Yes I did, but what I did is not easily undone. When you know how the SSQV is supposed to work, it's easy to find out why it doesn't.
Picture of ssqv: (You will want to load it up in another window to see what I talk about)
http://www.streetunit.com/v/vspfiles/photos/hks_ssqv_diagrams_1-3.gif
Background/how it works: The way this bov works is pressure differentials. Chamber A on the diagram is where the vacuum pipe connects to, and it is the active chamber. Chamber B is the one that causes the valve to open and close, but it does not have vacuum applied directly to it, rather is gets pressure and vacuum from a small valve inside. That valve is both a check valve and a bleeder orifice, so the BOV closes after the pressures have equalized. It allows pressure to flow freely into chamber B, but restricts flow back into chamber A so the valve will open quickly and close slowly. Chamber C is where the boost lives, and when boost exists, it helps force the valve shut, resulting in a leak-free bov.
Diagram 1 is the BOV at rest, and rest can be either under boost or at idle. The check valve/bleeder has allowed chambers A and B to equalize in pressure so the spring is the only thing acting on the valve (boost also helps keep it closed). Diagram 2 is the beginning of a throttle lift, and it illustrated how the sequential part of the valve works, see as the smaller valve section is opening- relieving boost, and diagram 3 is after the valve has completely opened. As the pressure equalizes in chamber A and B (through the check valve orifice), the valve will begin to close.
Here's what I had happen. When I revved my engine, the turbo would make airflow, but when I released the throttle, the BOV would not do anything. Not open or move, nothing and surge was the result every time. I pulled the BOV apart and checked out all the moving parts, but everything moved correctly. When I went to test the check valve, I found that it passed air both directions easily. That was my problem- the check valve portion had failed. To counter-act this I circumvented the auto-close feature of the BOV since I expected the BOV to be throw away anyways.
What I did was drill a small (1/8-3/16") hole in the BOV body between chambers C and B, connecting them ( I drilled right below the shaft). What this did was to put pressure (atmospheric or boost) on the opening side of the diaphragm so when chamber A got vacuum, it would open every time and stay open until the vacuum went away. Another thing I had to do was cap off the hole drilled into the valve shaft, where the check valve would have been. All I did for that was get an M5 (can't remember pitch) acorn nut -closed top- to shut that passageway.
After all this what I got was a BOV that stays open all the time when at idle or when manifold pressure is negative. But when I go WOT and manifold pressure drops to 0 or goes positive, the valve shuts tight. The funny thing is that both of my turbos (CT26 and Comp 61mm) have air flowing out of the BOV at idle so I'm not so worried about sucking contamination into the system since the flow is always going out!
A lot of people might flame me for this, but I got my BOV for $10 and it does a better job than most other BOV's I have seen. And by "it's job", I mean keeping the compressor from surging. It even sounds cool as an added bonus!
