mulalleybs

I just had a quick question. I've owned my A8 '15 Z for about a week now and have put almost 400 miles on it. When I drive to and from work about 20 miles each direction, I usually put the car in eco mode.

I've watched the instant fuel economy gauge where it displays what mode the car is in as well quite a bit. I cruise control 30, 54, and 64 regularly and have never once seen the car go into v4 mode. The car is 100% stock, so I'm at a loss as to why it's never de-activated.

Any ideas?

Brett

silver74vette

I do not think this is used during the break in period. You may see it change once you exceed 500 miles. Getting the rings to seat with the cylinder deactivated would be difficult.

Just my guess....

mulalleybs

There's about 6k miles on the car now

Sweptclean

Cylinder deactivation will happen if you are on a completely level road, or going down hill. In other words, no throttle input to maintain speed.

mdz06vetter

Not positive, but thought ECO kicked in during highway driving at a constant speed - not for city driving which you seem to do at varying speeds........

ajrothm

My car only goes into V4 when going down a hill or when coasting on a flat road with no throttle input. Basically AFM is useless on the Z06.

On my wife's '16 Camaro SS, it goes into V4 all the time, even on the gas slightly, say 10% throttle or less, it will stay in V4. There is a huge difference between the two in AFM function.

mulalleybs

I'll try again tomorrow in some downhill areas while leaving it in current fuel mileage the entire time to see if it ever switches from V4 to V8. I'll report back my findings. I appreciate the help as always gentlemen.

Also... just found out about launch control. I'll have to test that out too.

FWIW I did read the owners manual but started to doze off, so I didn't absorb all the info. Did learn a few things, though. For some reason, reading things like manuals and college textbooks make my eyes incredibly heavy and I doze right off.

djnice

If you put the trans in M it won't go into V4. You don't have to be in eco to get V4 to occur with the A8. If it doesn't go into V4 it might have had a tune done that disabled AFM.
Your lucky, my 17 GS goes into v4 all the time and it did it when breaking-in. There is lots of false info floating around on what the computer does during break-in. For example, it will rev past the break-in 4500 rpm.

mulalleybs

Alright, I can safely say it's not going into de activation. I'll message the previous owner and see if he did anything to affect that.

mulalleybs

not sure about being lucky. I'd like to maintain my factory warranty.

BOBSZ06

Does not have to be in "Eco" mode to V8>V4.
Tour mode will work as well....while in Auto Drive.

mulalleybs

yeah, I just had it in eco because it's supposed to be more aggressive I think.

Anyway, looks like I need to have dealer reflash the computer

CPhelps

It might also be worth checking your ODBII port to see if it has one of the "AFM commander" plug in modules that disables AFM that way.

pfg1

I have driven my 2015 M7 on a number of long 2500 mile trips, sitting there while watching the display at 75 mph with cruise on. Even on a flat road with no headwind, it hardly ever goes into V4. Seems strange that with all that low end power it would not pull out the cylinders.

ronsc1985

I have a 2017 m7 and the only time I see it go into v4 mode is going down hills or coasting on level ground.

It seems to be a minor effect anyway as the instantaneous mpg doesn't change all that much.

That said I don't really GAF since if I was worried about mileage I would have bought a Honda Civic.

Florida2000

paddle shift in manual mode (M) and forget about AFM, except of course for max 0-60 or 1/4 miles times, with or without launch control, in which case fully auto (D) is impressive.

rbartick

My 2016 M7 will only allow V4 mode in Eco. I see V4 mode quite often when cruising with light throttle in the lower gears. The car is much less likely to enter V4 mode in top gear on the highway, even with the cruise control on. Any slight incline will turn it off.

mulalleybs

Dealer reflashed. Good to go!

djnice

That's cool they didn't hassle you about warranty or anything because it could have possibly been tuned previously.
So good to go means you tested it and V4 activates now? Is it working good?

mulalleybs

Yeah. It deactivates now. There isn't any change in power delivery as far as I can tell, so I believe only the afm was disabled. With 4 years remaining on the warranty, I want to make the most of it!