Lots of Vacum but no Boost

[Trampisjr]

Hey guys,
Hope you the summer is/was going good for you all.
I have a quick question and hopfully this is a common problem, but Its killing me...
My car is building plenty of vacum (20lbs) but no boost, also it dosnt have much power to the wheels.
The turbo is fine, and there is no boost leak anywhere I can find.

Anyone have any idea?

 

[kenamond]

FYI, vaccuum is usually measured in in-Hg, not psi, and it's impossible to have a vaccuum less than 14.7psi at sea level.

Check your wastegate. It might be stuck open. If the WGA arm popped off the WG lever or if the arm is binding on a heat shield or if the WG lever/shaft is "walking out" of the housing, all could cause the WG to stick. If it sticks open, the turbo will not spool well or at all. You can check all of this out pretty easily.

If you're confident that the turbo is okay (spins freely, no major in/out shaft play), and you have no boost leaks (make sure you are doing the test correctly), that's all that comes to mind for me. Did you change anything right before this started happening? Have you been able to boost before this?

 

[Trampisjr]

I "think", not sure till tomorrow when I can see better, but my timing belt may be off by one tooth.
Would this cause it to do this?

 

[kenamond]

I wouldn't think that would keep the turbo from building boost. I'd still get the motor properly timed, though. As long as exhaust is going through the turbine in sufficient quantity, you should be building boost. If the WG is open, the exhaust could be bypassing the turbine. That's why I think you should check that the turbo is not shot and that the WG is not stuck open.

EDIT: I guess another possibility is that the exhaust manifold is leaking HORRIBLY. Not as likely, but you could check that the mani isn't hanging loose on the head or something.

 

[thewombis]

This just happened to my t25 a few days ago. Turns out the turbo just pretty much exploded, my boost gauge would not go above 0, so i gassed it and built 5 psi. Next thing I knew i had a giant cloud out the back, and lost oil pressure. All my oil ended up going into my exhaust, or (most of it) ended up in my IC pipes...what a surprise that was!

 

[dsmnthamakin]

That just happened to me about 4 months ago but my waste gate actuator arm broke off. when i went to check if my actuator was working the arm came off.