Have 2017 Z A8, 840 miles, put in eco drive mode then set control for 75 MPH, driving mode selector shows "ECO" BUT no cylinder display showing "V4" operation in center cluster

Just returned from vacation were I rented 2016 Stingray, when in cruise and ECO mode, small green "V4" appeared in center display

is there a problem???? with instrument cluster????


Thanks guys!

 

Mine is 2015. V8 or V4 only shows in the instant fuel economy mode.
Do not recall if I was in "eco" mode or not??? And not my picture, but represents where I see it.

 

There is a display in lower right of the other display, very discreet, you have to look for it closely.

 

Yep only works in Eco on that screen on a coast. Funny thing I tried Eco on my trip. I got better gas mileage in Touring than I did in Eco.. My car will never see Eco again. Waste of time and V4 was brief if at all on...

Edit My car is a M7, The A8 should show it in any mode on instant fuel screen.

 

Manual Transmission only go into V4 in ECO mode, A8 goes in V4 in all modes unless using Manual shift position.
This is my picture in tour mode showing V8 at the time of being parked. Will go into V4 if at a cruise.

 

My 2017 Z06 does the same thing. Only goes into 4V when I'm coasting, and not always then. Never seen to do it in Eco mode, although I don't use that often.

 

I use Eco all the time when driving long highway distances -- I have a 2015 M7. The mode switches to V4 more often in 6th gear than in 7th. Seems the V8/V4 transition is sensitive to load.

 

I just used Eco mode in my '17 M7 with 2,800 miles for the first time this past weekend. Was in 7th gear, and @ 65mph, would slip out of V4 and back to V8 when experiencing a small load increase. Didn't think to try it in 6th gear. Showed 33 instant mpg in V4, and 29 in V8 mode.

 

Don't know if this is true about the system, but on my 2,600 mile road trip I May I was never able to get it to show V4 mode if my speed was over 70 mph. Under 70 it showed up, but over 70 (all the time on cruise control) I never saw it. Can it be that it simply doesn't function over 70 or some other specified speed? And yes is does seem very sensitive to load and mostly worked going on a slight downhill. The owner's manual is strangely silent on this. --Bob

 

Here are the general parameters that must be met (this is from an A8). For example coolant temp must have reached at least 97F, you can't be over 3200rpm, 40% throttle, and so on. I don't see (and did not expect to see) any max speed.

 

Dave,
thanks for posting the parameter data for V4 operation.

I either have my Range anti-AFM module turned on or I have the A8 in manual mode to avoid V4 operation given its negative impact upon the A8 torque converter lockup clutch.

It will be interesting how the engines that have run often in V4 mode react with higher miles; uneven cylinder wear was a concern expressed by one of the major Japanese manufacturers when deciding against AFM type engine strategies. A compression test of a high operating hour engine would provide a good indication whether this is a valid concern.

Some of the previous generation truck engines using AFM (same system but then referred to as DoD or Displacement on Demand) experienced significant oil usage as the miles added up and that issue was one of the problems solved with the Range module. Once piston ring sealing becomes less than perfect I can see that this would easily become a significant problem as AFM (aka DoD) is designed to collapse the lifters at the point when the cylinder has an air charge and that air charge is retained being compressed on the upstroke and then returning to static pressure on the downstroke but since the intake and exhaust valves remain shut the entire time that cylinder is shut off then any of the air mixture leaking by on the compression portion of piston movement will result in increasing levels of vacuum on the reverse motion possibly reaching the point where it replenishes the charge by pulling crankcase vapor (and cylinder wall oil) past the rings.

Even if I didn't have the A8 which runs into V4 mode problems in the short term I wouldn't want V4 mode frequently active on any engine I planned to run into high mileage given previous issues with the system.
It is probably marginally better on direct injected engines since there isn't unburnt fuel in the "dead" cylinder mixture with the current generation of smallblock engines.

 

To alleviate all these parameters, just keep your foot in it.

 

Try dropping down a gear into 6th on the highway. I noticed at 70 mph in 6th the engine stayed in V4 mode longer than when running over the same stretch of highway in 7th. In 7th every little slight upgrade in the pavement resulted in the car switching to V8 mode whereas in 6th it stayed in V4 mode.

Bill

 

My 2016 A8 Z06 rarely goes into V4. It is slightly more common when in ECO mode but even then rare. More often it occurs during a deceleration or downhill.

My lifetime MPG average is 17.3 so I am happy. With the way I drive that is amazing.

 

My average over the past 26,000 miles has been 19.9. I drove moderately hard. Frank

 

So as far as I can tell from Dave's published parameters, vehicle speed is not one of the parameters to determine whether to use V4 mode, so my theory is wrong. Still, I was surprised that I never seemed to be able to get V4 activated over 70. I assumed it simply required too much power to beat the aerodynamic drag at the higher speeds. --Bob

 

When I had my 14' A6 I was able to V4 at high 90MPH many times. I know I got it one time for sure ( not coasting) at over 100 MPH

 

I'll try 6th, but to be honest I have a lead foot and would rather enjoy my drive over hit 4V mode... LOL

 

I just bought a barely used Diablosport i2 Tuner from a fellow member and I don't even know if I'll use the tuning portion of it...I just wanted the ability to bypass the stupid cylinder deactivation on my 650hp car!

 

Mine also doesn't seem to ever want to go into ECO Mode when above 65MPH cruising on a 15Z A8.