Certain C8 Features - Can they be defeated?

[VJPVJP]

My understanding is that the C8 will include 1) Cylinder de-activation and 2) Start-stop......Can these "features" be defeated (i.e. Turned off) easily, as with a button? I mean, who buys a 495 HP car to run on 4 cylinders, or cares about a few cents worth of gas by shutting the engine down at every stop???

[meyerweb]

No Start Stop. GM has confirmed that.

We're not sure about cylinder deactivation. One GM person said that if you put the car in track mode it disables AFM, but we don't have confirmation of that. On the C7, if you put the transmission in manual mode, it disables AFM. That may be true on the C8, but again, we just don't know yet.

We'll probably get that information next month, when the magazines release their full road tests, and GM is rumored to be releasing all the performance specs.

[TOMDOM69]

there is no start stop, and if you aren't driving conservitavely it won't go into 4 cylinder mode.

[VJPVJP]

Folks, thank you for your responses.............Is cruising on the highway at legal speeds considered "driving conservatively"......I don't EVER want to see that my C8 is running on 4 cylinders and just dragging the other 4 along........

[73shark]

I don't know if they ever perfected it but I do know that the first Tahoes that had it, ate up a lot of engines that had the AFM. I do know that the two Tahoes that I owned with it hardly ever enabled it either in City driving or on the road.

[LSECO]

I have a manual transmission car that encouraged me to skipshift when not in trackmode.I pulled the plug on that on day 3 of ownership.

[Milliwatt Rob]

No start stop, but it will have AFM. In what modes AFM will be active is not yet known. In the C7, the AFM could be totally defeated with the use of an OBD2 plug in device from Range Technologies. Perhaps such a device will also work in the C8.

[ZORA 1]

i think the DOD , is supposed to be able to cycle from 1 to 8 cylinders , and rotate them to keep temps in a narrower range

[Swift93]

I recall someone, perhaps John, mentioned that the only time it would drop cylinders is in auto. I could be mistaken.

[Unclestu]

On my C7's The AFM was disabled in Sport and Track modes. I suspect that will be the same with the C8.

[Michael]

i think the DOD , is supposed to be able to cycle from 1 to 8 cylinders , and rotate them to keep temps in a narrower range

The C8 engine has "Active Fuel Management" which disables four cylinders. Some other GM engines have "Dynamic Fuel Management" will can vary the number of cylinders deactivated.

[capevettes]

From what I have read and heard, the only way the C8 won't go into cylinder deactivation on the highway is if you are in paddle shift mode.
My C7 Z06 was a manual, so it would only rear it's ugly head in Eco mode, which I avoided.

[73shark]

FWIW, the Tahoe AFM shut down the same 4 cylinders (2, 3, 5, & 8) and could run a maximum of 10 minutes continuous at which time it would have to shut off to equalize cooling.

[Imaposer]

My C7 is a manual, and never gets put in eco mode, so it is a non issue. I am really hoping this is one of the little things they are addressing with the Z mode button. Letting you set up everything to a preferred setup that you can get at the push of a button. Exhaust to track mode, AFM to track mode, suspension to tour, etc. I don't want to run around all the time in track, or even sport mode all the time, so hope I can get the settings in Z mode to take care of this.

[John]

Exactly what capevettes noted, that if you stay 100% in manual mode (never in Dirve/“D” where the DCT chooses what gear you are in), you will not once have any cyclinder deactivation.

If you choose to be in Drive, and are using lots of throttle, such going up hills calling for a significant engine response, then even in D you will not be in cylinder deact. But on level roads, going down hills, minimum throttle pressure situations and similar, your C8 will go in an out of 4 cylinder to 8 cylinder modes (only two options on the C8), and back and forth again — as determined by your car’s combined DCT/ECU systems.

Last what meyerweb stated, that it has been reported but not officially verified, that in Track mode, it does not use cylinder deact.