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I apologize if this has been asked before, but does anybody else have trouble with automatic downshifting from higher gears? I've noticed a bunch of times that I'll be in 7th or 8th gear and when I stomp on the gas nothing happens (except for slight increase in speed, of course). No downshift at all. This happens in normal mode or Z mode. Yesterday I was on the expressway doing 70 in 8th gear and tried to pass somebody fairly quickly. No downshift. So I watched the RPM once I manually downshifted to get around him. Under 2000 RPM in 7th or 8th gear there was no automatic downshift. Is this normal? Is there something I'm doing wrong?
No, that is not normal. I drive mostly in Tour mode and MyMode (with engine/shifting set to Tour). It always downshifts when I step on the gas, even when doing 80 on the freeway in 8th gear..
"Like other transmissions, the TR9080 has adaptive learning capabilities. The TCM/DCT may need to be re-calibrated based on what it has learned, or for other reasons, hardware changes, etc. The process requires the use of a quality scan tool and is very similar to other applications. On this application, the process is displayed on your scan tool, so it is as simple as following the steps displayed. Keep in mind, like other applications, you must achieve the correct transmission fluid temperature for the fast-learn process to function. (140-212 °F, 60-100 °C)"
Quick question for all that are having issues with their C8's that require multiple weeks in the shop. Do they provide you a loaner/courtesy car? I cannot imagine some folks being able to go for weeks+ with no car. Wonder if there are mixed results too based on dealer. Also not expecting another C8 as a loaner, assume would be a Malibu/Equinox/Colorado or the like equivalent. Our GMC dealer provides the Terrain/Enclave but they will not work on Corvette's when I asked one of the service tech's.
I was offered one. Thanked them and declined as I didn’t need it.
I was offered one. Thanked them and declined as I didn’t need it.
Thanks @EASonBASS Normally I decline a loaner also as I am lucky enough to have an extra car, but it has also come in handy at times. My Chevy dealer did not have loaners there for better part of 2 years just due to all the madness we have experienced. Appreciate the response.
P0700 , P0844
Got idle creep temporarily disabled and would only shift in even gears. Turned around the second I saw it and only was about a half mile from home. On restarting, it crawls fine and all gears seem to be working. CEL is still on. Have made an appointment with the local dealer. Anybody have knowledge with P0844? I've been unable to find a significant amount of information on the code and even less positive resolution. I know P0700 seems to just be a "turn the CEL on" code. Hoping it doesn't end up being a major issue.
P0700 , P0844
Got idle creep temporarily disabled and would only shift in even gears. Turned around the second I saw it and only was about a half mile from home. On restarting, it crawls fine and all gears seem to be working. CEL is still on. Have made an appointment with the local dealer. Anybody have knowledge with P0844? I've been unable to find a significant amount of information on the code and even less positive resolution. I know P0700 seems to just be a "turn the CEL on" code. Hoping it doesn't end up being a major issue.
I don’t recall my exact codes, but I got the idle creep message, CEL, and shifting problems you describe. After sitting at home it might run okay for a mile or or two, but then get worse.
In my case, GM procedure was to flush the system. That didn’t work so next step was valve body replacement. That didn’t work and the transmission is currently being replaced.
That’s not to suggest you will need a new tranny. The cause and solution for this seems to vary greatly. I’ve read of situations where the simple system flush solved the issue. I’m hoping yours is a simple one.
(edited to fix some typos... things get funky when typing on an iPad)
As I was pulling into my driveway and putting my top up the tonneau cover opened and I received the “service convertible top” message. Now the tonneau cover is in the full upright position and will not close. I tried disconnecting the battery and re-indexed the side wide windows. The “service convertible top” message is no longer displayed, but the top does nothing. Same thing for the rear window. Nothing.
Since the tonneau cover is fully upright I did not want to drive the car to the dealership, but If I have a tow truck driver come it would not be any different if they are driving my car on the back of their flat bed truck with the top fully open. Maybe even worse if they don't maintain their speed less than 30 mph. I am waiting for the dealer to call me back. I think I will drive the car to the dealer (~5 miles) early in the morning, unless the dealer or someone here on the forum has a better idea.
Car is a 2022 with 1200 miles.
If you do, I want to get a video of that. My 2008 MX5 Miata has a Power Retracting Hardtop that has been up and down hundreds, if not thousands of times over the years and has never had an issue other than with a Smarttop module's cable connector (aftermarket device that allows the top to be opened or closed at up to 30 MPH), but that had nothing to do with the OEM module.
After owning Corvettes for more than 30 years, I am not surprised at all at the thousands of problems the C8s are having. I learned my lesson, long ago but it's sad that the same cycle of frustration continues to happen for so many others.
Had the DCT replaced in May '22 at 4,700 miles (MY '21). New leak discovered today at 6,200 miles. Only found it as I was parked on an incline and it dripped off the belly pan.
1st DCT took nearly 2 months to get diagnosed/approved by GM engineers and finally replaced. Goes in Monday.
Let's just say I'm in the Not Happy category at the moment.
Had the DCT replaced in May '22 at 4,700 miles (MY '21). New leak discovered today at 6,200 miles. Only found it as I was parked on an incline and it dripped off the belly pan.
1st DCT took nearly 2 months to get diagnosed/approved by GM engineers and finally replaced. Goes in Monday.
Let's just say I'm in the Not Happy category at the moment.
Hopefully it's a gasket and not a porous casting. If you have the coupe, you can open the trunk and, with a flash light and a bit of a stretch, you can see down and see the "usual" porous area. The area is just behind the drive shaft boss and the sheet metal safety cover.
I keep saying that it is ridiculous to not have a dipstick or some easy way to check oil level on a 20,000$ transmission. Even a low oil sensor- heaven forbid we need another sensor. Other forum members tell the trans is a “factory permanently sealed unit” and doesn’t need to be checked but many have leaks. You have no idea how much fluid you loose because it could be blowing back on hot exhaust system. My 90k car with a 20k transmission and no way to check trans level- just so silly…
I keep saying that it is ridiculous to not have a dipstick or some easy way to check oil level on a 20,000$ transmission. Even a low oil sensor- heaven forbid we need another sensor. Other forum members tell the trans is a “factory permanently sealed unit” and doesn’t need to be checked but many have leaks. You have no idea how much fluid you loose because it could be blowing back on hot exhaust system. My 90k car with a 20k transmission and no way to check trans level- just so silly…
Hopefully it's a gasket and not a porous casting. If you have the coupe, you can open the trunk and, with a flash light and a bit of a stretch, you can see down and see the "usual" porous area. The area is just behind the drive shaft boss and the sheet metal safety cover.
Its a HTC. This time leak is on the left though so possible culprit.
To clarify I meant an easy way to check oil level. without putting car on lift removing belly pan etc. I mean preventive maintenance a layman could check his oil level not a mechanic or now I guess they call them technicians….
To clarify I meant an easy way to check oil level. without putting car on lift removing belly pan etc. I mean preventive maintenance a layman could check his oil level not a mechanic or now I guess they call them technicians….
The fluid level on a manual transmission is typically checked by lifting the vehicle and removing a plug from underneath the vehicle. The C8 isn't much different other than it needs to have a plate removed and be at the proper operating temperature. This is simple compared to some other cars with DCTs which require a computer to check the fluid level.
Adding the cost of having a dipstick doesn't justify the need. If the transmission isn't leaking the level won't get lower. Notice that the fist sign of a leak was people saw it before the level got low enough to cause any problems. This transmission holds 11 quarts of fluid. Loosing a pint of fluid won't cause any operational problems but it sure would be noticed even if leaked over several thousand miles. You would see spots on the garage floor, notice oil on the back of the car, and probably smell it. It doesn't take much oil to cause a mess. The only way it would get too low is if you ignored the signs.
The fluid level on a manual transmission is typically checked by lifting the vehicle and removing a plug from underneath the vehicle. The C8 isn't much different other than it needs to have a plate removed and be at the proper operating temperature. This is simple compared to some other cars with DCTs which require a computer to check the fluid level.
Adding the cost of having a dipstick doesn't justify the need. If the transmission isn't leaking the level won't get lower. Notice that the fist sign of a leak was people saw it before the level got low enough to cause any problems. This transmission holds 11 quarts of fluid. Loosing a pint of fluid won't cause any operational problems but it sure would be noticed even if leaked over several thousand miles. You would see spots on the garage floor, notice oil on the back of the car, and probably smell it. It doesn't take much oil to cause a mess. The only way it would get too low is if you ignored the signs.
I think the DCT is very much different from the typical manual transmission. It is literally the entire drive train consisting of the clutch, trans and differential all in one oil bath. Having no simple way to monitor/ check the fluid level is silly. Particularly as the car ages and some of the new cars are already having leak problems.
Has anyone seen this yet? Shorn engine shielding on right side just shy of 700 miles. Car runs fine. Was driven properly and in accordance with manual’s recommendation during 500 mile break in. Left side photo for reference to show damage.
My 2008 MX5 Miata has a Power Retracting Hardtop that has been up and down hundreds, if not thousands of times over the years and has never had an issue other than with a Smarttop module's cable connector (aftermarket device that allows the top to be opened or closed at up to 30 MPH), but that had nothing to do with the OEM module.
