Getting concerned-A8 issues?
Pro
Joined: Jul 2014
Posts: 549
Likes: 41
From: Kansas City MO
Well, one example of safe & legal WOT is entering the Interstate and going from 0-65 in an expeditious manner. Passing on an Interstate or on a two lane country road. Even on a metro street, a brief 0-45 WOT could be safe & legal.
Melting Slicks
Joined: Mar 2013
Posts: 3,104
Likes: 626
From: Baton Rouge LA
Originally Posted by BladeSilver2015
In my view it is UNSAFE to operate the C7 on public roads at WOT in just about any situation. On the track it is a different story.
FWIW, mine is shifting quite nicely since doing the latest software update and "fast learn" procedure.
Last edited by iclick; Dec 23, 2015 at 01:52 PM.
Drifting
Joined: May 2015
Posts: 1,412
Likes: 140
Burning Brakes
Joined: Jul 2015
Posts: 920
Likes: 87
Racer
Joined: Aug 2007
Posts: 354
Likes: 101
From: Louisville Ky
Racer
Joined: Aug 2007
Posts: 354
Likes: 101
From: Louisville Ky
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Pro
Joined: May 2015
Posts: 586
Likes: 124
From: Florida
Racer
Joined: Aug 2007
Posts: 354
Likes: 101
From: Louisville Ky
My trans fianally got replaced but what people don't understand when they say trade or lemon law it is you lose money, if you trade you lose. if they refund what you paid for the car and it is not the current year model you are out more money to replace it. all most people want is their car repaired without all the hassle from GM
Last edited by red 1; Dec 23, 2015 at 10:45 PM.
Pro
Joined: Jul 2015
Posts: 579
Likes: 56
From: Sarasota Florida
I have a 2016 shifts from 1 to 2 at first were smooth with a rare harsh shift, with 4k+ now it happens every time I take the car out and starting to be a real bother when wife is with me. Recently a few shifts that were truly jarring! Such that I looked here to find information as to if me or the car. So yeah at least one 16 has issues.
Thread Starter
Le Mans Master
Joined: Sep 2012
Posts: 7,146
Likes: 1,940
From: Hagerstown MD
St. Jude Donor '15-'16,'18
I have a 2016 shifts from 1 to 2 at first were smooth with a rare harsh shift, with 4k+ now it happens every time I take the car out and starting to be a real bother when wife is with me. Recently a few shifts that were truly jarring! Such that I looked here to find information as to if me or the car. So yeah at least one 16 has issues.
Pro
Joined: May 2015
Posts: 586
Likes: 124
From: Florida
My trans fianally got replaced but what people don't understand when they say trade or lemon law it is you lose money, if you trade you lose. if they refund what you paid for the car and it is not the current year model you are out more money to replace it. all most people want is their car repaired without all the hassle from GM
I understand completely. At the same time, I for one will not tolerate any new car with major drive train issues. Have you seen some of the pictures on this forum of a C7 that has been gutted to do transmission repairs? Perhaps you saw your own car when it was being repaired. No way I would want the car after that. Although I do not expect any problems at this point, if my C7 ever has a major engine or transmission issue, I will have it repaired under warranty and then trade it and move on to something else. I have done this many times in my lifetime including a 1984 C4 I bought new.
Last edited by BladeSilver2015; Dec 24, 2015 at 12:04 PM.
Burning Brakes
Joined: Jul 2015
Posts: 920
Likes: 87
Google GM TSB 14-07-30-001c
Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts – 2015 GM Vehicles
BY VITALY
ON JANUARY 27, 2015
IN 2015, CADILLAC, CHEVROLET, CORVETTE, DIAGNOSTIC TIPS, ESCALADE, GMC, SIERRA, SILVERADO, TRANSMISSION, YUKON
Information on Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts – (Jan 27, 2015)
Subject:
Information on Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts
Models:
2015 Cadillac Escalade, Escalade ESV
2015 Chevrolet Corvette, Silverado
2015 GMC Sierra, Yukon, Yukon XL
Equipped with 8L90 Automatic Transmission (RPO M5U)
Attention:
This Bulletin also applies to any of the above models that may be Export vehicles.
Some customers may comment on low mileage vehicles with automatic transmission that shift feel to be too firm (harsh) or may slip or flare. Customers should be advised that the transmission makes use of an adaptive function that will help to refine the shift feel while driving and improve shift quality.
Transmission Adaptive Functions
The Hydra-Matic® 8-Speed RWD transmission utilizes a line pressure control system during upshifts to compensate for new transmission build variation as well as the normal wear of transmission components. The variation experience on a new and normal wear of the apply components within the transmission over time can cause shift time (the time required to apply a clutch) to be longer or shorter than desired.
In order to compensate for these changes, the transmission control module (TCM) adjusts the pressure commands to the various pressure control (PC) solenoids to maintain the originally calibrated shift timing. The automatic adjusting process is referred to as “adaptive learning” and it is used to ensure consistent shift feel plus increase transmission durability.
The TCM monitors the A/T input speed sensor (ISS) and the A/T output speed sensor (OSS) during commanded shifts to determine if a shift is occurring too fast (harsh) or too slow (soft) and adjusts the corresponding PC solenoid signal to maintain the set shift feel. The purpose of the adapt function is to automatically compensate the shift quality for the various vehicle shift control systems. The adapt function is a continuous process that will help to maintain optimal shift quality throughout the life of the vehicle.
How to Adapt Your Transmission
Transmission adapts can be reset and relearned on most vehicles through GDS 2 by using the Transmission Adaptive Values Learn procedure. This procedure is completed in the service stall and no vehicle driving is required.
To complete the Transmission Adaptive Values Learn procedure enter GDS 2 Diagnosis and navigate to:
Module diagnostics
Transmission Control Module
Configuration / Reset Function
Transmission Adaptive Values Learn
Transmission Adaptive Values Learn is the recommended method to reset and relearn the adapts. This procedure is available on all trucks. This procedure is also available on Corvettes built on September 29, 2014 or later. Use the Investigate Vehicle History (IVH) to verify the build date of a Corvette.
Important: Transmission Adaptive Values Learn is shown as an available GDS 2 procedure on all 2015 Corvettes built before September 29, 2014. This method is not effective and will not reset and relearn the adapts. These cars must be driven to learn the adapts.
For Corvettes built before September 29, 2014 the Hydra-Matic® 8-Speed RWD transmission adaptive learn process can only be accomplished by driving in the following manner. Execute the steps below with the vehicle warmed up on a smooth level road. The driver may observe a brief pulse behavior or firm shift feel while the transmission is optimizing the clutch learn characteristics.
Perform a test drive and note any soft or harsh shifts.
To improve these complaint shifts, locate the clutches that need to be learned in the following table below, and perform the required learning procedure for each clutch listed below the chart.
Note: The transmission fluid temperature must be between 75°C (167°F) and 85°C (185°F) during the drive procedure or adapts will not be learned.
To Correct The Shift Feel
Learn These Clutches
Applying Clutch
Releasing Clutch
1–2
C4
C3
2–3
C3
C1
3–4
C5
C3
4–5
C3
C4
5–6
C4
C2
6–7
C1
C4
7–8
C4
C3
3–1
C1
C4
2–1
C3
C4
N-D
C3 – Perform garage shift adaptive learning
N-R
C5 – Perform garage shift adaptive learning
Power Downshifts
Just perform the shifts and they will adapt
Note: During low vehicle speeds with no accelerator pedal input downshift will most likely be a 3-1 shift.
To Learn C1:
Shift the transmission into 6th gear with the PRNDM in the M position. Obtain an engine speed between 1000 and 1750 rpm. Maintain this condition for a total of about
5 miles (8 km). Cruise control may be used and has been found to result in faster learning of the clutch values. Try the complaint shift to see if it has improved to an acceptable level. If not, continue with operation in this speed range until the complaint shift improves.
To Learn C2:
Note: Perform abbreviated coast down shift adaptive learning procedure listed below to enable learn mode.
Shift the transmission into 8th gear with the PRNDM in the M position. Obtain an engine speed between 1000 and 1750 rpm. Maintain this condition for a total of about 5 miles (8 km). Cruise control may be used and has been found to result in faster learning of the clutch values. Try the complaint shift to see if it has improved to an acceptable level. If not, continue with operation in this speed range until the complaint shift improves.
To Learn C3:
Note: Perform abbreviated coast down shift adaptive learning procedure listed below to enable learn mode.
Shift the transmission into 4th gear with the PRNDM in the M position. Start a slow acceleration at about 1000 rpm and maintain the slow acceleration until you reach about 1650 rpm. Once you reach 1650 rpm, go back down to 1000 rpm and repeat the slow acceleration up to 1650 rpm. Repeat this a few times and re-try the complaint shift to see if it has improved to an acceptable level. If it has not, continue this slow acceleration procedure until the complaint shift improves.
To Learn C4:
Shift the transmission into 7th gear with the PRNDM in the M position. Obtain an engine speed between 1000 and 1750 rpm. Maintain this condition for a total of about 5 miles (8 km). Cruise control may be used and has been found to result in faster
learning of the clutch values. Try the complaint shift to see if it has improved to an acceptable level. If not, continue with operation in this speed range until the complaint shift improves.
To Learn C5:
Shift the transmission into 3rd gear with the PRNDM in the M position. Start a slow acceleration at about 1000 rpm and maintain the slow acceleration until you reach about 2500 rpm. Once you reach 2500 rpm, go back down to 1000 rpm and repeat the slow acceleration up to 2500 rpm. Repeat this a few times and re-try the complaint shift to see if it has improved to an acceptable level. If it has not, continue this slow acceleration procedure until the complaint shift improves.
Abbreviated Coast Down Shift Adaptive Learning:
Lightly accelerate to 65 mph (105 km/h) and coast to 25 mph (40 km/h) (light braking can be applied). Repeat 10 times.
This procedure will enable clutch apply adaptive learning for the C2 and C3.
Note: This only needs to be performed once per drive cycle to enable the adaptive learning for all subsequent C2 and C3 learning maneuvers. Failure to perform this procedure will result in no learning of these clutches.
Power Downshift Adaptive Learning:
Starting with the vehicle operation in 8th gear, slowly apply pressure to the accelerator pedal until downshift occurs. Repeat as necessary in each gear (8, 7, 6, 5, 4, 3 and 2).
This procedure will learn the off-going clutch adapts for desired power downshift control.
Garage Shift Adaptive Learning:
Perform abbreviated coast down shift adaptive learning procedure. Then with the vehicle at a stop, hold foot on brake pedal and move the shifter from Neutral to Drive and Neutral to Reverse. Repeat as necessary until desired shift quality is achieved.
This procedure will learn the C13567 (C3-Drive) and C45678R (C5 – Reverse) oncoming clutch adapts.
4063779
14-07-30-001C
01.27.2015
Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts – 2015 GM Vehicles
BY VITALY
ON JANUARY 27, 2015
IN 2015, CADILLAC, CHEVROLET, CORVETTE, DIAGNOSTIC TIPS, ESCALADE, GMC, SIERRA, SILVERADO, TRANSMISSION, YUKON
Information on Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts – (Jan 27, 2015)
Subject:
Information on Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts
Models:
2015 Cadillac Escalade, Escalade ESV
2015 Chevrolet Corvette, Silverado
2015 GMC Sierra, Yukon, Yukon XL
Equipped with 8L90 Automatic Transmission (RPO M5U)
Attention:
This Bulletin also applies to any of the above models that may be Export vehicles.
Some customers may comment on low mileage vehicles with automatic transmission that shift feel to be too firm (harsh) or may slip or flare. Customers should be advised that the transmission makes use of an adaptive function that will help to refine the shift feel while driving and improve shift quality.
Transmission Adaptive Functions
The Hydra-Matic® 8-Speed RWD transmission utilizes a line pressure control system during upshifts to compensate for new transmission build variation as well as the normal wear of transmission components. The variation experience on a new and normal wear of the apply components within the transmission over time can cause shift time (the time required to apply a clutch) to be longer or shorter than desired.
In order to compensate for these changes, the transmission control module (TCM) adjusts the pressure commands to the various pressure control (PC) solenoids to maintain the originally calibrated shift timing. The automatic adjusting process is referred to as “adaptive learning” and it is used to ensure consistent shift feel plus increase transmission durability.
The TCM monitors the A/T input speed sensor (ISS) and the A/T output speed sensor (OSS) during commanded shifts to determine if a shift is occurring too fast (harsh) or too slow (soft) and adjusts the corresponding PC solenoid signal to maintain the set shift feel. The purpose of the adapt function is to automatically compensate the shift quality for the various vehicle shift control systems. The adapt function is a continuous process that will help to maintain optimal shift quality throughout the life of the vehicle.
How to Adapt Your Transmission
Transmission adapts can be reset and relearned on most vehicles through GDS 2 by using the Transmission Adaptive Values Learn procedure. This procedure is completed in the service stall and no vehicle driving is required.
To complete the Transmission Adaptive Values Learn procedure enter GDS 2 Diagnosis and navigate to:
Module diagnostics
Transmission Control Module
Configuration / Reset Function
Transmission Adaptive Values Learn
Transmission Adaptive Values Learn is the recommended method to reset and relearn the adapts. This procedure is available on all trucks. This procedure is also available on Corvettes built on September 29, 2014 or later. Use the Investigate Vehicle History (IVH) to verify the build date of a Corvette.
Important: Transmission Adaptive Values Learn is shown as an available GDS 2 procedure on all 2015 Corvettes built before September 29, 2014. This method is not effective and will not reset and relearn the adapts. These cars must be driven to learn the adapts.
For Corvettes built before September 29, 2014 the Hydra-Matic® 8-Speed RWD transmission adaptive learn process can only be accomplished by driving in the following manner. Execute the steps below with the vehicle warmed up on a smooth level road. The driver may observe a brief pulse behavior or firm shift feel while the transmission is optimizing the clutch learn characteristics.
Perform a test drive and note any soft or harsh shifts.
To improve these complaint shifts, locate the clutches that need to be learned in the following table below, and perform the required learning procedure for each clutch listed below the chart.
Note: The transmission fluid temperature must be between 75°C (167°F) and 85°C (185°F) during the drive procedure or adapts will not be learned.
To Correct The Shift Feel
Learn These Clutches
Applying Clutch
Releasing Clutch
1–2
C4
C3
2–3
C3
C1
3–4
C5
C3
4–5
C3
C4
5–6
C4
C2
6–7
C1
C4
7–8
C4
C3
3–1
C1
C4
2–1
C3
C4
N-D
C3 – Perform garage shift adaptive learning
N-R
C5 – Perform garage shift adaptive learning
Power Downshifts
Just perform the shifts and they will adapt
Note: During low vehicle speeds with no accelerator pedal input downshift will most likely be a 3-1 shift.
To Learn C1:
Shift the transmission into 6th gear with the PRNDM in the M position. Obtain an engine speed between 1000 and 1750 rpm. Maintain this condition for a total of about
5 miles (8 km). Cruise control may be used and has been found to result in faster learning of the clutch values. Try the complaint shift to see if it has improved to an acceptable level. If not, continue with operation in this speed range until the complaint shift improves.
To Learn C2:
Note: Perform abbreviated coast down shift adaptive learning procedure listed below to enable learn mode.
Shift the transmission into 8th gear with the PRNDM in the M position. Obtain an engine speed between 1000 and 1750 rpm. Maintain this condition for a total of about 5 miles (8 km). Cruise control may be used and has been found to result in faster learning of the clutch values. Try the complaint shift to see if it has improved to an acceptable level. If not, continue with operation in this speed range until the complaint shift improves.
To Learn C3:
Note: Perform abbreviated coast down shift adaptive learning procedure listed below to enable learn mode.
Shift the transmission into 4th gear with the PRNDM in the M position. Start a slow acceleration at about 1000 rpm and maintain the slow acceleration until you reach about 1650 rpm. Once you reach 1650 rpm, go back down to 1000 rpm and repeat the slow acceleration up to 1650 rpm. Repeat this a few times and re-try the complaint shift to see if it has improved to an acceptable level. If it has not, continue this slow acceleration procedure until the complaint shift improves.
To Learn C4:
Shift the transmission into 7th gear with the PRNDM in the M position. Obtain an engine speed between 1000 and 1750 rpm. Maintain this condition for a total of about 5 miles (8 km). Cruise control may be used and has been found to result in faster
learning of the clutch values. Try the complaint shift to see if it has improved to an acceptable level. If not, continue with operation in this speed range until the complaint shift improves.
To Learn C5:
Shift the transmission into 3rd gear with the PRNDM in the M position. Start a slow acceleration at about 1000 rpm and maintain the slow acceleration until you reach about 2500 rpm. Once you reach 2500 rpm, go back down to 1000 rpm and repeat the slow acceleration up to 2500 rpm. Repeat this a few times and re-try the complaint shift to see if it has improved to an acceptable level. If it has not, continue this slow acceleration procedure until the complaint shift improves.
Abbreviated Coast Down Shift Adaptive Learning:
Lightly accelerate to 65 mph (105 km/h) and coast to 25 mph (40 km/h) (light braking can be applied). Repeat 10 times.
This procedure will enable clutch apply adaptive learning for the C2 and C3.
Note: This only needs to be performed once per drive cycle to enable the adaptive learning for all subsequent C2 and C3 learning maneuvers. Failure to perform this procedure will result in no learning of these clutches.
Power Downshift Adaptive Learning:
Starting with the vehicle operation in 8th gear, slowly apply pressure to the accelerator pedal until downshift occurs. Repeat as necessary in each gear (8, 7, 6, 5, 4, 3 and 2).
This procedure will learn the off-going clutch adapts for desired power downshift control.
Garage Shift Adaptive Learning:
Perform abbreviated coast down shift adaptive learning procedure. Then with the vehicle at a stop, hold foot on brake pedal and move the shifter from Neutral to Drive and Neutral to Reverse. Repeat as necessary until desired shift quality is achieved.
This procedure will learn the C13567 (C3-Drive) and C45678R (C5 – Reverse) oncoming clutch adapts.
4063779
14-07-30-001C
01.27.2015
When mine starts giving me grief ..it's going ! Life is way too short for me to be going back to my highschool days ...playing around with junk cars ....
Racer
Joined: Nov 2015
Posts: 451
Likes: 181
From: Stuart FL
Thread Starter
Le Mans Master
Joined: Sep 2012
Posts: 7,146
Likes: 1,940
From: Hagerstown MD
St. Jude Donor '15-'16,'18