Consensus on C7 Corvette and cylinder deactivation?
09-21-2014, 11:51 AM
#21
Burning Brakes
First, agree with others that do not think OP is a troll.
As to the issue, I am generally fine with it and believe it adds a mpg or two on the road. I do wish, as an A6 owner, that it operated more like the AFM in the M7 configuration (only in Eco). Or at a minimum, didn't operate at all in Sport or Track Mode.
As to the issue, I am generally fine with it and believe it adds a mpg or two on the road. I do wish, as an A6 owner, that it operated more like the AFM in the M7 configuration (only in Eco). Or at a minimum, didn't operate at all in Sport or Track Mode.
09-21-2014, 11:57 AM
#22
Le Mans Master
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AFM - This is one of the reasons I've found to buy the 7 speed manual (like I need a reason other than I like a manual).
With the 7 speed, the AFM has to be activated using the eco mode. Otherwise, it stays off.
With the 7 speed, the AFM has to be activated using the eco mode. Otherwise, it stays off.
09-21-2014, 01:25 PM
#24
AFM has nothing to do with keeping the C7 from a gas guzzler tax. It does have everything to do with meeting the CAFE numbers. Gas guzzler tax and penalties paid for not meeting the CAFE are two different things.
My C6 Z06 does not have the AFM and did not have a gas guzzler tax imposed on it. It has a EPA rating of 15/24, far below the fuel mileage that a C7 would get without AFM. The base C6 is rated at 16/26 and the base C7 is rated at 17/29. A large part of that 29 mpg on the highway was accomplished with the additional 7th gear overdrive on the C7, the DI and the VVT.
Cliff note: elimination of the AFM on the C7 would not cause the C7 to drop into gas guzzler territory(less than 22.5 MPG).
My C6 Z06 does not have the AFM and did not have a gas guzzler tax imposed on it. It has a EPA rating of 15/24, far below the fuel mileage that a C7 would get without AFM. The base C6 is rated at 16/26 and the base C7 is rated at 17/29. A large part of that 29 mpg on the highway was accomplished with the additional 7th gear overdrive on the C7, the DI and the VVT.
Cliff note: elimination of the AFM on the C7 would not cause the C7 to drop into gas guzzler territory(less than 22.5 MPG).
09-21-2014, 01:39 PM
#25
Team Owner
09-21-2014, 02:07 PM
#28
Jukebox Graduate
09-21-2014, 02:12 PM
#29
Intermediate
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First, agree with others that do not think OP is a troll.
As to the issue, I am generally fine with it and believe it adds a mpg or two on the road. I do wish, as an A6 owner, that it operated more like the AFM in the M7 configuration (only in Eco). Or at a minimum, didn't operate at all in Sport or Track Mode.
As to the issue, I am generally fine with it and believe it adds a mpg or two on the road. I do wish, as an A6 owner, that it operated more like the AFM in the M7 configuration (only in Eco). Or at a minimum, didn't operate at all in Sport or Track Mode.
05-27-2017, 10:48 PM
#30
Cylinder Dectivation
I have a manual transmission in my 2014 Corvette and I find the cylinder deactivation to be annoying. Plus, I performed two back to back 50 mile tests on a long trip with the cruise control activated to compare gas milage in 7th gear with deactivation vs 7th gear w/o deactivation. The deactivation mode was only 1/10 of a mpg better, so why put the drive train through the labor of deactivation.
05-27-2017, 11:25 PM
#31
If you find it to be annoying, do not use Economy mode. One of the great advantages of the M7 over the A6 or A8 is that you will never see cylinder deactivation unless you are in Economy mode.
When tested using the EPA fuel economy protocol, the car does much better than a 1/10 mpg improvement, thus obviously your driving style is quite different than the EPA test procedure. That's not unusual, most people's are.
Nonetheless, GM needs to meet a certain CAFE rating per the EPA test, and they wouldn't be doing it if it weren't necessary to achieve that rating. The same applies to CAGS (1-4) shift, which is also there for the EPA protocol and CAFE reasons.
When tested using the EPA fuel economy protocol, the car does much better than a 1/10 mpg improvement, thus obviously your driving style is quite different than the EPA test procedure. That's not unusual, most people's are.
Nonetheless, GM needs to meet a certain CAFE rating per the EPA test, and they wouldn't be doing it if it weren't necessary to achieve that rating. The same applies to CAGS (1-4) shift, which is also there for the EPA protocol and CAFE reasons.
Last edited by Foosh; 05-27-2017 at 11:27 PM.
05-27-2017, 11:48 PM
#32
E-Ray, 3LZ, ZER, LIFT
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From reading many posts on the subject in that time period, it appears the torque converter makes it more seamless. Makes sense.
Don't spend that much time on the Interstate, which is the only time I am in 7th gear and usually on cruise control. Not worth fiddling around with the Mode selector to get it to go into 4 cylinder mode for a few mpg gain in my short run.
05-29-2017, 09:57 PM
#33
If you find it to be annoying, do not use Economy mode. One of the great advantages of the M7 over the A6 or A8 is that you will never see cylinder deactivation unless you are in Economy mode.
When tested using the EPA fuel economy protocol, the car does much better than a 1/10 mpg improvement, thus obviously your driving style is quite different than the EPA test procedure. That's not unusual, most people's are.
Nonetheless, GM needs to meet a certain CAFE rating per the EPA test, and they wouldn't be doing it if it weren't necessary to achieve that rating. The same applies to CAGS (1-4) shift, which is also there for the EPA protocol and CAFE reasons.
When tested using the EPA fuel economy protocol, the car does much better than a 1/10 mpg improvement, thus obviously your driving style is quite different than the EPA test procedure. That's not unusual, most people's are.
Nonetheless, GM needs to meet a certain CAFE rating per the EPA test, and they wouldn't be doing it if it weren't necessary to achieve that rating. The same applies to CAGS (1-4) shift, which is also there for the EPA protocol and CAFE reasons.
05-30-2017, 07:45 AM
#34
Drifting
Its a Corvette don't use or need 4 cyl mode.
05-30-2017, 07:58 AM
#35
Race Director
3 year old thread, back from the dead
05-30-2017, 08:21 AM
#36
Yes, but new people show up here all the time wanting to engage in discussions of things they are curious about. Give them credit for searching and finding the old threads instead of starting new ones.
05-30-2017, 08:24 AM
#37
Le Mans Master
I am averaging like 16mpg. So I doubt there is any cylinder deactivation going on in my car 
05-30-2017, 08:29 AM
#38
Pro
Mine had a noticeable clunk when it changes modes so I quit using it. Maybe I should try again. We averaged 27 mpg for the 720 mile Talladega trip including 10 laps around the track, in town, and 75-80 mph on the interstate.
05-30-2017, 09:12 AM
#39
Melting Slicks
I use it all the time driving long distance in my m7. I think it's good for about 2 mpg. If you're cruising down the interstate 70+ why not use it? Seen my brother's L76 haven AFM lifter issues even with afm tuned out right away, so I don't think it prolongs the life of the engine to avoid it. If I had an A8 I'd perma disable it to prolong TC life though.
