jmoz519":3o2o1bq7 said:
could it possibly be a stuck wastegate?
Just like no turbine wheel, an open wastegate will not let you get past 0psi
The good money is on a massive boost leak right in front of the turbo,
I cant think of anything else that could stop u going past 0psi as a leak at the throttle body/intercooler side (which is the next largest [volume] air leak spot) would still allow you to achieve upto 3psi as you reach the upper limits of the rev band, and the hissing sound would be a dead giveaway.
It may be as simple as the coupling hose has gotten old, stiff and brittle so even though you tighten the clamp it wont fully seal.
Get some new coupling hoses if yours are in bad condition, if they are soft, flexible and without cracks and cuts then i would just recommend you remove your intercooler, check there isn't a flood of oil inside the turbo compressor while the intercooler is off, then just put it back on.
The act of removing the intercooler is beneficial in 2 ways,
First it allows you to remove, clean and inspect the rubber coupling hoses for degradation,
Second it will allow you to put the hoses back on with a
confirmed seating so you know 100% that its not your problem anymore.
Just remember to tighten everything with a socket set and not a screw driver, most worm gear clamps have the Phillips head screw as an option but you can only apply limited torque before you start to strip the head.