Has anyone experienced any type of engine sporadic acceleration at initial cold startup? When I first start my 2023 C8 Z51 HTC, and put it into gear, it is jerky, attempting to accelerate quickly/repeatedly for the first 5 to 10 minutes of driving. I'm not sure if it's an fuel injector issue, or the transmission wanting to go from the V8 to the V4 too quick. This happens even at low speeds like 20 mph. As I'm slowly moving through my neighborhood, it is very jerky, and I look down and it's showing going from V8 to V4 - even at 15-20 MPH. When I first accelerate on the highway it's very jerky as well (cold motor). Once the motor warms up after 5 or 10 minutes, no problems.

Going to take it in for service and have this issue checked but unfortunately the motor will be warm when it gets to service and I doubt it will replicate it when there. Hoping someone else might have experienced this and can give me an idea of what to tell the technician as far as a potentially pinpointing the issue.

Thanks to all!

 

I have an ERay and when I cold start the car when leaving the neighborhood, I get what you're describing for about 1 min or until the idle backs down to normal.

 

Wait the 90 seconds it takes to let the idle drop. Then see if it is still a problem.

 

I have waited 3 - 5 minutes and still does it. Hoping the service tech can replicate it and adjust it electronically. Could be set too lean but we will see.

Thanks to you and the other response.

 

I hope they can the problem fixed; I just don't like the idea of they will want to keep it overnight. I think the dct just needs to have the fast learn procedure. MORE Attachment - CorvetteForum - Chevrolet Corvette Forum Discussion - Transmission Service Fast Learn PDF

 

Be sure to let us know what you find out.

 

Service scheduled for 6/24. Will update after that.

Thanks.

 

Late on this reply but here's what I learned at the first dealer. They could not replicate the transmission issue. They serviced the vehicle and then told me that their Corvette expert was not the one that looked at the vehicle even after they told me the person would be the one. Basically I got a young nobody who provided an oil change and didn't do much of anything else. Stayed there 6 hours to be told the expert never looked at it. Of course, I drove 3 hours to Hendrix Chevrolet in Cary, North Carolina, the Corvette experts. Highly disappointed.

The cold crank issue has persisted for the last month so I contacted the selling dealer and had a very good discussion with their lead technician. He said there have been a lot of problems with the transmission and valve body. Apparently many of the Z51s are having issues. They first start working through with your basic transmission flush, then replacing the valve body, and on many occasions have had to replace the entire transmissions. I had seen several references on this forum since I made my initial post. There are many owners who are having the same problems. I have since Googled C8 transmission problems and gotten a lot of other sites where Corvette owners have been blogging information and everybody is encountering the same problems. It could happen at 500 Miles 5,000 miles or 15,000 miles.

apparently in a lot of cases, after the transmission valve body has been replaced, the problems have resolved on some occasions they've actually had to go back and replace the actual transmission. I am hoping mine is going to be simple and maybe a transmission flush will solve it or the valve body being replaced will solve it. Needless to say I'm highly disappointed. This is the most I've ever paid for any vehicle and to see it have this many problems in its third year is very disappointing as well. I have a 2023 hardtop convertible Z51. I purchased it from a dealer as a certified pre-owned vehicle, that only had a little over 14,000 miles when I purchased it in 2025. It now has close to 18,000. I've had it for exactly one year. Luckily, all of the previous service was done by the selling dealer and they have all of the records. Since it is certified pre-owned, I'm not too concerned but as we all know, we hate to have major service performed on something that's basically brand new.

Sigh.....

 

The only procedure for the transmission that uses the term "flush" is a hydraulic system flush. It is an 8 minute procedure, activated by a scan tool while the car is on the ground with the engine running and foot on the brake, that actuates the valves in a specific manner with a goal of releasing debris - that will be moved to the external canister filter. And sometimes it does resolve a problem. There are many forum reports of that. That procedure is also step 1 of the procedure for replacing the external canister filter, so it should be performed every time the filter is changed if the dealer does it properly (or if DIY if you have the necessary scan tool). There is no other flush procedure - the transmission fluid replacement procedure is not called a flush, and does not require the HSF. However, transmission fluid replacement is another remedy that is tried in many of the transmission related diagnostic procedures, and that too might resolve an issue. Some of the diagnostic procedures even call for replacement of the internal filter in an attempt to resolve an issue. I don't know if that has ever worked though.

When I say diagnostic procedures, I am referring to procedures that have been pointed to by a DTC, and the process is to try a remedy, clear the DTC, and see if it returns. If it goes away the problem is assumed to be resolved. If it returns, the next remedy is tried. If all remedies fail, then it calls for (typically) replacement of a valve body, some other component, or the transmission. Without a DTC its more difficult - but I don't see why those same remedies could not be tried - as a shot in the dark.

 

Just an idea.

I had my Cold Start and AFM/V4 deleted during my E85 tune. Enjoy not having the mandatory Cold Start plus the extra 40 rwhp / 30 wtq and clean burn is nice.

Looks like E85 is pretty available in North Carolina.

If you like you can PM me on details, questions or concerns.

 

FWIT, my 2020 C8 was the same as my 18 month old E-Ray, no issue pulling away from my home, no jerky motion. And in 2 miles on our twisty narrow road to a highway going 30 to 35 mph, zero jerky feeling. Than although I would like the engine and oil to be at temp I have to make a right hand turn and merge onto a 4 lane divided highway with most traffic going ~70 mph on a 60 mph limit. Zero Jerky feeling and generall lift a bit so it shifts at about 4500 rpm.

 

My car went to the selling dealer today The service technician started it cold this morning and drove it. It shuddered and jerked like crazy. He was definitely concerned it might be transmission related but also thought it could be something wrong with the motor and the tuning.

After an hour searching different technical bulletins from GM and Chevrolet, he found the following Bulletin: 22-NA-080, Issued April 2022.

The bulletin involves a sticking Camshaft Actuator Magnet. The bulletin involved Corvettes, Chevrolet and GM trucks, and Cadillacs as well as other GM products involving the LT1 and LT2 engines produced between 2014 and 2022. My Corvette is a 2023 Stingray Z51 HTC.

Additional search found an update issued 5 days ago! They have now extended the vehicles to include all of those built with the engines up through 2025!

If the camshaft magnet is out of balance by 4 degrees or more, it has to be replaced. There is a test they conduct to determine it. Mine was out by more than than four degrees The magnet will have to be replaced. The engine will have to be dropped to do so! Parts have been ordered. It takes over 2 days to complete the service work, then they have to test the car to make sure it is operating properly. In other words, it will be in the shop at least one week.

Here are 2 links:

https://www.corvetteforum.com/forums...209d1654289877

https://www.midenginecorvetteforum.c...ne-shudder-fix

I guess we will see if this solves the problem. I am more concerned that there may be hidden engine damage that may not show itself for a while.