Trans update…
Thread Starter
Advanced
Joined: May 2014
Posts: 52
Likes: 20
Trans update…
2021 13K miles drove to dealership for oil change. Service writer says, your car has a trans “recall”. I asked if it was TSB for some ‘21 VIN with no issues or CEL’s related to emissions test ? Says no clues….Oil changed, installed new trans software and now its shifting like crap ! Going from N to D or N to M it clunks hard into first gear and almost stalls.
What do you guys/gals think ?
What do you guys/gals think ?
Popular Reply
Apr 8, 2024, 11:11 AM
Melting Slicks
Joined: Feb 2023
Posts: 2,368
Likes: 2,495
From: Northern Virginia
2023 C8 of the Year Finalist - Unmodified
make a 180 and take it right back to them.....
Pro
Joined: Sep 2005
Posts: 672
Likes: 849
From: DFW
2021 13K miles drove to dealership for oil change. Service writer says, your car has a trans “recall”. I asked if it was TSB for some ‘21 VIN with no issues or CEL’s related to emissions test ? Says no clues….Oil changed, installed new trans software and now its shifting like crap ! Going from N to D or N to M it clunks hard into first gear and almost stalls.
What do you guys/gals think ?
What do you guys/gals think ?
Poor choice of words on behalf of your service writer. I'm sure it was a TSB, as recalls are government mandated and safety/emissions related generally speaking. I SUSPECT that your DTC is relearning your driving style/manner and should be back to normal (or better) after several drives in your C8.
Drifting
Joined: Mar 2017
Posts: 1,923
Likes: 2,029
From: Columbus OH
2021 13K miles drove to dealership for oil change. Service writer says, your car has a trans “recall”. I asked if it was TSB for some ‘21 VIN with no issues or CEL’s related to emissions test ? Says no clues….Oil changed, installed new trans software and now its shifting like crap ! Going from N to D or N to M it clunks hard into first gear and almost stalls.
What do you guys/gals think ?
What do you guys/gals think ?
Before Thursday, my transmission would shift pretty hard from first to second gear in manual mode if the shift didn't occur at the proper RPM. I found the hard shift rather obnoxious and it has been my biggest gripe about the C8's DCT. After the software update, it's a different transmission. It now shifts so smoothly between first and second gear at any RPM that the only way I know it shifts is by the gear display on the DIC. All the other gears shift just as smoothly. When other owners would say their DCT would shift as smooth as butter, I would scratch my head in disbelief because mine certainly didn't behave that way. After the update, I now have to say the same thing.
CF Community Team
Joined: Nov 2005
Posts: 5,217
Likes: 2,868
From: Charlotte N.C.
When I got my used 2020 dealer said there were no outstanding recalls then I took it in for an oil change and the local dealer said there were four "recalls" but then admitted they were bulletins. Two had expired and one of the two they did was a DCT reprogram.
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Melting Slicks
Joined: Jan 2009
Posts: 2,339
Likes: 2,613
From: Covington LA
They did a update on my 21 C8 transmission during my 1st oil change and mine shifted like crap for about a day. I kept driving it around and the next day smooth as butter and has been ever since.
Race Director
Joined: Mar 2001
Posts: 19,947
Likes: 6,748
From: Bonneville Salt Flats
One would think that if it is going to take time/driving/hoping/incantations or whatever to eventually work correctly, the dealer would be instructed to tell the owner or better yet give each a notice with the expectations/procedures, the same as a physician does when one has a procedure completed. It's not like they all aren't making enough along the way to do so. Good grief! 
Race Director
Joined: Jan 2014
Posts: 10,709
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From: Fulshear, TX
I suspect cars with higher miles/more wear on the clutches will experience more of a dramatic change in shift quality immediately after the reflash. It should smooth out again as it relearns with driving, but the dealer really should be performing the quick learn procedure for you. My 2021 is due for this reflash and will be completed along with my 3 year DCT fluid & filter job. If the dealer doesn't do it for me, I'll run a quick learn procedure as soon as I get my car back (it'll be around 22k miles at the time). I do experience the phantom codes when I run a scan.
Thread Starter
Advanced
Joined: May 2014
Posts: 52
Likes: 20
Thanks guys for sharing. Service called say the tech now found a “code downshifting” seriously ?
no ECL none for 3 years, update trans software now shifts like a dump truck and throws code ?
you can’t make this stuff up. Service writer says all their techs are Corvette certified…
no ECL none for 3 years, update trans software now shifts like a dump truck and throws code ?
you can’t make this stuff up. Service writer says all their techs are Corvette certified…
Thread Starter
Advanced
Joined: May 2014
Posts: 52
Likes: 20
I suspect cars with higher miles/more wear on the clutches will experience more of a dramatic change in shift quality immediately after the reflash. It should smooth out again as it relearns with driving, but the dealer really should be performing the quick learn procedure for you. My 2021 is due for this reflash and will be completed along with my 3 year DCT fluid & filter job. If the dealer doesn't do it for me, I'll run a quick learn procedure as soon as I get my car back (it'll be around 22k miles at the time). I do experience the phantom codes when I run a scan.
thanks Kracka ! How do you do the quick learn ?
Race Director
Joined: Jan 2014
Posts: 10,709
Likes: 7,101
From: Fulshear, TX
You need a bi-directional scan tool. I use the Launch Creader Elite X431:
Your code could be a leftover stored code from before the reflash, but who knows... They should clear all codes and run the necessary procedures. Unfortunately, cars have become rolling computers so software, updates, etc. don't always go as planned. I just wish they would update them as quickly as we're used to with our cell phones (running modern processors from this decade wouldn't hurt either).
Your code could be a leftover stored code from before the reflash, but who knows... They should clear all codes and run the necessary procedures. Unfortunately, cars have become rolling computers so software, updates, etc. don't always go as planned. I just wish they would update them as quickly as we're used to with our cell phones (running modern processors from this decade wouldn't hurt either).
CF Community Team
Joined: Nov 2005
Posts: 5,217
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From: Charlotte N.C.
I really hate to say it but from my last few years of visits to Chevrolet service, I don't trust the service manager or writer to tell me the truth or what was really done. I don't expect the writer to understand my problem or how a car works. I don't trust the mechanic to do all the step of a procedure, to even do what is supposed to be done or to do what I'm billed for. I'm on the fence if they actually swapped a part I'm billed for or used genuine GM parts or fluids.
This opinion has been formed over the last few years and over a couple different Corvettes, I don't own any other GM vehicles. I am trusting of the service departments for the other vehicles we own.
I also don't trust any sales person, manager or finance/ paper work person and that bleeds over to other brands. I feel all you are is a mark to them and how much can they wring out of you before you'll go elsewhere.
It really pains me to say it. I have such a bad feeling about one dealership, just a couple miles from my house that I wanted to look at a new 2024 in the colors and optioned in a way I would consider and I made a point to ride one of my motorcycles in to look at it and avoided the sales guy. They do look at you differently coming in on a bike.
This opinion has been formed over the last few years and over a couple different Corvettes, I don't own any other GM vehicles. I am trusting of the service departments for the other vehicles we own.
I also don't trust any sales person, manager or finance/ paper work person and that bleeds over to other brands. I feel all you are is a mark to them and how much can they wring out of you before you'll go elsewhere.
It really pains me to say it. I have such a bad feeling about one dealership, just a couple miles from my house that I wanted to look at a new 2024 in the colors and optioned in a way I would consider and I made a point to ride one of my motorcycles in to look at it and avoided the sales guy. They do look at you differently coming in on a bike.