A8 tuning to fix shudder
01-16-2019, 09:17 PM
#1
Drifting
Thread Starter
A8 tuning to fix shudder
Hey guys, can anyone tell me, specifically, what needs to be addressed in the tune to fix the dreaded shudder issue on the A8? Mine is a 2015, and I know tuning is available. I would like to be able to share with my tuner so we aren't randomly adjusting things. I do realize that tuning is an art, but I'm hoping that someone can share a few 'secrets' to help the entire C7Z family. It sounds like the 2019 "fix" is just another fluid change? They have a new synthetic fluid that will be released in February, I guess? Not convinced that this is going to fix the shudder. I've already had the latest fluid change and it's still there.
01-16-2019, 09:33 PM
#2
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gm tries to keep the converter locked way too much and it's not robust enough to handle it. unlock the converter except during cruise in higher gears and when you do lock it, make sure it's locked down tight.
also, I didn't include it since it is a given, but also turn off AFM.
also, I didn't include it since it is a given, but also turn off AFM.
Last edited by Higgs Boson; 01-17-2019 at 07:45 AM.
01-17-2019, 09:47 AM
#4
Drifting
01-17-2019, 11:29 AM
#5
I am no authority on this subject (Higgs is), but the tuner I spoke with told me it is a fairly simple adjustment while making an engine tune that can eliminate the cylinder deactivation. My personal concern on this subject is if my new car experiences any kind of drive train warrantable problem in the early stage of ownership (say under 5000 miles), I want to be sure I have it covered under the GM warranty. A tune would very likely eliminate that coverage.
01-17-2019, 06:02 PM
#6
I am no authority on this subject (Higgs is), but the tuner I spoke with told me it is a fairly simple adjustment while making an engine tune that can eliminate the cylinder deactivation. My personal concern on this subject is if my new car experiences any kind of drive train warrantable problem in the early stage of ownership (say under 5000 miles), I want to be sure I have it covered under the GM warranty. A tune would very likely eliminate that coverage.
01-17-2019, 06:42 PM
#7
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01-17-2019, 08:00 PM
#8
You can stay away from any potential tune complications by simply plugging in a Range module. That will kill the AFM as long as it's in and will never affect the rest of the vehicle operation and will not cause a problem with any warranty situation. All you need to do when taking it to a dealer for work is to unplug it. There's no traceable record of it in the ECM.
01-17-2019, 08:35 PM
#9
Drifting
Thread Starter
Guys, this thread was started to discuss A8 tuning and fixing the shudder issue. Can we please stay on topic. There are plenty of threads on AFM. I would like to learn about the shudder issue and who has been able to fix it with tuning. Thanks!
01-17-2019, 09:13 PM
#11
Drifting
Thread Starter
Originally Posted by pkincy
Well the AFM gets a lot of blame for contributing to shudder, but remember that the shudder problem is across all the GM A8s and many of them do not have AFM.
01-17-2019, 09:46 PM
#12
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i have not found afm and TC issue to be related, AFM active can feel very juddery but it is not the same issue so I can see people thinking disabling AFM cures TC shudder.
my 2015 6.2 silverado (that I got rid of at 5000 miles due to A8 issues) had disabled AFM in the tune and felt like I was driving off road, lol. no thanks.
my 2015 6.2 silverado (that I got rid of at 5000 miles due to A8 issues) had disabled AFM in the tune and felt like I was driving off road, lol. no thanks.
01-17-2019, 10:47 PM
#14
As explained in other posts, the AFM system is highly suspect in the A8 shudder problem due to the fact that it causes the TC to clutch and declutch excessively so the problem isn't actually the tranny, it's the TC where the shudder is coming from. The original fluid is also implicated but the two taken together seem to cause the problem sometime after the 6K mileage point. Given that apparent casual linkage, I think the comments are not off-topic. OP wants to eliminate the shudder problem with a tune to eliminate the the AFM which will probably work but as another poster has pointed out, there goes your drive-train warranty. The Range module works, it's simple and won't affect the warranty. How is this off topic?
01-17-2019, 11:30 PM
#15
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As explained in other posts, the AFM system is highly suspect in the A8 shudder problem due to the fact that it causes the TC to clutch and declutch excessively so the problem isn't actually the tranny, it's the TC where the shudder is coming from. The original fluid is also implicated but the two taken together seem to cause the problem sometime after the 6K mileage point. Given that apparent casual linkage, I think the comments are not off-topic. OP wants to eliminate the shudder problem with a tune to eliminate the the AFM which will probably work but as another poster has pointed out, there goes your drive-train warranty. The Range module works, it's simple and won't affect the warranty. How is this off topic?
the range module may help band-aid one of the "casual links," as you state, but it is not a cure.
01-18-2019, 12:04 AM
#16
Drifting
Thread Starter
Guys, I was not aware that AFM had anything to do with the shudder. Since mine has been turned off for almost a year, why am I still experiencing shudder?
01-18-2019, 12:28 AM
#17
Burning Brakes
I had mine tuned at approximately 4800 miles.
First order of business is to remove the TCU from the right rear of the car and send it to HP Tuners.
They will then "unlock" it so the tune can be performed.
It takes all of 10 minutes to have it out and in your hands.
Once it comes back from HP, install and drive as before until the tune is performed.
I had NicD at Corde's perform the tune along with other mods.
First off the part throttle shifts are firmed up and the lazy feeling is all but gone.
AFM was turned off at this time as well. I assume Nic does this automatically.
Full throttle shifts happen right now and all occur at about 6400 RPM.
The car now has 8200 miles showing without any issues from the TCU tune.
Mine never exhibited the dreaded shudder and the fluid has never been changed.
My Z06 is a 17.
Would I do it again? YES!
First order of business is to remove the TCU from the right rear of the car and send it to HP Tuners.
They will then "unlock" it so the tune can be performed.
It takes all of 10 minutes to have it out and in your hands.
Once it comes back from HP, install and drive as before until the tune is performed.
I had NicD at Corde's perform the tune along with other mods.
First off the part throttle shifts are firmed up and the lazy feeling is all but gone.
AFM was turned off at this time as well. I assume Nic does this automatically.
Full throttle shifts happen right now and all occur at about 6400 RPM.
The car now has 8200 miles showing without any issues from the TCU tune.
Mine never exhibited the dreaded shudder and the fluid has never been changed.
My Z06 is a 17.
Would I do it again? YES!
Last edited by Mike Jesse; 01-18-2019 at 12:33 AM.
01-18-2019, 07:02 AM
#18
01-18-2019, 10:48 AM
#19
Drifting
Thread Starter
Originally Posted by tertiumquid
Your TC was already damaged by the time you did the mod.
