Afm
Administrator
Joined: Mar 2001
Posts: 368,324
Likes: 24,777
From: In a parallel universe. Currently own 2014 Stingray Coupe.
C7 of the Year - Modified Finalist 2021
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St. Jude Donor '03 thru '26
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Drifting
Joined: Jul 2016
Posts: 1,910
Likes: 1,167
From: Keswick, Virginia
Yep; if you have a C7 with the A8, that AFM will kick in all the time unless you drive in manual mode. If you have the M7, then the car will only go into V4 operation when you drive in "ECO" mode.
I had a C7 with a manual, so it was not an issue. My wife had a C7 with the automatic, so we bought a Range AFM device. It plugs into the OBD-II port underneath the steering wheel. It prevents the engine from going into V4 mode no matter what. I highly recommend this if you have a C7 with the A8, particularly if you intend to keep the car for a long time.
Drifting
Joined: Jul 2016
Posts: 1,910
Likes: 1,167
From: Keswick, Virginia
It drove just fine. No more of that annoying 'thud' when it went in and out of V4 mode.
The highway fuel economy of a C7 is excellent - no need to try to squeeze out 1 more mile per gallon by running four of your cylinders dry.
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Drifting
Joined: Jun 2015
Posts: 1,855
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From: Lagrange KY
Melting Slicks
Joined: Oct 2022
Posts: 2,800
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From: Phoenix, Arizona
2025 C7 of the Year Finalist- Unmodified
2024 C7 of the Year Finalist - Unmodified
Drifting
Joined: Jun 2015
Posts: 1,855
Likes: 694
From: Lagrange KY
Melting Slicks
Joined: Oct 2022
Posts: 2,800
Likes: 2,344
From: Phoenix, Arizona
2025 C7 of the Year Finalist- Unmodified
2024 C7 of the Year Finalist - Unmodified
Team Owner
Joined: Jul 2004
Posts: 28,466
Likes: 3,288
From: Hartford WI
Team Owner
Joined: Jul 2004
Posts: 28,466
Likes: 3,288
From: Hartford WI
Melting Slicks
Joined: Feb 2018
Posts: 2,173
Likes: 1,041
From: North Texas
No need to 'pull out' the Diablo I3.
Once tuned, it stays and does not effect emissions testing and GM can't tell. But I'd tune it back to stock before any engine work at a dealership.
Once tuned, it stays and does not effect emissions testing and GM can't tell. But I'd tune it back to stock before any engine work at a dealership.
Team Owner
Joined: Jul 2004
Posts: 28,466
Likes: 3,288
From: Hartford WI
I kicked it out a couple of times. Didn't want to be "3rd time lucky" and have to replace the OBD port. Figured it was a sign.
Race Director
Joined: Apr 2014
Posts: 10,430
Likes: 1,727
From: North Texas
Team Owner
Joined: Jul 2004
Posts: 28,466
Likes: 3,288
From: Hartford WI
Race Director
Joined: Apr 2014
Posts: 10,430
Likes: 1,727
From: North Texas