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So I picked up my new car and drove 100 highway miles home, which gave me the chance to try ECO mode. What I observed was that as long as I kept the car under 72 MPH, whenever the highway was level (or downhill) the car would go to V4 mode, or at least the V4 indicator would display on this screen. Very cool for long highway trips.
BUT BUT BUT . . . then I left this screen on, and tried *other* modes. And, surprisingly (to me), the V4 indicator would display whenever speed leveled out, in *any* mode. As you can see from the photo, here I am in Tour mode, and the V4 indicator is on, and I also tried it in Sport mode, same thing.
Now I'm not opposed to saving fuel, but I am opposed to half my cylinders going on vacation whenever they want. Can someone tell me what's going on here?
My understanding is that your car is functioning exactly as designed for automatics. I think only the manual transmissions can lock out 4 cylinder mode. You might be interested in an AFM Disabler from Range. Search the forum and you can see that most people love them. I bought one but haven't tried it out yet.
your car is an A8 auto, GM uses the V4 cyl deactivation for gas mileage.
you can put your car in manual to prevent this.
I selected manual for much of my first miles in the car. Pushing dead cyl.
did not make much sense for engine break-in.
Also search on trans/TC shudder-you may find this interesting.
Picked one up for sale on the forum not too long ago and after having the car for 2 years I am beating myself up for not having it sooner. Some of the issues that came with AFM are now gone such as the periodic rumble strips sensation.
People are often selling them on here because they end up disabling the AFM through a tune or just selling the car. I will be doing the same once the warranty expires.
Thank you for the info. I just tried it, and you're absolutely right. The only real downside is the constant upshifting required with an 8sp trans.
On the highway in cruise at 70 mph why would upshifting or downshifting be required? I have an M7 and rarely shift the car unless there are traffic lights, stop signs, right angle turns in town or traffic impeding my travel. Just put the car in a single gear and leave it there. In traffic take it out of manual since V4 mode won't engage when creeping along at low speeds.
Around town I drive in 5th or 6th gears depending on the speed being driven. On a 50 mph city street that means I am in 6th gear with rpms somewhere around 1500. That leaves plenty of throttle response for acceleration without even thinking about downshifting. We aren't driving some rubber band driven econo cars with no torque that require a lot of shifting. I can start my car from a dead stop in 4th gear and never have to shift until I hit the rev limiter at about 152 mph.
Another vote for the Range AFM Disabler. Got mine a few weeks ago and have not seen V4 since. Car functions perfectly. Get it directly from Range to be sure your unit is new and has the latest firmware. $189 with coupon code "FEELTHEPOWER" on checkout.
V4 function in *all* modes
