So if you don’t use Eco mode the engine won’t go into V4? Sport, Tour and Track won’t allow it….even on a long straight easy cruise?

 

As long it is a manual it will not go into v4 mode unless you use eco mode. An auto will go into v4 mode unless you put the transmission in manual shift mode or plug a range device into your car.

 

As long it is a manual it will not go into v4 mode unless you use eco mode. An auto will go into v4 mode unless you put the transmission in manual shift mode or plug a range device into your car.


ok…I got it now……thanks!

 

I can’t for the life of me understand why they didn’t follow the same protocol for the A8 so users could also choose whether or not they want to use V4 mode or not by simply selecting or not eco mode. Instead those of us with the auto box have to buy the range device to prevent it.

 

In Europe you have to activate the ecco mode A8 or 7M.

Default is off in both transmissions.

 

That is simple to answer. The engine load changes and there is insufficient power available to drive the car without switching back to V8 mode. American roads are far from smooth so what looks like a level highway has lots of small dips you don't even notice but the drivetrain notices them. When the car enters a small dip AFM switches to 4 cylinder mode and as soon as it starts to crawl out of the dip it switches back to V8 mode. This is very noticeable in 7th gear in the 70-75 mph range where 4-cylinder mode barely has sufficient torque to maintain speed. The engine spends most of its time in V8 mode. However, shift to 6th gear and drive the same speed and the engine stays in 4-cylinder mode much longer. Drive in 4th gear and it stays in 4-cylinder mode almost all of the time unless it actually encounters a noticeable hill. I found I get better gas mileage on the road if I use 6th gear at speeds up to 75 mph and 7th gear after 75. In 6th gear the engine runs in 4 cylinder mode more of the time. So even though it is turning a few hundred more rpm at 70 mph it is using close to half the fuel when running in 4 cylinder mode.

I suspect what damages the lifters is constantly shifting from 8 to 4 and back to 8 Vs letting them run longer in 4 cylinder mode. The constant shifting with the A8s is what seems to drive the TCC and torque converter failures. The range device stops the shifting.

Bill