A8 Problem?
Thread Starter
Le Mans Master
Joined: Mar 2000
Posts: 9,127
Likes: 2,326
From: Pottsville, PA. USA Home Of America's Oldest Brewery Yuengling
A8 Problem?
I was driving my 2015 Z-51 A8 with 2,700 miles on it today on the Interstate. I was one mile from my exit passing an 18 wheeler going about 70. I punched it down and ran up to 105 and let off. As I was slowing down to 55 to exit the car was racing and the tach was at 3500 rpms. When I got stopped at the exit the car seemed like it was still in an upper gear. The car was racing and wouldn't shift normal. I pulled out and started driving and it went back to normal. I didn't get a chance to punch it down again to see what would happen?
My first thoughts were this seem like a computer problem? What is the TSB for the transmission?
Any thoughts?
My first thoughts were this seem like a computer problem? What is the TSB for the transmission?
Any thoughts?
Last edited by Corvette ED; Nov 1, 2015 at 09:03 PM.
Burning Brakes
Joined: Aug 2014
Posts: 990
Likes: 207
From: Bay Area CA
I was driving my 2015 Z-51 A8 with 2,700 miles on it today on the Interstate. I was one mile from my exit passing an 18 wheeler going about 70. I punched it down and ran up to 105 and let off. As I was slowing down to 55 to exit the car was racing and the tach was at 3500 rpms. When I got stopped at the exit the car seemed like it was still in an upper gear. The car was racing and wouldn't shift normal. I pulled out and started driving and it went back to normal. I didn't get a chance to punch it down again to see what would happen?
My first thoughts were this seem like a computer problem? What is the TSB for the transmission?
Any thoughts?
My first thoughts were this seem like a computer problem? What is the TSB for the transmission?
Any thoughts?
When you mash the loud pedal, the car shift algorithm changes such that the car stays in gear longer and won't upshift assuming you are asking for more performance. The transmission will return to normal shifting when you let off the pedal long enough, or you can hold the upshift paddle and it will return to normal shifting (if you are not in manual shift mode).
Last edited by Skidplate; Nov 1, 2015 at 09:44 PM.
Team Owner
Joined: Sep 2005
Posts: 20,352
Likes: 568
From: Ventura County, Calif
You didn't say what "mode" you were in but.....yea, sounds like Performance Shifting:
https://www.corvetteforum.com/forums...ng-active.html
https://www.corvetteforum.com/forums...ng-active.html
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
Ed, part of what you describe sounds like exactly what happens when the performance algorithm is activated which provides more aggressive gear selection by holding the lower gear assuming you will be continuing with aggressive driving. This has been included in the programming of a number of GM automatic transmissions for close to a decade now. However I am not exactly sure what you mean by being stopped at the exit and the transmission was in a higher gear with the car (engine?) racing? If you literally were at a stop with brakes applied then that certainly isn't normal but if you meant you were just driving slowly after coming off the interstate it could well have stayed in the performance shift mode since turns/curves are one of the parameters that engages this mode.
Last edited by NSC5; Nov 1, 2015 at 09:13 PM.
Thread Starter
Le Mans Master
Joined: Mar 2000
Posts: 9,127
Likes: 2,326
From: Pottsville, PA. USA Home Of America's Oldest Brewery Yuengling
You didn't say what "mode" you were in but.....yea, sounds like Performance Shifting:
https://www.corvetteforum.com/forums...ng-active.html
https://www.corvetteforum.com/forums...ng-active.html
Ed, part of what you describe sounds like exactly what happens when the performance algorithm is activated which provides more aggressive gear selection by holding the lower gear assuming you will be continuing with aggressive driving. This has been included in the programming of a number of GM automatic transmissions for close to a decade now. However I am not exactly sure what you mean by being stopped at the exit and the transmission was in a higher gear with the car (engine?) racing? If you literally were at a stop with brakes applied then that certainly isn't normal but if you meant you were just driving slowly after coming off the interstate it could well have stayed in the performance shift mode since turns/curves are one of the parameters that engages this mode.
Burning Brakes
Joined: Aug 2014
Posts: 990
Likes: 207
From: Bay Area CA
If you put the transmission in Manual mode and shift with the paddles, you will have complete control.
Last edited by Skidplate; Nov 1, 2015 at 09:48 PM.
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
It is actually a very nice feature once you get used to it and the intent is to provide the maximum performance possible. It is disconcerting the first time you experience it. I had just gotten through the break-in period of my 2008 Cadillac CTS when I first experienced the PAS/PAL (Performance Algorithm Shifting/Performance Algorithm Liftfoot) behavior. I had gone to near full throttle on an interstate on-ramp after the mini-van in front of me decided to pull off on the shoulder midway down the ramp and once on the interstate the transmission stayed in a lower gear for a short time leading you to first believe you are in some sort of limp mode. GM really needs to explain this behavior very early in the manual because there are a lot of questions/concerns across the various models from owners who aren't familiar with this behavior.
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My A6 does it also and I like it makes my automatic feel like a manual tranny in some ways!
Team Owner
Joined: Apr 2001
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From: S.W. Ohio. . . . . . NRA Life Member
EXACTLY !
The first time it went into Performance Shift mode, I was like... WTF ???
No doubt it is new, and therefore unusual. But, now that I know what it does and why... I like it
Melting Slicks
Joined: Mar 2013
Posts: 3,104
Likes: 626
From: Baton Rouge LA
Mine moves out of PS mode faster in Touring and Eco modes, which is why I've been using Touring mode most of the time. In most conditions I don't need Performance Shifting to be activated and in those times find it irritating.
Last edited by iclick; Nov 2, 2015 at 01:34 PM.