I recently made some adjustments to my greddy profec spec ii ebc on my 05 evo viii and everything seems to be line with that. (holds 21psi consistently to about 6000 rpms. However I have come across a new issue that is scarin me a bit. When I'm in 4th or 5th gear at lower rpms like 2k-2.5k and I go full throttle my rpms will climb and after being in boost for about half a second I hear a loud bang and then they continue to climb. At first I thought it was a clutch problem, but the clutch is only 6 months old and it doesn't slip in any other situation. Also the rpms don't shoot up and fall back down it's just a loud bang noise. Any idea what this could be?

 

bad timing perhaps in that rpms...??? boost cut?? maybe make a video

 

is it when you shift?

 

My buddy had a problem like that, turned out to be a boost leak. But if your holding boost like you say, might not be the same.

 

It's not when I shift and it seems to hold boost no problem. One of my buddies said it would be that I'm running lean and fuel is entering too late. I adjusted the set on my greddy ebc and now the noise is gone, but when I drive normally my air to fuel ratio shows about 15, when I have the car under full throttle it goes down to 12.7 for as long as I'm on the gas. Any ideas?

 

I believe thats a little lean under full throttle, isnt it?