i built a turbo setup for a friend on his v6 camaro and while out tunning we have this issue of a backfire/pop out the exhaust at 5 psi.

on the datalogs i notice as soon as it pops the wideband will read dead rich.
the afrs under boost are good 11.5 to 12.5,and soon as it pops it dips well into the low 10's. this usually happens in the 3500-4k rpm range we havent been taking the motor any higher then that due to this issue.

also i have a very limited advance curve right now 10* base and under boost were seeing about 16* total timing
im unsure if this would be not enough timing or a spark blowout issue , maybe one of u guys have experianced this and can help me out

if u watch this video and turn up the sound u can hear what it does , its near the end of the video about mid way threw 4th gear




btw the car has ac delco rapid fire plugs not sure on the gap yet but im going to check that today im pretty sure its around .030-035 though def going to close them up to .025-28 in a lil bit here

edit

forgot to add we havent made it past 1/2 throttle tuning yet so this is starting to show up around 1/2 throttle and even does it at a lil more then 1/4 throttle

 

The rapid fire plugs have that tiny tip that looks like i would get really hot, personally I'd be thinking change them out to an old colder looking plug.. and yea, gapped tighter. I had the same problem on my car and setting the gap from 35 to 25 made an incredible difference.

 

just looked up the rapid fires and they come pregaped at .045 and my friend dosent recall regapping them when he put them in.

so im going to pull them and regap them to .028 to start if that dont help im going to go back to the stock delco plug which is a r43tsk, which should work i run a r42tsk in my car ( turbo v6 camaro also) which is one heat range colder but i do experiance plug fouling on mine when i use my launch control and antilag systems so on his i think ill stick with the stock heat range

 

thanks man closed the gap to .025 and it runs perfect going to keep an ear out for detonation if i hear any im going to put convention plugs back in it

heres a clip after i closed the plug gap pull from 3rd threw some of 5th gear at 35% throttle we got out of it around or just over 100MPH