PaulCPO

'23 HTC. just over 1000 miles.

I have pulled up to a stop sign on a slight hill and when I give the car some gas nothing happens and then all of the sudden the transmission engages suddenly and harshly. It's like I had the car in neutral and then shifted to drive suddenly.

This has happened twice now - one time in M and one time in D. Fairly isolated incident so reluctant to go to dealer now as it is unlikely the condition can be repeated.

Anyone else have this issue? Suggestions?

Phil1098

Mine did that after a fluid change, I added the two extra quarts and it never happened again. Have them check the fluid level.

PaulCPO

Thank you. That's what I was thinking. I have to take it in to get the map light fixed anyway. Is there any reason why having the 2 extra quarts is a bad thing if you are not tracking?

budgreen3564

Hill assist

RKCRLR

@PaulCPO , were you stopped on an incline when your issue happened?

LucaBrasiAZ

sounds like hill assist to me...sometimes its jerky when throttle is applied and it releases.

Phil1098

Doesn't hurt a thing, but the others are probably right with the hill assist, in the land of the flat I never experienced it.

RKCRLR

Some of the later 2023's (I think the cutoff date is somewhere in mid-July) have the newer DCTs that don't require the additional 2 quarts for tracking. It shouldn't hurt anything if it is added to the later DCT and your manual probably tells you to do it if tracking (although technically if you have a non-Z51 you shouldn't be tracking in GM's eyes). The 2024s do not require (nor authorize) the additional 2 quarts.

Phil1098

When I talked to Josh Holder at the Bash he said Z06 had the new case design (internal baffles to prevent slosh) and the 2024 cars would have it also. Maybe they started early and late 2023 SR has the new case too.

RKCRLR

According to Harlan it was incorporated on July 14:
https://www.corvetteforum.com/forums...24-design.html

Phil1098

Good to know, I talked to Josh in April so they moved up the plan.

PaulCPO

eels very unnatural.
Yes. Slight incline.
Again. Very Bam.

Me neither. Only on a hill.

It's a Z51 with a build date of 7-27

7-27 build date.

Andybump

The name of that feature in your owners manaul is "Hill Start Assist". If you are stopped on a slight incline, either direction the car will apply the regular brakes to prevent it from rolling during transition from the foot brake to the throttle. If that conditions persists for a few minutes, the car will actually then apply the EPB. Either way, when you first step on the throttle, there may a a lack of smoothness as the car tries to accelerate before the brakes are fully released. If you have downloaded a copy of your 2023 Owners Manual, search on Hill Start Assist.

PaulCPO

I have felt that before. This is different. Best way to describe it is like you have the car in neutral, rev the motor slightly and suddenly put the car in drive. Very harsh.

Andybump

ok.

rocsvette

My driveway has a slight incline and if I pause before driving into the garage, I get that lurch. It’s from hill assist as others said. And my DCT has the extra 2 qts of fluid.

Fast Dawg

I have three GM vehicles - a 2020 Silverado, a 2020 Yukon Denali, and a 2021 C8. All three vehicles have hill assist. I live in a rural area where there are a lot of inclines at stop signs and traffic lights where they all engage hill assist. My C8 is the only car that gives me the sensation you describe and I attribute it to the DCT. No issues with it at all.