22c8z51

What AFM defeat device is everyone using? I don't like the irregularity of sound as it goes up and back between 8 and 4.

16falcon

As far as I know, there is not one for the C8. Some people are driving in manual shift mode, that disables V4 mode. Track mode does too, but I think that is impractical for street driving.

It doesn’t bother me, I don’t even hear it.

Red Mist Rulz

16falcon is correct. The Range disabler doesn't work on the C8, and there aren't any other devices available. Driving in Z mode with the engine/transmission set to track will disable AFM while letting you set the other items to something other than track. Or manual mode.

MarkMeHopeful

You can only defeat AFM by shifting in Manual Mode, putting the car in Track mode, or using Z-mode with engine/transmission set to track (as described above.

Foosh

I barely notice the transition at all. I did notice a "judder" on the C7, but the system in the C8 is much refined. I like the system. On a long interstate road trip, why not save some fuel?

Vetteman Jack

Seems like the C8 works better in the AFM transition than the C7, at least that is what is being reported.

Thunder22

I've only had my 2023 HTC for a week, but I can hear it when AFM kicks in.

undecided1965

My only concern with AFM is the difference in wear between the 2 sets of cylinders (AFM vs Non-AFM).

RKCRLR

The difference is negligible. The AFM traps combustion products in the AFM cylinders to act as springs. So the pressure in the AFM and non-AFM cylinders is similar. And AFM is only used at low throttle positions. It doesn't take much throttle to kick the engine out of AFM operation.

Foosh

^ Very true. A barely negligible throttle increase reverts back to V8 mode.

On the sound, I wonder if there are variations in cars. I've been listening for it, and haven't heard a peep.

johnodrake

On my recent 2200+ mile trip I got as much as 31+mpg and the AFM system was not noticeable at all.

Fast Dawg

I never noticed it in my C7 either. I am guilty of playing a lot of classic rock very loud on stereo systems I custom built for my cars back in the day. That might explain it.

Red Mist Rulz

It was very noticeable on a C7 with a manual trans, but not so much with the automatic. On the C8, if it weren't for the indicator on the dash and the change in exhaust note which I can sometimes hear, I'd never know what mode it was in.

Foosh

I often mute the stereo, but have MyMode set at max loud on the exhaust, and I've never heard anything. I also use the paddles most of the time even in auto mode. However, I have tested a dozen or so times listening for it with exhaust quiet in Tour, and nada.

22c8z51

Yeah AFM is great for highway MPG. 99% of my driving is not highway, and it cycles on and off quite a LOT. Yes I hear it switch, and yes the exhaust sound is different. While I appreciate the innovative feature, it detracts from my own experience. Track mode engine/trans is fine for defeating it, but it's far too eager to downshift with the slightest increase in throttle. And I don't want to paddle shift it all the time just to drive a v8 full time and not have hair trigger downshifts.

I hope Range comes up with something. I know this is a first-world problem, but c'mon.

Red Mist Rulz

Unfortunately, I suspect the heavily encrypted electronic architecture in the C8 will lock out devices like the range.

Shoal07

In a 1000mi road trip last week all I noticed was I could hear (what I presume) are the AFM valves when it switched to V4 mode. To me, it sounded like a sucking of air like I hear on my truck intake when I juice it. I only made the connection because I had a lot of time to figure it out. I don't notice any difference between V4 and V8, other than the whoosh sound when it goes into V4 mode. There is no lag coming out of V4 mode either.

zet06

Drive it in tour and reap the mileage. I do not even notice the comings and goings of the 4 cyl mode. . My C7 had a shudder. especially when you hit a hill and it leaped into V8 mode. The C8 is great.

op z

There is some mention in this thread about Z mode in the track setting. Isn't Z mode its own mode and not dependent on the mode setting prior to hitting the Z mode button?

Undy

Z Mode is a programmable button on the left side of your steering wheel that allows you to custom mix a variety modes. You can program braking, suspension, exhaust, etc, to your liking. Simply press the button and you're there. To me, my definition of a "mode" is anything available by turning the rotary dial on the console. If you take that out of the equation then i guess you could consider it a mode.
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