AFM Problems
Thread Starter
1st Gear
Joined: May 2021
Posts: 1
Likes: 0
AFM Problems
I have a 2017 Grand Sport 2LT and it seems to be having a slight missing problem and I wonder if it is due to the AMF? This is my second 2017, and my fourth Corvette, as I was in a major accident last month due to a drunken driver who ran me off the road and totaled my beautiful Long Beach Red 3LT Grand Sport. I don't remember having a slight missing problem with my Red Vette when it went from 8 cyl to 4 cyl! And I remember seeing the 4 and 8 cyl light up on the dash but I don't see on the cyl call outs this new 2017 White Grand Sport. So, I wonder does the 3LT show the cyl call outs but the 2LT doesn't? If any one can offer any help with this problem I would sure appreciate your thoughts.
I am actually thinking about having the AFM disabled but not sure if that would cause any warranty problems as I have heard there are products out there that can do that.
Thanks,
Dan F ..
I am actually thinking about having the AFM disabled but not sure if that would cause any warranty problems as I have heard there are products out there that can do that.
Thanks,
Dan F ..
Dazed Confused & Verklemp
Joined: May 2008
Posts: 1,398
Likes: 109
From: Naples, FL & Clear Lake, IA
Just buy a new or used Range OBDII plug in to keep your car in V8 mode all the time. It won't affect your warranty,,, but you can ask other forum posters if you aren't sure. You can also tune out the AFM. but that will affect your warranty.
Not sure what you are referring to regarding a missing problem? You should be able to set up your screen to show whether you are in V4 or V8 mode, as all C7's do this. If the miss is only in V4 mode then the Range will solve your problem.
If not your dealer hopefully can.
Not sure what you are referring to regarding a missing problem? You should be able to set up your screen to show whether you are in V4 or V8 mode, as all C7's do this. If the miss is only in V4 mode then the Range will solve your problem.
If not your dealer hopefully can.
Tech Contributor
Joined: Oct 1999
Posts: 41,043
Likes: 9,807
From: Charlotte, NC (formerly Endicott, NY)
I take it you have an A8 transmission. You can deactivate AFM by putting the transmission into Manual Mode. If you still have a misfire the issue may not be due to AFM. Another thing you can do is clean the throttle body and throttle plate. That usually smooths things out somewhat if the throttle body has carbon deposits.
You shouldn't feel any misfires or uneven engine operation when switching from 4 cylinder mode to 8 cylinder mode or from 8 to 4. I have an M7 Z06 which only activates AFM if I put the drive mode selector in Eco Mode. I can't tell when the engine switches between the two modes of operation unless I watch the display or when the exhaust is in permanent track mode listen to the exhaust volume. When the engine is running in 4 cylinder mode the exhaust valves close to reduce the objectionable sound. So when I hear the exhaust get suddenly quiet I know the engine switched to 4 cylinder mode and when it gets loud again I know it switched to 8 cylinder mode. Other than the noise level there is other physical difference I can detect that tells me the engine switched. It is seamless.
Bill
You shouldn't feel any misfires or uneven engine operation when switching from 4 cylinder mode to 8 cylinder mode or from 8 to 4. I have an M7 Z06 which only activates AFM if I put the drive mode selector in Eco Mode. I can't tell when the engine switches between the two modes of operation unless I watch the display or when the exhaust is in permanent track mode listen to the exhaust volume. When the engine is running in 4 cylinder mode the exhaust valves close to reduce the objectionable sound. So when I hear the exhaust get suddenly quiet I know the engine switched to 4 cylinder mode and when it gets loud again I know it switched to 8 cylinder mode. Other than the noise level there is other physical difference I can detect that tells me the engine switched. It is seamless.
Bill
Instructor
Joined: Apr 2020
Posts: 121
Likes: 17
From: Gilbert, AZ
I just tried this and it didn't work. My AFM values are still malfunctioning. Loud banging metal to metal (AFM baffles opening/closing really fast). I was in Track Mode.
Last edited by 17C7Z51; May 13, 2021 at 03:11 PM.
Tech Contributor
Joined: Oct 1999
Posts: 41,043
Likes: 9,807
From: Charlotte, NC (formerly Endicott, NY)
Bill
Instructor
Joined: Apr 2020
Posts: 121
Likes: 17
From: Gilbert, AZ
I was driving about 30 mph, but in manual (track) mode - 3rd gear. I didn't have the gauge changed over to see that, but I know what you mean. Let me do another test and see. I'll keep you posted.
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