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A8 performance shift problem

 
Old 05-21-2019, 07:58 PM
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64modified
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Default A8 performance shift problem

I’ve noticed a potential issue and wonder if it’s happened to anyone else...

I almost always shift the car manually (paddles) and almost always drive in Tour mode. When I really get on it, it shifts in Performance Shift Mode (which is awesome!) However, recently, the car appears to ‘forget what it is’ and shifts normally (regardless of acceleration). If I turn the car off and back on again, it goes back to using PSM under hard acceleration.

So, has this happened with anyone else’s car? If so, what was the problem and how did you fix it?

I’ve read elsewhere that PSM was only ‘supposed’ to work in Sport/Track mode, but mine has always worked in Tour as well - so I don’t think that’s the problem. Any thoughts on what might be happening are appreciated - thanks!
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Old 05-22-2019, 07:12 AM
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I've never noticed it coming on at all when using paddles in sport. Today was the first time I've seen it in a long time and that was in sport mode not using paddles.
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Old 05-22-2019, 07:39 AM
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I would agree, I have not seen that in sport mode either..I don't use paddles much in touring mode
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Old 05-22-2019, 07:53 AM
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I've only seen it in sport or track with shifter in D and not using the paddles......enables by quickly flooring and letting off throttle......works great and very consistent.....if you don't drive aggressive after about 10 seconds it goes back to normal.

Per GM's Tadge -
When you see the 'Performance Shift Active' message that means you have engaged a set of features we call PAS/PAL. PAS stands for Performance Algorithm Shift. PAL refers to Performance Algorithm Lift-foot. We, like many manufactures, try to have the car adapt to the way it is being driven. Sensors on the car detect things like the rate of steering wheel rotation, rate of change of throttle position and vehicle lateral acceleration. PAS/PAL are just a couple of features that fall into this category and they only affect how the transmission shifts gears.
The performance shift algorithm is an 8-speed paddle shift automatic feature that operates in Sport and Track mode with the shifter in “D”. Sport mode enables the lift-foot algorithm, Track mode additionally enables PAS which brings lateral acceleration into the equation. PAS is the more aggressive level of performance shift, it will force the lowest possible gear for a given speed range. Lateral acceleration plays a role in activating the feature and is also used to negotiate gear state, for example: Downshifts are not allowed above a certain lateral acceleration (don't want to have any abrupt torque changes that might disturb the chassis).
During an acceleration PAL is activated during a lift-foot throttle maneuver which is calibrated above a threshold pedal position and a calibrated pedal rate of return. These calibration values are set to prevent the algorithm from activating during normal driving conditions. Unlike PAS which selects the lowest available gear, the lift-foot algorithm will hold the gear the transmission is currently in until it times out (then normal shifting will begin).
There is a bit more to these features than I am sharing here and you can tell I'm not disclosing any specifics around the calibration for our algorithms. That is intentional. I always want to share as much as I can when answering these questions, but I have to balance customer's desire for specific information and spoon-feeding our competitors’ valuable proprietary information that would be expensive and difficult for them to obtain through other means.
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Old 05-23-2019, 01:38 AM
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Flooring and letting off the throttle while driving?? Sorry, never have seen this come up on my car...
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Old 05-23-2019, 06:41 AM
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Originally Posted by Vegas1500 View Post
Flooring and letting off the throttle while driving?? Sorry, never have seen this come up on my car...
On an A8 with it in auto, to get into performance shift mode put in sport or track mode and just stab the throttle and let off really quick....goes right in.
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Old 05-23-2019, 10:06 AM
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Unless the car is cold and I am waiting for it to warm up, I always drive in manual mode. And I love it.
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Old 05-23-2019, 10:49 AM
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Wish there was a way to manually enable PSM without the short timeout.
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Old 05-23-2019, 01:01 PM
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Originally Posted by wagoetzmann View Post
On an A8 with it in auto, to get into performance shift mode put in sport or track mode and just stab the throttle and let off really quick....goes right in.
Agreed. Paddles feel sluggish even in track mode but this method will give you crisp shifts without wringing out the RPM's
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Old 05-25-2019, 02:38 AM
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Originally Posted by wagoetzmann View Post
On an A8 with it in auto, to get into performance shift mode put in sport or track mode and just stab the throttle and let off really quick....goes right in.
While in “Drive” or in Neutral before shifting to drive?
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Old 05-25-2019, 01:42 PM
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Originally Posted by Vegas1500 View Post
While in “Drive” or in Neutral before shifting to drive?
"Per GM's Tadge - The performance algorithm shift is an 8-speed paddle shift automatic feature that operates in Sport and Track mode with the shifter in “D”. "

Just drive down the highway in D and sport or track mode and stab the throttle then let off quickly...….goes right into PAS.
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Old 05-25-2019, 10:13 PM
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The only way you could "trick" the car into keeping it active without stomping your gas and then brakes over and over as you drive down the road, is to find the lateral G meter, and send back high false values to the car's computer while you are still driving straight.

I am surprised no one has done this yet honestly, would not be hard to do.

Higher lateral G's activate and maintain the performance race shifting mode to remain active.

Have the lateral G readout from the sensor spike to 1 lateral g every 6-8 seconds, and it should stay active.

It will be curious what the car does if it sees it is driving straight and is pulling 1 lateral G, if there are any other goofy negative side effects.

Last edited by bbbvettes.com; 05-25-2019 at 10:16 PM.
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Old 05-26-2019, 12:33 AM
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Originally Posted by bbbvettes.com View Post
It will be curious what the car does if it sees it is driving straight and is pulling 1 lateral G, if there are any other goofy negative side effects.
I'm sure my DSC suspension controller would not work correctly anymore ……….
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Old 05-26-2019, 07:29 AM
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Default Question

I like the paddles but in this C7 Z vs my C6 the engines starts to get warmer much faster. I do shift quickly and that was my understanding to keepntemos down but seems to still go over 205. Any thoughts or ideas or comments. I stay away from It because of this and really would like to go back to using them more than not. Thx
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