Hey guys I installed a manifold and divorced 02 on my evo ix. this was probably the worst install experiance i've ever had, and i have a ton of experiance with installing manifolds and what not. It was just one thing after another.
Any ways the issues:
1.broke a bolt off in the turbo, I drilled it out and replace it with a bolt/nut
2.could not one bolt tighten between the manifold and turbo
3.Absolutely could not tighten a bolt to the stud on the 02 housing. Actually no no nut would fit on!!
4.could not get the o2 sensor out of the housing. I used the rear 02 sensor and changed the connector.
Even with these problems car should still boost. it drives perfect, just wont boost ....Please help.

 

You should have used PB Blaster.

Sounds like there is a leak between the manifold and the turbo's hot side, not allowing the waste gate to properly function off exhaust gases.

Retrace your steps, obviously wherever you cannot get bolts to tighten is where the issue is.

 

There's no preload on the wastegate when you installed it.

 

check your wastegate and your vac lines

 

check wastegate preload and pre-turbo exhaust leaks will get you nowhere fast

 

What manifold, and what divorced O2 are we talking about here?

 

definitely no preload, which would mean you probably have a bigger gap than initially thought when you put them back together and couldn't seal. I would take off the intake, just to make sure prop is free spinning. then seperate the downpipe so not to obstruct O2 and begin loosening each major part going up to mani, one piece at a time. Basically in the end everything is still together, but loose, so you can slightly move each piece independently. Check to make sure wastegate is operating properly. Now tighten them back up from mani back down again. The sequence honestly will depend on those areas you said bolts wouldn't fit. you may have to go to hardware store and get a smaller not (12-11mm) depending. anyway, good luck, hope you fix it..

Oh yeah, make sure to check the nipple coming off wastegate to Boost solenoid as well, if its bent and closed, WG won't work properly.

 

Can you hear it spool at all? You might have dropped something in the turbo preventing it from spinning, not the case if your making 2 psi though. Unless your really not and your gauge is off by 2 psi.