AFM annoyance or longevity concern?
Thread Starter
Pro
Joined: Mar 2007
Posts: 514
Likes: 31
From: Corinth, TX
AFM annoyance or longevity concern?
Have a 22 C8, and hear lots of gripes about AFM on the C8 and how to prevent it from engaging. On my 22 It is basically invisible other than the V4 in the display. My question is around is there a mechanical reason to not want to be in V4 mode? I can say that it is far improved from what I had on my C7 ZO6. Any thoughts?
Le Mans Master
Joined: Jun 2005
Posts: 5,037
Likes: 520
From: Texas
Personally, I think it is a "sports cars shouldn't run on 4 cylinders" thing. It's been invisible to me as well. I'm certain if GM disabled the light, 2/3 of the folks that hate it would not notice it anymore.
Only time I didn't want it on was the first 500 miles. After that, I had no issues with it.
Only time I didn't want it on was the first 500 miles. After that, I had no issues with it.
Pro
Joined: Jul 2021
Posts: 694
Likes: 617
From: Crosslake, MN
AFM is refined and not an issue. Show me documented AFM failures in the past couple years on any GM vehicle. They had problems when it came out but that was a lot of years ago. Keeping it from going into v4 didn't prevent the failures in the early years.
Instructor
Joined: May 2010
Posts: 182
Likes: 49
Have a 22 C8, and hear lots of gripes about AFM on the C8 and how to prevent it from engaging. On my 22 It is basically invisible other than the V4 in the display. My question is around is there a mechanical reason to not want to be in V4 mode? I can say that it is far improved from what I had on my C7 ZO6. Any thoughts?
Melting Slicks
Joined: Apr 2021
Posts: 2,756
Likes: 2,323
From: Simi Valley, CA
2022 C8 of the Year Finalist - Modified
Melting Slicks
Joined: Aug 2022
Posts: 2,784
Likes: 3,566
He's referring to the many aftermarket catbacks that don't have AFM valves but instead just have simulators to avoid a CEL. You won't get a light but it sounds funky when the car goes in and out of 4cyl mode. Borla and Corsa are the big ones that offer all 4 valves, the rest of the big names (Soul, Fabspeed, AWE) all just use sims.
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Race Director
Joined: Jan 2014
Posts: 10,709
Likes: 7,101
From: Fulshear, TX
GM did a good job with it on the C8, big improvement vs. the C7 M7 as it's much smoother and more seamless now.
I have headers + cats + Borla and still don't mind it on the C8, and in fact enjoy saving a little fuel on long roadtrips as this is our best MPG car!
I have headers + cats + Borla and still don't mind it on the C8, and in fact enjoy saving a little fuel on long roadtrips as this is our best MPG car!
Melting Slicks
Joined: Apr 2021
Posts: 2,756
Likes: 2,323
From: Simi Valley, CA
2022 C8 of the Year Finalist - Modified
^^^ THIS. I get about 14 MPG around town with the way I drive and I appreciate the 23+ MPG I get on highway trips. I think AFM is partly responsible for that. I know a lot of non-Z51 cars do much better than that.
Safety Car
Joined: Mar 2010
Posts: 3,787
Likes: 332
From: Wickenburg, Az
I'm getting 20.5 mpg around town presently due to the V4 mode.... we do have road construction going on on Hwy 93 so that does keep the speed down but I am impressed given the V8 platform. Really surprising.
Melting Slicks
Joined: Aug 2022
Posts: 2,784
Likes: 3,566
I typically return 22mpg in mixed driving that is probably 60% what you'd call 'around town' and the rest rural two lanes with 55mph speed limits. Since dropping a whopping 50 pounds of rotating weight off the wheel/tire/brake assemblies, I can touch 30mpg on a highway trip now. I'm sure that is due in no small part to the AFM. This Corvette gets better MPG on the highway than the last 6-cylinder 3-series BMW I had for the wife (2011 328i with the 3.0L inline six and 6-speed auto). That thing would get 29mpg in ideal conditions. Kind of remarkable.
Melting Slicks
Joined: Aug 2000
Posts: 2,416
Likes: 1,189
From: Early 2020 Z51 Coupe, Original Owner, Ahwatukee Foothills, AZ
Sounds as though AFM is a big improvement from the past, but personally cannot stand it. I get it, a lot of C8 owners just want the cruise around in the slow lane and enjoy the mpg.
Having my PCM sent in to HP Tuners in just a week for the Global B E85 Flex Fuel Dyno tune, and happy to report that my C8 will forever be finished with the V4 nonsense.
Having my PCM sent in to HP Tuners in just a week for the Global B E85 Flex Fuel Dyno tune, and happy to report that my C8 will forever be finished with the V4 nonsense.
Drifting
Joined: Sep 2020
Posts: 1,453
Likes: 1,194
From: DFW
Sounds as though AFM is a big improvement from the past, but personally cannot stand it. I get it, a lot of C8 owners just want the cruise around in the slow lane and enjoy the mpg.
Having my PCM sent in to HP Tuners in just a week for the Global B E85 Flex Fuel Dyno tune, and happy to report that my C8 will forever be finished with the V4 nonsense.
Having my PCM sent in to HP Tuners in just a week for the Global B E85 Flex Fuel Dyno tune, and happy to report that my C8 will forever be finished with the V4 nonsense.
Instructor
Joined: Nov 2023
Posts: 191
Likes: 120
From: Atlanta area
I feel like when it is in V4 mode, when you give it some gas, there is a tiny bit of lag as the other cylinders engage and start firing... I like the added Econo,y when cruising on the highway... was getting 28.1mpg last time with it on...
But I figure I bought a V8 sports car and so I just set up Z mode with Track engine setting to keep it in 8, and if I am cruising down the interstate I drop to Touring mode....
But I figure I bought a V8 sports car and so I just set up Z mode with Track engine setting to keep it in 8, and if I am cruising down the interstate I drop to Touring mode....
Melting Slicks
Joined: Nov 2012
Posts: 3,163
Likes: 686
From: SUFFIELD CONNECTICUT
Sounds as though AFM is a big improvement from the past, but personally cannot stand it. I get it, a lot of C8 owners just want the cruise around in the slow lane and enjoy the mpg.
Having my PCM sent in to HP Tuners in just a week for the Global B E85 Flex Fuel Dyno tune, and happy to report that my C8 will forever be finished with the V4 nonsense.
Having my PCM sent in to HP Tuners in just a week for the Global B E85 Flex Fuel Dyno tune, and happy to report that my C8 will forever be finished with the V4 nonsense.
Melting Slicks
Joined: Nov 2012
Posts: 3,163
Likes: 686
From: SUFFIELD CONNECTICUT
BS, there are a bunch of us that feel and hear the useless V4 mode going in and and out. Do not need it, do not want it, The LT1 will be a happier engine with out it..
Former Vendor
Joined: Aug 2011
Posts: 1,307
Likes: 115
From: Tampa Fl
St. Jude Donor '12
Corvette Tuner in Tampa
I see more problems in the trucks than I do in the Corvette - Camaro family.
GM has gotten a lot better at making it not as noticeable.
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GM has gotten a lot better at making it not as noticeable.
EMAIL: Tuning@TampaTuning.com
Website >>> https://shop.tampatuning.com/
CHECK OUT MY SHORTS : https://www.youtube.com/@tampatuning/shorts
Street Performance Tune Package starting from $390.00
Instagram: TampaTuning
Corvette tuner in Tampa
Racer
Joined: May 2018
Posts: 269
Likes: 58
From: Auburn WA
I ran with a Range Engineering plug in on my C7 A8 for over 7 years with it never in V4. I also had the transmission oil changed to the newer version although I’d never had torque converter clutch problems. When I traded the’16 for my ‘23 I pulled the Range out to put it in the ‘23. Have not done this yet. Has anyone had experience with the Range in a C8 Corvette? It just seems that a V8 car like Corvette should run on all 8 cylinders.