Kev4

Is there a way to tell when the A8 transmission is in V4 mode with an icon etc? Also does it go into this mode only when in 8th gear or in all gears depending on your pedal pressure?

hangman

JaxC7

It goes into V4 pretty much any time you're moving without a load on the engine (i.e. - constant speed cruising). I know the indicator is displayed on the range/average fuel economy DIC info screen, but not sure where else.

lakemg

True except for when you're in Manual (paddle shift) mode, it stays in V8 full time...

JaxC7

Good catch. I forgot to mention that.

bsterling9

There is a lot of confusion surrounding this cylinder deactivation process and the dealers are all but worthless. I asked TWO dealers the following simple question: Does the cylinder deactivation occur in ALL modes or just ECO? They had no clue. From owner feedback on this forum, it sounds like it is not specific to a drive mode, it simply reacts to throttle response combined with gear setting. Of course the manual mode blocks cylinder deactivation. With that said, I think Chevrolet dropped the ball BADLY. I would think the cylinder deactivation would only work in the ECO mode. If you are going for a long interstate drive and switch it to ECO, then it would make since to run on 4 cylinders at cruising speed. But in Touring or Sport mode? Not so much. I know people are using the Range module to bypass this process, but they seem to have their own set of problems. This is probably the biggest obstacle to me buying a new Grand Sport.

Kracka

Why would you allow something so simple to deter you from buying an amazing car? If AFM ends up irritating you, just disable it. Or, buy a M7 and that way the car only uses V4 while in Eco mode just like you want.

bsterling9

Simple? Have you seen the number of problems with the A8 transmission reported on this forum in regards to the AFM? Sorry, I don't think having a TC or transmission go bad on a 70K car is "simple".

Kracka

Buy the M7 then, it's a great transmission; I had zero issues with it, or running in Eco mode on numerous cross-country roadtrips. If you want the A8 though and are worried about AFM, just disable it...or let the warranty do its job and not worry about a thing.

smbsocal

Just get the Range AFM deactivator and you won't have any issues.

bsterling9

Yeah, I probably used the wrong term about buying a new GS. It's not an obstacle, just a concern. However, the percentage of people having problems is far fewer than those not having problems at all, so I am probably just being a little crazy. I would love an M7, but I want to make it enjoyable for my wife to drive, so we will probably just go with the A8. I will step off my soap box now.

KennyG MacMulkin

I'm sorry nobody could help you. Next time you have a tech related Corvette Question, etc. Please don't hesitate to reach out to me. I may be in competition with other dealers for sales, but I am here to help each and every Forum Member and Corvette Owner that has a question. Enjoy your Day and Save the Wave!!

KennyG MacMulkin

From my experience with a few thousand C7's being serviced and sold. The A8 problem is being way overblown. In my opinion, the failure rate on them is no more than any other retail product being sold today. but if you come on the forum, you may never want to buy a Vette with some of the things you see and hear.

bsterling9

Thank you so much Kenny! I will certainly let you know if I have any questions and I will let you know when I am ready to buy as well.

mountainears

It's in the manual, but somewhat written a little vague, they could drill the message in a little further.

Page 204 of the 2017 manual says "With manual transmission: Active Fuel Management only active in Eco mode". So I read that as if you have an A8, it is active in EVERY mode. Never does it explicitly state that it is available in only one mode, that section starts off describing what it does and says it is a normal function and it "changes to 4-cylinder mode when coasting"

davepl

That's why you buy a Z, since they don't have [widespread or common] A8 issues... those are Stingray issues.

2K14C7

This is from the 2014 Owners Manual:

Normal with automatic transmission: The engine uses 8-cylinder mode when accelerating, but changes to 4-cylinder mode when coasting.
With manual transmission: Active Fuel Management only active in Eco Mode.
Active Fuel Management (engine cylinder shuts off)
4-Cylinder Mode
Off in Manual mode with automatic transmission unless in Eco mode.
Eco keeps the engine in 4-cylinder mode unless heavy acceleration is needed.