Trouble Boosting...Frustrating

Sounds to me like the wastegate is either stuck partially open, or it does not seal all the way (probably due to shitty porting if that's the case).

Have you done a boost leak test?

Like above, do a leak test. If that yeilds you no result's then pull the actuator rod off of the wastgate "arm" and try to swing it back and forth. If you can't if obviously stuck. Is the car running ok? Dose it bog, or miss? Or you just Can't boost past 15psi? What type of MBC are you using?

yes I have done the boost leak test many times, and there are no leaks. I'am using a turbo xs manual boost controller and have even changed the boost controller twice to see if that was it and its not. Even with the wastegate hose pulled still wont boost over 15-16psi.

I havent checked the wastegate flapper, it could be stuck open. If thats not it then I'm completely stumped.

How would I check the wastegate? do I have to pull my o2 housing?

try another boost controller, a freind of mine had a turbo xs one and I know he had problems with it mostly because it a bleeder type controller, try a ball and spring I think it will fix your problem..

I have tryed other boost controllers and it doesnt make a difference. the boost controller works fine....

my car has "trouble boosting " sometimes too.. its bone stock and sometimes i'll get on it and the boost gauge will read 10-12psi but the car doesnt go anywhere.. then i'll let off and try again and it pulls hard.. weird stuff lol.. no leaks or misfires either..98 gst

I hate to bump my thread, but I really have no idea whats wrong, any other ideas?

HELP!! anyone have any ideas? I tryed wiring my wastegate shut, but then I only got 4psi? which makes no sense...

its a new evo3 turbo, no shaft play, as far as I know, no wastegate problems. It wont boost over 15psi anymore, and I have no idea why. its not slow by any means, but I miss being able to turn up the boost sometimes.

Is your boost reference line hooked up to your BOV? My car used to pop it's reference line sometimes and then it would cause the BOV to leak and run low boost. Or maybe the BOV itself is leaking?

yes its connected, I could always set my BOV a little harder and try that.

A couple of reasons why you may not be able to boost past 15psi:

1: The ECU may be pulling your timing due to spark knock
2: Your piston rings and/or your valves may be severely worn, causing a loss in
compression.
3: Improper connection of wastegate/boost controller/BOV
4: Exhaust system restriction, such as a plugged catalytic converter or muffler

I would bet money on #3; everytime i've worked on a dsm that wouldn't boost properly, the boost controller was hooked up incorrectly. Use the following link to ensure that your B/C is set up correctly. http://www.belitski.com/vfaqhallman.html
(link provided via www.vfaq.com)

I'm positive my BC is hooked up right.

if ur cat back has a whole in it would it effect anything? j/w

It would help. Not harm. Less restriction.

Okay, lets attack it from this direction then. Was anything done to the car recently that seemed to cause the issue? I'm pretty sure that this isn't the case since you would have either changed it back or at least noted it here, but it's worth a shot anyway. Next, I would log a run to see what's going on. Check for things like timing being pulled and such. Post up your results so we can diagnose further. Good luck.

If you had a weird exhaust leak it could hinder the system and cause weird misfires. I've seen this plenty of times.

I have also had a Cat that was clogged, but you could hear it rattle inside. I could not generate more than 5psi of boost with it clogged/broken up inside.

Still it sounds like you have a problem with your wastegate there.

Ok, I know for SURE there are no exhaust leaks or boost leaks, and I dont have a cat, its 2.5 inch from the turbo all the way back. Thanks for all the ideas guys, I'm still leaning towards a wastegate issue of some kind.

Could the problem be just that I have an automatic? Some people have told me that an auto cannot push the turbo to boost as much as a manual.....is this true? I'm all out of ideas