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Tune issue on my A8?

 
Old 10-29-2018, 02:10 AM
  #21  
RoxyCarter
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It should not be doing this. Some do however. The torque converter is slipping after the shift. It happens at higher speed due to wind resistance in addition to car utilizing full power. This is most resistance/load against the converter and trans in the higher gears at wot.

I too have noticed some cars doing it at the strip. But it can be repaired. Ask for a new torque converter. If your car is tuned and out of warranty, then find a GOOD trans tuner, (not a tuner who says it is normal) plenty of video of stock tune cars which shift properly, can be uploaded to prove it is not normal.

it can and should be fixed.

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Old 10-29-2018, 08:32 AM
  #22  
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Originally Posted by GeorgeR_Zed06 View Post
Lol, that's probably nothing more than the performance traction management controlling wheel spin and backing it off a tad. Mine does the same thing too and with all nannies turned off, it doesn't hook up completely till about 90-95 mph. So yeah, I can see PTM and TM kicking in at those lower speeds under full throttle.
Originally Posted by Warp Factor View Post
At 125 mph?
Originally Posted by GeorgeR_Zed06 View Post
Yup, or at least mine does...
You are breaking traction at 125 mph under straight-line acceleration on dry pavement? At what temperature, with what tires, and what are your mods?

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Old 10-29-2018, 01:08 PM
  #23  
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Originally Posted by RoxyCarter View Post
It should not be doing this. Some do however. The torque converter is slipping after the shift. It happens at higher speed due to wind resistance in addition to car utilizing full power. This is most resistance/load against the converter and trans in the higher gears at wot.

I too have noticed some cars doing it at the strip. But it can be repaired. Ask for a new torque converter. If your car is tuned and out of warranty, then find a GOOD trans tuner, (not a tuner who says it is normal) plenty of video of stock tune cars which shift properly, can be uploaded to prove it is not normal.

it can and should be fixed.
There is nothing to fix, this is factory behavior as intended. The converter is set to lockup after that shift and it's simply the converter lock up finally biting down. The factory programming is set to ramp up to the pressure that achieves lockup, not just hit with full pressure. The ramp pressure tables that are available in any editor like HP Tuners or EFI Live will alter this behavior but you really don't want to as you can induce drivetrain ringing in other gears when it locks up under part throttle. Again, GM didn't guess when they set it up this way it was done for a reason.
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Old 10-29-2018, 01:55 PM
  #24  
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Originally Posted by NicD View Post
There is nothing to fix, this is factory behavior as intended. The converter is set to lockup after that shift and it's simply the converter lock up finally biting down. The factory programming is set to ramp up to the pressure that achieves lockup, not just hit with full pressure. The ramp pressure tables that are available in any editor like HP Tuners or EFI Live will alter this behavior but you really don't want to as you can induce drivetrain ringing in other gears when it locks up under part throttle. Again, GM didn't guess when they set it up this way it was done for a reason.
Then why has my untuned '17 never done it, and why have I seen so many dragstrip and racetrack videos where other Z06's didn't do it? Did GM change the programming at some point?
Seems like that much slippage at full throttle would be danged hard on the converter clutch.

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Old 10-29-2018, 02:31 PM
  #25  
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Originally Posted by Warp Factor View Post
Then why has my untuned '17 never done it, and why have I seen so many dragstrip and racetrack videos where other Z06's didn't do it? Did GM change the programming at some point?
Seems like that much slippage at full throttle would be danged hard on the converter clutch.
The more power it makes the more it's going to slip upon it's commanded soft apply, the TCM is also constantly learning and adapting so no two shifts are identical no matter what. The apply ramp table is identical between the C7s, Z06s, and Camaros actually so it will vary with horsepower, conditions, etc. Also keep in mind that there have been several revisions of torque converters over the years with differing lockup clutch materials and fluid changes so that will cause differences as well. It's not a bad thing, it's just different.
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Old 10-30-2018, 10:28 AM
  #26  
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Great info @NicD Thank you!
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Old 10-30-2018, 11:37 AM
  #27  
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NicD has serious knowledge. Learned a lot from him since the LS1Tech days.
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Old 10-30-2018, 12:06 PM
  #28  
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I must be missing the boat somewhere, so pardon my ignorance in advance...

NicD, you are describing this phenomenon as "torque converter lockup". Making sure I am on the same page here... I assume you are implying that the lockup happens AFTER the slip occurring.

My point of view is that the cars that do not have this 3 second slip, are already locking out instantly after the shift. Thus, there is no "slip" that ever occurs in the cars that lock out instantly.

So to describe this slip phenomenon as "lock up" or "lock out" seems very counter intuitive to me. They all lock out. They don't all slip before hand.

The RPM coming back down to where it should be is not the problem, this lock out is a good thing.

The question is, why does it take 3 seconds to occur on some cars, and happens instantaneously on others? As roxy mentioned, this slip may be due to a failing/slipping torque converter.

The other fear I would have is, does the car limit power output to give the torque converter a break from stress, when it senses this slip, to give the torque converter a chance to regain grip so that it can then lock out? That would easily account for slower times at the strip when this slip phenomenon occurs.

Last edited by HessViper; 10-30-2018 at 12:12 PM.
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Old 10-30-2018, 01:27 PM
  #29  
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Originally Posted by HessViper View Post
I must be missing the boat somewhere, so pardon my ignorance in advance...

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Old 10-30-2018, 04:37 PM
  #30  
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I gave you the benefit of the doubt NicD to explain why auto transmission 101 does not apply to this situation, and you respond with that? typical.

To the OP, this situation is nothing new, anyone who works on automatic transmissions can explain this is a common problem that occurs on TC on all automatic vehicles.

As time goes on, the torque converter slips in taller gears, more than it was designed to slip. The 2 solutions are to either replace the TC and/or its fluid, or have the tune changed.

As NicD explained, there is a ramp up of clamping pressure to cause the TC to lock out and match/lock speed between the drive line and the engine.

If this ramp up clamp rate is too lax, then there is unwanted slippage, which actually does unwanted additional wear to the TC.

If it engages too fast/hard, then there is a rough slam every time the car switches gears. The goal of course, is the happy medium. Not slam, but not slip for 3 seconds.

If the car is taken to a chevy store and still has a warranty, they should flush the TC fluid, and if that does not solve it, then they should replace the TC. They of course will not touch the factory transmission programming unless GM gets involved (unlikely)

If the car is aftermarket and making extra power, and has an aftermarket tune, then you will need an aftermarket tune for the TC/trans also, which enhances the TC clamp rate, to keep this slipping from occurring in the taller gears.

Back to anyone who says this symptom is "normal", then why is it 3 out of 3 z06 I have been in that are automatics do not do this, nor does warp factor's car, nor countless videos on the internet of other cz7 automatics? And why is it most common only on higher HP cars?

Meanwhile, if you see the ones who have this slip issue, you will see in the you tube video comments of reputable shops suggesting a better trans tune.

As far as "damaging the TC" by having it too severe, keep in mind, the constant among all gears is the rear tires, and their ability to break loose and take the stress off the driveline when they do break loose.

If one has drag tires and drag wheels on that get exceptional grip, it is an understood reality that this setup is harder on the drive line components of any vehicle, vs, the stock rear wheel and tire setup which will spin. However, having a TC slip for 2 or 3 seconds each time one hits 125mph, let alone any gear shift above that speed, is not a good situation for predictable handling, let alone being good for the longevity and reliability of the TC... in my opinion.

but in case I am wrong,

Consult any basic auto transmission shop to find out this slippage is not ideal. Then track down a reputable one great at solving this problem on these vehicles to actually tune your transmission/TC properly.

Saying all cars have this tune and thus the slip is acceptable, is like saying all cars have pre-detonation knock detection programming, and therefore engine knock and timing pull are 100% factory intended behavior of vehicles at all times. Not the case in the least.

PS, apparently I am Satan for having this opinion
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Old 10-30-2018, 06:56 PM
  #31  
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Hook line and sinker, every damn thread these clowns crap in and it just becomes a steaming pile of **** with endless babble. Aren't there any moderators to get rid of these clowns? GM has been using the same damn TCC strategy since 2006 with the 6L80 so it's nothing new, it's a soft ramping apply after a minimal test period to verify response with only the required amount of pressure applied to achieve the desired slip level. The 8L90 commands anywhere from 20 - 100 rpms worth of slip at all times under part throttle in 4 cylinder mode. The 6L80s used to command anywhere from 10-20 rpm worth of slip even under WOT. You are about 12 years behind on this conversation and whoever told you your opinion was worth anything to begin with is wrong also. Oh yeah, catch up on your memes Mike. LOL
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Old 10-30-2018, 08:18 PM
  #32  
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Nic, why is it programmed to do this only on the 4-5 shift (and a little on the 3-4 shift in one of the videos?
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Old 10-30-2018, 11:12 PM
  #33  
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We are sitting here laughing, trying to figure out what his point even is.

think about this for a moment...

I say it's the TC slipping and a mechanical issue.

he says all the cars have the same programming. That, I agree with.

so then we observe there are 2 types of autos, the ones that are slipping and the ones that dont.

people who have the ones which slip, start a thread saying they want their cars to not do this and want to be like the cars that don't slip, so I suggest different fluid or a new TC.

he gets angry, tells me I'm wrong, and then in so many words, he states that the programming is the same on them all, but the TC and the fluid is not a constant. (I Agree)

...

which means if a person does not like their car to slip... what is the only solution?

change the TC and/or the fluid.

but instead of say he agrees, he starts bragging that he understands how the computer is programmed in all the cars... which is the constant variable.

then he tells me I'm wrong about being able to fix the car to prohibit the slip.

Then he puts up memes that we are Satan. Lol.

I've never met people so eager to argue about nothing.

if someone does not like their TC slipping, replace it.

the end. We don't care about the constant denominator... of how the programming works.

we assumed it was constant. This is not profound info.

next thing you know, he will be arguing that the cars that don't slip, are the ones that are flawed.

or better yet, he will be saying that ones that slip and the ones that don't slip, are actually exactly the same... and the rest of us can't observe life and our vettes accurately, since the program is constant and that then means that no torque converter anywhere in any vette can slip anymore or less than any other. We are all just imagining it, thus his statements of "there is nothing to fix, it is 100% how the factory wanted the car to be" then would make sense.

think about this... from his point of view.. either...

the factory meant for them all to slip different amounts..
or the factory intended them all to slip the same, which they all do, and we are imagining a difference which is not there... since there is no issue to solve

am I the only one laughing at how dumb this discussion is right now? Lol

seems to me, the guy might have tuned a couple cars that do this, and since he can't fix it easily, he is running around telling everyone it is normal. Otherwise, I see no point in telling someone their slipping TC is normal... when most z06 don't do it... which is the opposite of "normal"

I guess all the new vettes on chevy showrooms are broken

they should all have 3 seconds of slip

you can't make this stuff up.

Last edited by RoxyCarter; 10-30-2018 at 11:56 PM.
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Old 10-31-2018, 09:19 AM
  #34  
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My second point was...

if the car is making extra power, then the trans/TC needs tuned to bite harder. A new TC will still slip as the programming does not match the new torque of the engine.

no TC is supposed to slip for 3 seconds on a shift from 4th to 5th. After being programmed to bite harder/sooner, the car will feel normal again.

I guess if I had a lot of customers out there, who's TC slip, and I tuned their cars, if I had a narrow selfish point of view, I would refer to anyone who explains the truth to my customers, as Satan as well.

such people would cause me to have to go back to work on a lot of cars.

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Old 10-31-2018, 09:57 AM
  #35  
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I spoke with my tuner yesterday as I am dropping the car off for blower porting and bigger TB tomorrow...he said it's most likely in the tuning and the sometimes the torque management will slightly close the fueling, which causes this issue. He also said he has seen it before and it can be fixed with tuning...I appreciate everyones input and by all means keep the discussion going. I will update on my end as well once I hear back from my tuner....he is going to do some data logging as well.
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Old 10-31-2018, 12:07 PM
  #36  
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Originally Posted by Chi-Town ZR1 View Post
I spoke with my tuner yesterday as I am dropping the car off for blower porting and bigger TB tomorrow...he said it's most likely in the tuning and the sometimes the torque management will slightly close the fueling, which causes this issue. He also said he has seen it before and it can be fixed with tuning...I appreciate everyones input and by all means keep the discussion going. I will update on my end as well once I hear back from my tuner....he is going to do some data logging as well.
Well there is one thing that won't cause it and it's anything to do with fueling. One common bad thing that I see in tunes that can screw up shifts, etc is cutting down the torque model to try to prevent the throttle body from closing, this tells the TCM the engine is producing less torque which throws off it's calculations for line pressures on shifts and lockups.

Originally Posted by Warp Factor View Post
Nic, why is it programmed to do this only on the 4-5 shift (and a little on the 3-4 shift in one of the videos?
You would have to ask the GM calibration guys about that. It's set to lockup fully at WOT just after the 4-5 shift and you can watch the lockup start to command just a bit on the 3-4 shift if you watch a log file monitoring the TCC apply pressures, etc.
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Old 10-31-2018, 12:19 PM
  #37  
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Originally Posted by RoxyCarter View Post
We are sitting here laughing, trying to figure out what his point even is.
The part that makes me laugh is you are conflating actual transmission slip with TCC apply. One is bad, one is normal and programmed as such, the videos posted in this thread are pretty typical just showing the TCC locking up depending on the year/converter/fluid used and the apply/full lockup lasts all of a half a second not anywhere near 3 seconds. I've seen plenty of bad tunes where the tuners solution is to cut down the torque model to prevent the throttle body from closing, of course this screws up commanded pressures in the trans and cause all sorts of other issues with shifts and lockups but having an accurate or slightly high torque model doesn't preclude this half a second TCC apply/lockup behavior.

The funniest part though is that I can imagine you guys cuddling up to each other on the couch desperately trying to do research on GM's TCC lockup strategy and pounding away on that keyboard. I just can't figure out if these two new accounts are just Mike or if you really just have multiple personalities. I guess a simple IP search by an admin would give the answer because I highly doubt you are technical enough to hide your IP. I mean at least try to type in a different way or alter your posting style.
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Old 10-31-2018, 12:38 PM
  #38  
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Old 11-01-2018, 12:11 AM
  #39  
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You keep copping out and saying the tc is programmed to behave this way.

correct.

and the air fuel ratios and torque management are programmed to behave a certain way as well

And when a person does things to their car that make more power... those programs need to be altered.

this is why you have a job NicD.

You keep pretending the program on the stock tune does not need to be altered under any circumstance.

it's funny.

why do you have a career if the stock tunes are adequate? By now the OP has located someone useful to adjust the TC programming. You're still here just trying to pick fights.
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Old 11-01-2018, 04:29 PM
  #40  
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I guess I'll just have to take solace knowing that I tuned the quickest/fastest stock LT4 blower car on record and it didn't even take negative DA to do it, where as you'll just have to talk about things you don't understand on the internet.
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