I've been having this problem ever since i go over 10psi. I have the turboXS dsmbc. When i set the lower boost to 10psi or under it will hit the boost level and stay there. Once I up the boost any it will go up to that desired level then it will drop off. Lets say I set it to 15psi. It'll drop to around 13psi. When i set it to 14 it'll drop back to around 10-11psi.
I have my vacuum lines hooked up as follows:
top port wg: open
side port wg: connects to boost controller
boost controller: connects to compressor side of turbo

I've seen other peoples setups and they have there's ran differently so i tried that.
top port: connects to boost controller
side port: connects to vacuum manifold
boost controller: connects to compressor side of turbo
This just led to the boost to rise up alot slower than the other way and it just kept going till it hit boost cut

btw...My setup is in my sig

 

ttt

 

Sounds like your wastegate spring is too small.

 

its a .5 bar spring. I was told u can boost up to double the spring with a boost controller. .5 bar is like what 7psi so i dont see why i can't run more than 3psi more w/o it losing boost pressure.
I've heard stories about the turboXS rfl that i have. I'm going to try to add the washers that came with it to see if it helps any.

 

just tried the washer thing and that didn't work out too well. I just found a hole in my dizzy cap the hard way. It zapped me while i was tried to rev the car up and put my hand near the bov. omg...i hate this car.

 

ttt one more time

 

Spring might be too small, as mentioned above... but the only other thing I can think of is changing your boost source from your turbo to your intake manifold. You will easily squeeze a few more pounds out of your setup that way b/c the wastegate will see lower pressure from the IM due to the pressure drop from both the restriction of the intercooler and the fact that the cooler air is at a lower pressure...

Matt

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Johnyquest &raquo;</TD></TR><TR><TD CLASS="quote">Spring might be too small, as mentioned above... but the only other thing I can think of is changing your boost source from your turbo to your intake manifold. </TD></TR></TABLE>

i'll try that this weekend.