AFM question
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
AFM question
I just bought a very nice 17 ZO6 with 30k miles.
I drove it back from Fl to TX and was unable to engage 4 cyl operation at any time except E mode when coasting or with VERY light throttle.
I realize that I didn't buy the Z for gas mileage but I wonder if what I experienced indicates something else.
Your thoughts. pls
I drove it back from Fl to TX and was unable to engage 4 cyl operation at any time except E mode when coasting or with VERY light throttle.
I realize that I didn't buy the Z for gas mileage but I wonder if what I experienced indicates something else.
Your thoughts. pls
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From: Northern Illinois
2023 Corvette of the Year Winner - Modified
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I tried E mode a little when I drove my Z06 home from Alabama 2800 mile trip had to play with some of the modes. I noticed the computer at 90 mph was saying i was getting 32 mpg.. lol That was last time I ever used E mode The way I usually drive probably more like 8mpg 
Tech Contributor
Joined: Oct 1999
Posts: 41,058
Likes: 9,817
From: Charlotte, NC (formerly Endicott, NY)
I just bought a very nice 17 ZO6 with 30k miles.
I drove it back from Fl to TX and was unable to engage 4 cyl operation at any time except E mode when coasting or with VERY light throttle.
I realize that I didn't buy the Z for gas mileage but I wonder if what I experienced indicates something else.
Your thoughts. pls
I drove it back from Fl to TX and was unable to engage 4 cyl operation at any time except E mode when coasting or with VERY light throttle.
I realize that I didn't buy the Z for gas mileage but I wonder if what I experienced indicates something else.
Your thoughts. pls
Bill
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
AFM Question
thanks Bill
i understand your response which makes sense.
However, the 2015 Stingray A8 that I am selling will shift to 4 cyl at 75 in 8th gear easily and stay there in E,T or S
So, I’m wondering if I have a torque converter problem (which my 15 had before GM) replaced it) or improper programming or ?
your thoughts?
will
i understand your response which makes sense.
However, the 2015 Stingray A8 that I am selling will shift to 4 cyl at 75 in 8th gear easily and stay there in E,T or S
So, I’m wondering if I have a torque converter problem (which my 15 had before GM) replaced it) or improper programming or ?
your thoughts?
will
Tech Contributor
Joined: Jan 2015
Posts: 5,692
Likes: 1,451
thanks Bill
i understand your response which makes sense.
However, the 2015 Stingray A8 that I am selling will shift to 4 cyl at 75 in 8th gear easily and stay there in E,T or S
So, I’m wondering if I have a torque converter problem (which my 15 had before GM) replaced it) or improper programming or ?
your thoughts?
will
i understand your response which makes sense.
However, the 2015 Stingray A8 that I am selling will shift to 4 cyl at 75 in 8th gear easily and stay there in E,T or S
So, I’m wondering if I have a torque converter problem (which my 15 had before GM) replaced it) or improper programming or ?
your thoughts?
will
it’s normal.
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Moderator
Joined: May 2010
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From: Northern Illinois
2023 Corvette of the Year Winner - Modified
2022 C7 of the Year Winner - Modified
St. Jude Donor '18 thru '25
I think most agree that sounds normal, many use range disablers and such to get around it.. I would not be concerned. I can speak for the Z owners I know, we just don't care or drive much in the fashion that would allow 4 cylinder mode nor use economy mode...
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
AFM question
My OE powertrain warranty is about to expire so I dropped it off at my Chevy dealer this morning.
the service writer agrees that something is not right.
I will post again when I get the diagnosis
the service writer agrees that something is not right.
I will post again when I get the diagnosis
Tech Contributor
Joined: Oct 1999
Posts: 41,058
Likes: 9,817
From: Charlotte, NC (formerly Endicott, NY)
thanks Bill
i understand your response which makes sense.
However, the 2015 Stingray A8 that I am selling will shift to 4 cyl at 75 in 8th gear easily and stay there in E,T or S
So, I’m wondering if I have a torque converter problem (which my 15 had before GM) replaced it) or improper programming or ?
your thoughts?
will
i understand your response which makes sense.
However, the 2015 Stingray A8 that I am selling will shift to 4 cyl at 75 in 8th gear easily and stay there in E,T or S
So, I’m wondering if I have a torque converter problem (which my 15 had before GM) replaced it) or improper programming or ?
your thoughts?
will
Bill
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
AFM question
Bill
by “sufficient when the engine is running on 4 cylinders “ do you mean that the torque is sufficient to kick the 4 cylinder operation off and revert to 8 cylinder operation?
Thanks
will
by “sufficient when the engine is running on 4 cylinders “ do you mean that the torque is sufficient to kick the 4 cylinder operation off and revert to 8 cylinder operation?
Thanks
will
Tech Contributor
Joined: Oct 1999
Posts: 41,058
Likes: 9,817
From: Charlotte, NC (formerly Endicott, NY)
Bill
Drifting
Joined: Jun 2002
Posts: 1,303
Likes: 151
From: Las Vegas Nevada
My 2017 Z06 Z07 package - seldom goes into v4 mode, especially since I installed both front and rear stage 3 aero (wicker full up and front wings). Before the stage 3 aero, it would go into v4 mode occasionally.
If I am on a downhill section of the freeway at about 65 mph and in eco or tour mode, it will sometimes go into v4 mode - I have to watch the dash to see that it changed - almost no noticable feel that the car has gone into v4 mode (very smooth transition).
Jim
If I am on a downhill section of the freeway at about 65 mph and in eco or tour mode, it will sometimes go into v4 mode - I have to watch the dash to see that it changed - almost no noticable feel that the car has gone into v4 mode (very smooth transition).
Jim
Race Director
Joined: Apr 2014
Posts: 10,430
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From: North Texas
Pretty much the same for me. I also have an A8 with stage 3 aero. It hardly ever went into v4 mode on the highway unless on a steep downhill. I went ahead and put a Range Device on it anyway.
Safety Car
Joined: Mar 2004
Posts: 4,048
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From: South Florida
Yup I have a 2017 M7 and even in Eco mode, v4 never activates if I'm going over 70mph. The only way to really make it work is to go 65mph in the right lane nice and slow. Then it will pop into V4 mode and you can "hyper mile" lol. While I never do this, I did test it out and was getting 26-28 mpg which is pretty amazing. If I ever need to get somewhere slow and lean, that is an option.
However, the car is no longer stock and I removed v4 mode in the tune long ago. I never use it and still get around 20mpg on the highway in v8 mode on E60 going 70ish MPH.
However, the car is no longer stock and I removed v4 mode in the tune long ago. I never use it and still get around 20mpg on the highway in v8 mode on E60 going 70ish MPH.
Melting Slicks
Joined: Aug 2014
Posts: 2,587
Likes: 873
The aero pieces for stage 2/3 really kill the v4 mode on my m7. With stage 1 ish, I could get the v4 mode to activate in 6th gear (sometimes 7th) depending on how flat the road was and the load level versus speed. The stage 2 aero adds just enough drag that 7th is all but impossible unless I am going down hill and 6th doesn't do that much better in mileage vs 7th even when it does kick in.
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
AFM question
the GM tech rep was in town today and he reprogramed the AFM to factory specs and now the AFM works as it should. The mpg shown when in V4 mode is lower than that on my 15 Stingray but that’s to be expected w the Supercharger.
now the mpg jumps from 19 to 24 when switching from V8 to V4
the tech rep stated that the AFM learns from how the car is driven. From the maint and repair record on th GM server, the first owner drove in a very spirited manner. So, apparently the AFM learned that it was not to be called upon so it reprogrammed itself down
a five mpg is not a big deal even at $6 a gallon but now I’m comfortable that there is nothing seriously wrong with the transmission
your comments?
now the mpg jumps from 19 to 24 when switching from V8 to V4
the tech rep stated that the AFM learns from how the car is driven. From the maint and repair record on th GM server, the first owner drove in a very spirited manner. So, apparently the AFM learned that it was not to be called upon so it reprogrammed itself down
a five mpg is not a big deal even at $6 a gallon but now I’m comfortable that there is nothing seriously wrong with the transmission
your comments?