You have a boost leak at a coupler interface. Happened to me, boost would climb up to a certain threshold then dump out once reaching a breakpoint. Do a boost leak test and find the suspect joint. Reseat your couplers and get better clamps if that's an issue.

Also, I would undo what you did to the IAT sensor and coupler. You've just added another leak point by punching a hole in the coupler.

 

OK I swapped to a new coupler between tb and the black box, to get rid of the iat sensor hole in it. The coupler between the blower and the box was all oily inside and slippery so I cleaned it up and re tightened. Tested it out just now : I got up to 8 psi, a bit better than the 7.2 before but it dropped again. Do you think it's possible that it is one of the bov hoses or the smaller hoses coming from the valve cover? Could the SOS bov be faulty and leaking air after a certain psi) I forgot how those things work. I got some t-clamps coming next week for the main 2 couplers To make sure it's As tight as possible. I really thought the oily one would be the fix, maybe I didn't clean it and tighten it enough? I also do not see a sign that it slid out like I could see before resetting it.

 

Yes...BOV could be the problem...Another member had a similar problem and the BOV was the culprit.

https://m.youtube.com/watch?v=lI9rJoNzNVc

 

Invest in a boost leak tester, otherwise you're second guessing yourself and blindly replacing parts. Also, there should not be any oil in the system - looks like your blower needs to be rebuilt.

 

So I took off the intake elbow. That was oily. The coupler after the blower was really oily again. Cleaned everything. Got the new t-clamps installed. Added my catch can between the valve cover and the intake elbow. Thanks for the help guys. I agree about the boost leak tester. I will have my shop check it. I'm trying to have the car together before the dragon event this weekend, that's why I haven't had time to get it to mechanic. I'll put the blower rebuild option at the bottom. In my experience in cars I have found its most common to have the cheapest part fail much more often than the expensive one. My guess is that oil spitting out from the valve during my track time got into intake hose and collected at the bottom of the coupler and is causing it to leak there.

 

***Solved***. The new intake filter is too restrictive. I added an intake pipe going through the headlight and down to the brake duck vent area in the bumper. As soon as I swapped back to the old filter I got all my boost back. The filter I used in the bumper was the hks style sponge mushroom. I assume this filter type just doesn't flow as much. So thanks everyone for your help, now I can dyno. I still have the oil problem, I will evaluate that separately. I don't think the extra elbows are the problem, so I'm still going to run the filter in the bumper, just need a different on in there.

 

Should always put the largest filter you can fit (or modify to fit) on the car.

 

Thank you. It's specifically the sponge material that is restrictive not the size. I got a brand new KN style filter and right now it's on the short stack and it pulls nice. I am going to try again to fit it into the bumper space to see if the boost is same. I'm also going to test temp difference between the setups.