SR Won't Boost Over 6psi

[bigjacsoc]

I had a manual boost controller for a while and I was able to get the boost up to 8-9psi but wouldn't go any lower or higher no matter how much I changed the MBC. I even took the MBC out and ran it stock and only hit 6psi.

I figured my MBC crapped out and just got a GReddy Profec B Spec II all hooked up correctly and at 0% it boosts to 5.9 and at 20%, 35%, and 40% it hit 6.2psi which is a negligible difference.

WTF? Any answers? Anyone had this problem before?

[bigjacsoc]

I had a manual boost controller for a while and I was able to get the boost up to 8-9psi but wouldn't go any lower or higher no matter how much I changed the MBC. I even took the MBC out and ran it stock and only hit 6psi.

I figured my MBC crapped out and just got a GReddy Profec B Spec II all hooked up correctly and at 0% it boosts to 5.9 and at 20%, 35%, and 40% it hit 6.2psi which is a negligible difference.

WTF? Any answers? Anyone had this problem before?
http://240atlanta.com/forums/images/vblue/misc/progress.gif

[ultimateirving]

get a new wastegate actuator the springs wear out after time, had similar trouble. put a new WGA on and it works like a dream. seeif that works.

[bigjacsoc]

I figured this is what could be doing it. Does anyone know if I vacuum leak would do it? I mean there was no difference between 0% and 40% in boost. I have pressure checked all vacuum lines and coupler, only thing that could be causing a leak is something stupid like a bad gasket, or something with the stock recirculating BOV and SMIC.

[bigjacsoc]

Bump why is this message not long enough?

[JayZeeSILVIA]

sounds like a bad wastegate spring

[bigjacsoc]

Bump. Any other ideas?

[Kingtal0n]

Bump. Any other ideas?

boost comes from the turbine being spun quick enough to spin the compressor quick enough to accelerate air enough to generate a "backpressure" as air molecules compress against each other as they try to cram into the cylinder/intake/plumbing/intercooler/turbo outlet.


So boost problems can occur for many reasons:
A damaged turbine
A damaged compressor
A boost leak
A bad actuator / poor wastegate signal

the boost leak problem also "occurs" when the compressor runs out of "breath". So for instance, asking why your t-25 cannot hold 15psi of boost at 7000rpm is not a "boost leak" problem (where it is out of compressor actually).

So from easy -> hard check the actuator, check the vacuum routing and boost controller lines, then check boost leaks, then examine the compressor wheel, and finally... the turbine.

[Vatche]

was your car working fine before all of this. you might have your vacuum for the actuator incorrectly setup