I have an 05 Evo 8 and i have a backfiring problem. I have a HKS SSQV blow off valve, which is recirculated to fix the backfiring but it didnt do anything. I also have some small basic mods, and i am running on a factory tune. It usually starts backfiring around 4700rpm. Anyone have any ideas wat it can be?

 

boost leak. Check for boost leaks. Changin the spark plugs might help.

 

throw that blow off valve out,clean your mass air,and check your plugs!

 

if any of those "small, basic mods" you have is an intake or exhaust, you probably just need a retune

 

i had the exact same problem as u are having. brought it to the dealer and found out it was a clogged cat.change the plugs as well.

 

I would still get rid of the aftermarket BOV and put your stock one back on so your car will run better.