[craigss50]

I have had an occasional backfire under full throttle since the car was new (now has 6500 miles on it). It occurs at high RPM at the shift point and at times is really loud. When it shifts or I shift it manually the backfire occurs and sometimes a miss occurs. I also noticed black smoke at that time. I took the car in to the dealer and they could not duplicate the issue and no codes were present. I took the service manager for a ride but it did not occur then either, probably because I had been doing a lot of full throttle before taking it in to analyze the issue blowing out any buildup.

I purchased a Range AFM delete because I am thinking unburned fuel/oil in the cylinders may be causing it. I noticed if I do several hard accelerations the backfire lessens and then goes away for awhile. I am hoping the Range AFM delete which prevents 4 cylinder activation will eliminate it. I do not want to put a catch can on for fear if the engine does blow one of these times it would not be covered under warranty. The Range AFM Delete can just be unplugged with not trace of it ever being there. Most of my driving is short trips which is not good for the engine but it is what it is. I am retired and my gym which I go to 4 times a week is only 1.5 miles away. Only once a week or so do I drive it for more than 5 miles so there may be a build up occurring. In addition I had the A8 shutter which some believe is cause by the AFM so it may keep my transmission/TC healthier. I also purchased a OBDII switch to cut current to the Range device to prevent battery drain which can be an issue if the car sits for a few days or so. Anyone else have this issue?

[kropscamaro16]

are you no lift shifting because if so it will do that

[craigss50]

It's an automatic so no.

[Jeb114]

Your hitting the rev limiter so the computer cuts the fuel to protect the motor when the rpm drops it returns to normal

[craigss50]

Originally Posted by Jeb114

Your hitting the rev limiter so the computer cuts the fuel to protect the motor when the rpm drops it returns to normal

It does it when I let it shift automatically.

[VinnAY]

Its backfiring...thru the intake...? I ask because there are quite a few that call things a backfire when it's just popping and gurgling, thru the exhaust and they're not prepared for the sound.

[squish72]

Are you maybe talking about this?
https://www.camaro6.com/forums/showthread.php?t=485869

[Glen e]

Originally Posted by craigss50

It does it when I let it shift automatically.

Correct, it was explained on the Corvette site that the ECU upon a full throttle shift will let off the throttle for a microsecond, which will build up some fuel and then when the power is back on it backfires… Normal…

https://www.corvetteforum.com/forums...post1596759935

[craigss50]

Originally Posted by VinnAY

Its backfiring...thru the intake...? I ask because there are quite a few that call things a backfire when it's just popping and gurgling, thru the exhaust and they're not prepared for the sound.

Definitely a backfire not popping or gurgling like when you let off the gas. I am surprised it has not blown out the catalytic converter.

[KMPrenger]

I don't know about your particular instance...not saying what you are experiencing is normal....no way for me to know.

But it is a fact that GM did design a slight backfire into the tuning for full throttle shifts with the A8...and its awesome.

[bullet3z]

Find someone with a automatic Corvette. Get them to do a full throttle pull. They sound amazing when they shift and you hear the backfire/pop of unburnt fule. The Vettes sound like a exotic sports car when they do it. My 6 speed SS will sometimes do it on a full power no lift shift or a really quick lift and shift.

[craigss50]

Originally Posted by squish72

Are you maybe talking about this?
https://www.camaro6.com/forums/showthread.php?t=485869

Thanks for these responses guys. Takes a load off my mind. I thought for sure something was wrong.

[Gunkk]

These auto cars make an awesome CRACK when shifting at the limit. The Z also kicks you in the kidneys

[breakskeet]

Originally Posted by bullet3z

Find someone with a automatic Corvette. Get them to do a full throttle pull. They sound amazing when they shift and you hear the backfire/pop of unburnt fule. The Vettes sound like a exotic sports car when they do it. My 6 speed SS will sometimes do it on a full power no lift shift or a really quick lift and shift.

My Z06 A8 does exactly this