another thread that mentioned the BCM.


Link

I just caught the last part of this thread, so sorry if it's been discussed before.

Yes the BCM/CAN based TUTD adds potential latency depending on CAN traffic, though it is still the trans calibration that has the major effect. It would be interesting to know if latency is the real reason that GM chose the direct connect TUTD mode for the Corvette, or it is purely a legacy thing as the Corvette was an early example of the A6 and GM has simply gone for less wire, and a BCM that rules the world since then.

[ktoonsez]

Bill@HPTuner:
I was wondering if there are those same newer TM parameters that are in the beta for downshifts life 2-1, 3-2?

[bluessv]

Can someone assist me with getting my head around shift pressures. I want to leave the Desired Shift Time tables alone at the moment however I have a flare issue in the 2nd to 3rd change. I believe it's mainly associated with the, what appears to be, quite low pressures set in the Base Shift Pressure Upshift tables (X,Y and Z). If I wish to increase the shift pressure during a specific shift do I only need to change the Base Shift Pressure Upshift tables or are there other tables I also need to pay attention to. Such tables may include the Max Line Pressure table or possibly the Oncoming/Offgoing Pressure Preset tables. I only through those one up as a suggestion as I have no idea what they do.

My other quick question is what is the difference between the Shift Pattern tables. I've viewed various tunes out there and they all seem to have different combinations of what they nominate as the Pattern A and Pattern B (normal/patt 1/cruise/performance). What does this table do and why are there so many different combinations yet the tuning software states they don't recommend changing them??

[LSX378]

Can someone assist me with getting my head around shift pressures. I want to leave the Desired Shift Time tables alone at the moment however I have a flare issue in the 2nd to 3rd change. I believe it's mainly associated with the, what appears to be, quite low pressures set in the Base Shift Pressure Upshift tables (X,Y and Z). If I wish to increase the shift pressure during a specific shift do I only need to change the Base Shift Pressure Upshift tables or are there other tables I also need to pay attention to. Such tables may include the Max Line Pressure table or possibly the Oncoming/Offgoing Pressure Preset tables. I only through those one up as a suggestion as I have no idea what they do.

My other quick question is what is the difference between the Shift Pattern tables. I've viewed various tunes out there and they all seem to have different combinations of what they nominate as the Pattern A and Pattern B (normal/patt 1/cruise/performance). What does this table do and why are there so many different combinations yet the tuning software states they don't recommend changing them??

Maybe you are already doing it, but certainly worth doing some logging prior to making any changes. Look at shift times, torque levels, torque managment retard, mph etc etc and find out exactly where your flare is occurring.

Any reason why you want to look at pressures vs shift times?

[bluessv]

I'm happy with the shift speed but get this annoying flare on the 2-3 change every so often. I found that I could nearly elliminate it by uping the pressures on that shift. I've played around with the shift times before and found that I get a firmer, harsher shift. I know this is normal when decreasing the shift time but it's not what I'm after. I was more curious as to whether just changing the Base Shift Pressure tables were the only tables linked to the shift pressures on specific shifts??

I'm only new to this tuning thing too so all the other stuff you mention about torque and logging is something I don't understand. How do you do a log and then interpret the log to identify the flare??

[bluessv]

And also.... How much can you put up the pressures on any specific shift. I've noticed that different shifts have different degrees of pressure. For example, the normal running pressure on the 2-3 shift (part throttle) was only about 90. With F/T increasing up to 145. I've increased the Base Shift Pressure to 160 across the board and it seems to have rectified the flare issue. But now I'm wondering.... How far can you increase it by? I haven't increased it to beyond other shifts though

[LSX378]

I'm happy with the shift speed but get this annoying flare on the 2-3 change every so often. I found that I could nearly elliminate it by uping the pressures on that shift. I've played around with the shift times before and found that I get a firmer, harsher shift. I know this is normal when decreasing the shift time but it's not what I'm after. I was more curious as to whether just changing the Base Shift Pressure tables were the only tables linked to the shift pressures on specific shifts??

I'm only new to this tuning thing too so all the other stuff you mention about torque and logging is something I don't understand. How do you do a log and then interpret the log to identify the flare??

Logging is your friend! It will be well worth your time to learn how to use it in HPT.

If you look here:

http://www.hptuners.com/forum/showthread.php?t=5058

There is a section on scanning (covers logging).

The A6 manages torque along with the ECM to shift smoothly. Engine torque affects shift behavior. Logging parameters such as gear, shift time, torque, pressures, TM spark retard will give you hard information on what the trans is doing vs just seat of pants.

When was your trans flaring? very light throttle, half, full throttle? Straight line? Corner? With PAS - Performance Shifting, some situations will create what some may term a flare, when the trans is simply making an educated guess that may not be correct at times.

On pressures, while shift time and shift profile in relation to torque/speed is probably more relevant, max pressure is 2000kpa IIRC. Looks like your pressure may be in PSI. 145 being ~1000kpa. Not many outside of GM know what safely works. Just because max pressure is 2000kpa though, doesn;t mean the trans will operate properly or safely up there...

[bluessv]

Thanks for that info on logging... Sounds like it's an excellent tool for diagnosis purposes.

The flare I'm referring to is a common complaint for these A6 boxes; at least in Australia anyway. It is when the trans takes longer than normal in the 2-3 change and during that longer delay the rev's slightly increase by about 300-400 rpm. It's almost like when you change gear in a manual and hold on the clutch slightly too long. Happens all the time in many different circumstances and I'm pretty sure it's not the PAS.

GM will tell you it air getting in behind the clutch packs and the A6 bleeds the air during the 2-3 change and will do it every 2-3 shift until the air has been cled out. According to them this may take the trans oil to be over 40 degree celcius before it can work the air out. BUT I DON'T BUY THAT!!

If you look carefully over the Base Shift Pressure Upshift table (X,Y and Z) they all have pretty good pressures during mid to F/T changes. Except the 2-3 shift only has low to moderate pressure unless you're F/T. My humble summary was that the trans was running too low a pressure and the flare I was feeling was in fact the shift make every attempt to shift according to the set parameters but not having enough pressure to do so. But I'm no expert.

So I went in and slowly increased the pressures and tested as I went along and found that the flare problem was almost non existent after bumping the pressure up to about 140 or so. My last change was to increase the pressure across the board to 160 and so far through testing the flare has completely disappeared!! Surprise, surprise GM!!

It's funny too cause the 3-4 shift has the same Desired Shift Time (0.3496) as the 2-3 change however runs much higher pressures across the board then the 2-3 shift. Up to 180+ when F/T on the 3-4 shift. And you guessed it....never felt a flare on the 3-4 shift EVER.

I'm certainly no expert, no mech background but I'm convinced I'm onto something with GM running way too low pressures on the 2-3 shift which is causing a huge amount of complaints in Aus with flare on the 2-3 shift. Would be interesting to hear from anyone in the USA to see if they are having similar complaints as I can only notice that the USA are also running low pressures however sometime have quicker Desired Shift Times on the 2-3 shift (0.2900).

[johnh]

It is when the trans takes longer than normal in the 2-3 change and during that longer delay the rev's slightly increase by about 300-400 rpm. It's almost like when you change gear in a manual and hold on the clutch slightly too long.

I've seen this too...you said you fixed it? Can you post your file?

[LSX378]

Thanks for that info on logging... Sounds like it's an excellent tool for diagnosis purposes.

The flare I'm referring to is a common complaint for these A6 boxes; at least in Australia anyway. It is when the trans takes longer than normal in the 2-3 change and during that longer delay the rev's slightly increase by about 300-400 rpm. It's almost like when you change gear in a manual and hold on the clutch slightly too long. Happens all the time in many different circumstances and I'm pretty sure it's not the PAS.

GM will tell you it air getting in behind the clutch packs and the A6 bleeds the air during the 2-3 change and will do it every 2-3 shift until the air has been cled out. According to them this may take the trans oil to be over 40 degree celcius before it can work the air out. BUT I DON'T BUY THAT!!

If you look carefully over the Base Shift Pressure Upshift table (X,Y and Z) they all have pretty good pressures during mid to F/T changes. Except the 2-3 shift only has low to moderate pressure unless you're F/T. My humble summary was that the trans was running too low a pressure and the flare I was feeling was in fact the shift make every attempt to shift according to the set parameters but not having enough pressure to do so. But I'm no expert.

So I went in and slowly increased the pressures and tested as I went along and found that the flare problem was almost non existent after bumping the pressure up to about 140 or so. My last change was to increase the pressure across the board to 160 and so far through testing the flare has completely disappeared!! Surprise, surprise GM!!

It's funny too cause the 3-4 shift has the same Desired Shift Time (0.3496) as the 2-3 change however runs much higher pressures across the board then the 2-3 shift. Up to 180+ when F/T on the 3-4 shift. And you guessed it....never felt a flare on the 3-4 shift EVER.

I'm certainly no expert, no mech background but I'm convinced I'm onto something with GM running way too low pressures on the 2-3 shift which is causing a huge amount of complaints in Aus with flare on the 2-3 shift. Would be interesting to hear from anyone in the USA to see if they are having similar complaints as I can only notice that the USA are also running low pressures however sometime have quicker Desired Shift Times on the 2-3 shift (0.2900).

After "spirited" acceleration in 1st and 2nd, there is usually something that appears to be a flare on the 2-3 if you back off slightly before the change.

What is the OS number in your trans. 24239353?

The G8 in the US has had at least 7 revisions since intro so the Oz cars probably have too.

Pressures up to 200psi are not uncommon at normal operating temps, but there is more to it than just the pressure. Just need to be cautious on the increments. The logging will tell you what is happening during the shift. i.e. is TM working as it should. What the actual shift time is. 0.5s or 3s....

It would be easier if you posted an image of the cal you area are looking at.

Yeah I dont know if I buy the clutch purge cause, but it is an official reason .

Considering how good we can get these trans shifting in the aftermarket, it is surprising that with GM's money (well, when they had more money) they could not get this area better than they did. Then again though, its all about budgets. If the budget says you finish this cal at 5pm on X date with no overtime allowed. There it stops and you go home .

Sad, but reality.

If more pressure works for you. Excellent results!

[MNR-0]

Shift flare caused by bleeding line pressures sounds like a crock of sh!t to me. Does it do it in every shift mode? Like auto, auto-manual and full manual?

[LSX378]

Shift flare caused by bleeding line pressures sounds like a crock of sh!t to me. Does it do it in every shift mode? Like auto, auto-manual and full manual?

Full to overflowing.....

Seriously the TSB lists this as normal, but only if it occurs once per cold start.

I guess normal means "not serious: no money to fix". Of course, the fact that other cals dont do it.....

[bluessv]

As I'm still getting my head around logging (never tried it before) I'll go out tonight and do some driving/logging. When I get back I'll post my log so someone out there might be able to help interpret it. I'll also post my tune for you to see. There's nothing really interesting about it except that I've increased the pressures on the 2-3 shift on all shift patterns (X,Y and Z).

I do get 1, maybe 2, flares on the 2-3 shift after about 5 minutes of driving but after that it gone. I have been one of the unfortunate ones that had an A6 which flared EVERY 2-3 shift for the first 45 min of driving. GM told me it was normal until the lines bleed but no matter how hot the box got it would still flare.

The most interesting thing is that by increasing the pressures on the 2-3 shift the problem all but goes. I can however make the flare return by simply adjusting the pressures back to stock.

Give me some time and I'll get my tune/log and OS number on here tonight.

[MNR-0]

Has anyone managed to remove the TQM (spark retard during shift) totally and at WOT in their A6 yet for all 3 upshifts? If so, please post log and explain how...

Cause i'm stuffed if I can find a way

[bluessv]

Well I've gone for a drive and successfully logged the car with the stock tune running and with my tune running. Everything went fine until I tried to save it to my computer. I LOST THEM AND I'M PISSED!

All I know is that when I drive around with the stock tune the A6 wants to flare and drag out the 2-3 shift all the time. Nearly every 2-3 shift except for when the car is dead cold. In that case, the A6 won't start flaring until about 5 min into the drive and then will continue for ever and a day.

Alternatively, when I run my tune (with the higher Base Shift Pressure Upshift on the 2-3 change) the A6 basically stops flaring immediately and starts shifting beautifully. Bare in mind though, my flaring issue is not the same is those out there experiencing a one off flare on the first 2-3 shift. Mine is a continual flare on that shift.

I have attached my tune so you can compare it to your tunes and/or the stock tunes. Just in case you can't read the OS it's "24243170" which I think is different to the ones in USA but I'm not sure