C7 AFM / Transmission issues.

[Norm]

Tried to purchase Range AFM from ebay off ivasoare6 two weeks ago. Never received it and no reply
from emails sent.... bewhere!
Will have to go to the states for one unless anyone knows a supplier in the UK??

I would deal directly with Range, don't look for the deal, sometimes it's not worth the aggravation if something goes wrong. And besides, by buying direct, you'll be registered with them. Range has a very good return policy, if the device needs an upgrade, they will either replace or upgrade free, you pay shipping though.

AFM/DFM Disabler - Range Technology

AFM Disabler and DFM Disabler for GM car, truck and suv

rangetechnology.com

 

[Norm]

Norm - Thanks for the fuse location/number. As regards switching the exhaust I didn't mean the mode selector knob on the centre console which changes a number of other parameters at the same time. I meant the engine sound menu in the centre screen which changes the exhaust sound separately from anything else. I've heard it said that even in Loud mode the valves close some of the time, but have no evidence to back that up.

Paulus - It's my understanding that Keith Beschi at Eurovettes would be able to supply.

OK, I got it now. I believe once the fuse is pulled, that loud/quiet mode function from the screen is inoperative, just give it a test while on the road, you'll find out there shouldn't be a change.

 

[Norm]

Short and sweet, if you have an automatic, you will get the most use from the Range Disabler.
If you have a stick, the Range will disable the 4 cylinder mode in ECO. With a stick, your NPP exhaust flaps should stay open in all the other driving modes.

 

[Paulus]

Cheers Stingray!

 

[RogerH]

I have an A8 2017 C7 Grand Sport here in New Zealand and presumably face the same issues you do in the UK with no dealer support.
In the US the C7 A8 transmission shudder is a big topic with class action (unfortunately unsuccessful) launched against GM over the matter.
My C7 (which I have had since new) has done 6000 miles and showed the first hint of the shudder at a steady speed of around 100kph. Initially I tried a dose of LubeGard Platinum to the transmission fluid but this didn't seem to work. I then installed a Range AFM delete which turns off the 4 cylinder function - while this made the car more pleasant to drive the shudder was still evident.
The only solution seemed to be replacing all the existing transmission fluid with the new improved Mobil blue label fluid on the basis that the fluid used before January 2019 was hydroscopic and the moisture content was causing the shudder. This process is done under warranty in the US with a special GM flush machine giving a triple flush of 24 quarts to achieve sufficient replacement with the new ATF.
The problem was that GM in NZ did not have the either the flush machine, the new Mobil blue label fluid, a new transmission sump gasket or transmission filter. Thankfully Mobil NZ imported 24 quarts of the blued label fluid for me and I got the filter and sump gasket through Amazon.
I had to do the flush manually on the hoist with a series of 6 pumping out of transmission fluid and replacing it with new. This eventuated with about a 93% new fluid content and has fixed the problem.
If anyone is interested I can go through the process I used as there are "tricks" that I learnt during the process. It is not that difficult but a bit time consuming and I think the only way to properly resolve the shudder issue.

 

[teamzr1]

Here is the USA most owners of GM vehicles that have DOD/ADM tell me to turn that crap off within the PCM tune

The 8 speed automatic transmissions in several GM vehicles, including five model years during the C7 Corvette era, have been the subject of five separate class action lawsuits claiming defects.

Now, Michigan Judge David M. Lawson has consolidated the five suits and also dismissed two claims one for implied warranty for all plaintiffs that fall under the laws of Alabama, Arizona, Connecticut, Idaho, Kentucky, North Carolina, Tennessee, Washington, and Wisconsin & another for one plaintiff who claimed class-wide monetary damages under the Colorado Consumer Protection Act.

Judge Lawson will allow other allegations in the suit to proceed, including certain other claims related to implied warranty.
The judge also acknowledged that the complaints put forth by plaintiffs could be consistent with either materials/workmanship defects or a design defect.

He also did not dismiss claims that GM knew there were issues with the 8 speed transmission before it put affected vehicles on sale, saying “plausible inferences may be drawn that GM had substantial knowledge about the looming problems with its new transmissions before any of the plaintiffs’ purchases were made.”

The suits allege that GM’s 8L45E and 8L90 automatic transmissions can cause slipping gears, shifting into gear aggressively, shuddering or jerking, delayed acceleration, and trouble slowing down.

GM argues that because all these transmissions experience these problems, they are caused by a design defect and the suits should be dismissed because GM’s express warranty only covers defects in materials and workmanship.

Other allegations in the suit can proceed, the judge ruled, including certain other claims related to implied warranty. Lawson also noted that the complaints could be consistent with either materials/workmanship defects or a design defect.

He also allowed claims to continue that GM was aware of the transmission issues before the vehicles were sold, saying “plausible inferences may be drawn that GM had substantial knowledge about the looming problems with its new transmissions before any of the plaintiffs’ purchases were made.”

The affected Corvettes include 2015-19 models with A8

The first year of the C7 generation featured a 6 speed automatic transmission that is not included in the suits.

Other GM vehicles affected :

• 2015-2017 Cadillac Escalade
• 2015-2017 Cadillac Escalade ESV
• 2016-2019 Cadillac ATS
• 2016-2019 Cadillac ATS-V
• 2016-2019 Cadillac CTS
• 2016-2019 Cadillac CTS-V
• 2016-2019 Cadillac CT6
• 2015-2019 Chevrolet Silverado
• 2017-2019 Chevrolet Colorado
• 2016-2019 Chevrolet Camaro
• 2017-2019 GMC Canyon
• 2015-2019 GMC Sierra
• 2015-2019 GMC Yukon
• 2015-2019 GMC Yukon XL
• 2015-2017 GMC Yukon Denali
• 2015-2017 GMC Yukon Denali XL

 

[RogerH]

GM argues that because all these transmissions experience these problems, they are caused by a design defect and the suits should be dismissed because GM’s express warranty only covers defects in materials and workmanship.

It is cold comfort to Corvette owners with the 8L90 auto transmission that GM reject any obligation to remedy the problems because they are caused by "a design defect". Surely GM are responsible for the quality of the design of components used in their vehicles - fitness for purpose? But I suppose the GM lawyers say that the warranty wording only specifies workmanship and material defects ........

 

[Roscobbc]

One can only imagine what in future these problems will give to future buyers of these cars. I guess they'll end up having multiple owners as disgruntled owners offload them to perhaps unsuspecting buyers. Me? - having driven IAM's demo car when the C7 8 speeder first came out (and loved it) it was on my future bucket list.......was, perhaps not now.........

 

[RogerH]

Don't let the C7 auto issue put you off - cars after early 2019 have the correct ATF fluid and earlier ones are able to have a transmission flush to fix (and it only needs to be done once). If required the AFM delete can be easily achieved with a simple plug in Range product.
The Corvette is a great car - my first American car and is probably the most competent and easily driven of all the exotic cars I've had. When needed it can be a brute. When racing in the US a couple of years ago I saw a few C7s and was very impressed and a standard C7 Grand Sport lapped Laguna Seca quicker than a standard Ferrari F12. Photo of mine below - bought it from a US dealer but they are unable to sell new cars to non-US citizens so it land here with 126 miles on the clock as a used car!

 

[Chevrolet]

Me? - having driven IAM's demo car when the C7 8 speeder first came out (and loved it) it was on my future bucket list.......was, perhaps not now.........

Sorry Ross, but I think you may have got it wrong here? And let's not damage the reputation/market for used UK/Euro spec C7s (including mine)? My understanding is that the trans shudder problem on US C7 8 speed Autos may arise from the AFM on those cars switching the engine to 4 cylinder running in certain driving conditions. As you can see from the above, UK/Euro spec cars only run on 4 cylinders on start up in "ECO" driving mode, and if you keep it in "ECO." So all you do after starting, is switch it to Tour, Sport or Track mode to ensure the car is running in V8 all of the time.

 

[Chevrolet]

The Corvette is a great car - my first American car and is probably the most competent and easily driven of all the exotic cars I've had.

Great looking car!

 

[Roscobbc]

Sorry Ross, but I think you may have got it wrong here? And let's not damage the reputation/market for used UK/Euro spec C7s (including mine)? My understanding is that the trans shudder problem on US C7 8 speed Autos may arise from the AFM on those cars switching the engine to 4 cylinder running in certain driving conditions. As you can see from the above, UK/Euro spec cars only run on 4 cylinders on start up in "ECO" driving mode, and if you keep it in "ECO." So all you do after starting, is switch it to Tour, Sport or Track mode to ensure the car is running in V8 all of the time.

The 8 speed transmission on the C7 was undoubtedly one of its best features and always in the right gear at the right time, even skipping ratio's in certain conditions. The 'nanny' electronics controlling traction, yaw etc were so good and imperceptible, yet instantaneous in operation that you wondered if they were actually working even in the worst weather conditions - Superb.

 

[teamzr1]

If people need the GM TSB and fix process for this A8 issue
Here is the GM PDF for that

 

[Chevrolet]

Here is the GM PDF for that

Thanks for that. So flicking thru it quickly, that looks like the instructions for the "triple flush" mentioned above (see page 17 of PDF)? Or "triple drain and fill" as they call it?

 

[RogerH]

Thanks for that. So flicking thru it quickly, that looks like the instructions for the "triple flush" mentioned above (see page 17 of PDF)? Or "triple drain and fill" as they call it?

There is a slightly different process for export cars (TSB 19-NA-018) presumably because the special GM flush machines are not available. This is the process I used.

19-NA-018 Chevrolet Technical Service Bulletin

19-NA-018 Chevrolet Technical Service Bulletin

www.tsbsearch.com

 

[Corvette]

2-stroke LC350 (perhaps not !).

Respect! Had a few with Stan Stephens tune, wheel in the air on demand. Great times.

 

[Chevrolet]

There is a slightly different process for export cars (TSB 19-NA-018) presumably because the special GM flush machines are not available. This is the process I used.

Interesting. Had mine "flushed"/latest non hydroscopic fluid, as a precautionary measure, at the UK's sole Vette/Cadillac new car dealer (Ian Allan motors). Whether they have a flush machine I do not know?

 

[Vet68]

Interesting. Had mine "flushed"/latest non hydroscopic fluid, as a precautionary measure, at the UK's sole Vette/Cadillac new car dealer (Ian Allan motors). Whether they have a flush machine I do not know?

Was that under warranty or did you have to pay? My late 2018 C7 is just about still under warranty but Ian Allen would not flush unless the problem can be demonstrated. They reckon not all cars are affected.

Mine is UK spec.

 

[Chevrolet]

Was that under warranty or did you have to pay? My late 2018 C7 is just about still under warranty but Ian Allen would not flush unless the problem can be demonstrated. They reckon not all cars are affected.

Mine is UK spec.

Had to pay for it. Did Ian Allan really say that "not all cars are affected." I'd be interested to know if "any" UK spec cars have been affected? A you can see from the above, the transmission problem/shudder on US cars appears to be due to the AFM running the cars on 4 cylinders in some conditions. As UK cars only run on 4 cyclinders in ECO mode, they dont have that problem. I know four UK C7 auto owners, including myself. We dont drive the cars in ECO mode (always V8) and non of us have had a problem, albeit on our low mileage cars.

 

[Vet68]

Ian Allen did say that. I explained that I recently acquired a UK car still under warranty and wanted to know if it had been flushed, or would not be affected as it may have had the newer transmission fluid in it. They said that due to GDPR - they could not tell me if it had had a flush (under previous ownership) which sounded rather ridiculous to me. They could not tell me anything about the car or if it had the new fluid, out of the factory (September 2018 registration, I do not know when built but it is a 2019 model). I therefore pushed to ask if I could get the fluid changed as a precaution, and it was a direct 'No, not unless you have the problem, as not all cars have it'. I asked what I should look out for symptom wise but they would not tell me other than 'you will know if you have it'. They also seemed to debunk the V4 mode being a problem too. So, I am none the wiser from contacting the importer/original seller who could make a warranty claim for me, but I have to demonstrate that there is a problem before any help at all can be offered. Warranty runs out in 2 weeks time.