so i have a problem and i'm absolutely stumped, i had my engine recently rebuilt and ever since i have nothing but compressor surge, i never did before but now it's very apparent, i have tried multiple different vacuum sources and all of them result the same, i have a blitz DD blow off valve, i took it apart and made sure it worked properly and everything, plunger works fine, lubed it up with some industrial silicone lube and put it back onto the piping, it's nearest the turbo....

i have a profecB specII installed and even used that vac source because i KNOW it's proper, the lines fit snug and everything, i even set up my rev limiter and held it there a bit to even create boost while a friend watched and NOTHING, i even made 12psi and it still didnt blow off....

i'm stumped, i have used many different sources that should be proper, the current one i'm using is off the back of the intake manifold and ofcourse it does not work, it's spliced to my FD pressure sensor but other then that it's a direct line....

any idea's guys?, it worked before and now it doesent, when i took it off it took alot of force to get the blow off valve's plunger or piston to move, is that a sign that the blow off valve is pooched, or?, i loosened the spring quite a bit and still nothing....

help!...

( this is on an 1989 S5 Turbo by the way, i'm running a BNR3 60-1 turbo aswell )....

 

Do you have a vacuum hand pump? Apply ~15 inHg in vacuum to the bov and see if it opens. I'm going to guess that it won't. Put the stock bov back in or replace the thing with a new aftermarket one. If you watched the thing not open after letting off from full throttle, it's not working...

 

yeah i was pretty much at full throttle on the rev limiter set at 3500rpm, made 12psi, NOTHING, no movement apparently....

and like i mentioned, when i took it off and tried to compress the piston by hand it was severely hard to move, i couldnt understand how a little vacuum source could move it....

 

ahhhh, just swapped blow off valves and made sure there was no leaks at all....

any idea guys!?..

 

they have adjustment screws on the top for a reason. keep adjusting it.

my blitz SS came off a different car that pulled more less, and mine would just barely be open on its own, AT IDLE!!! i had to tighten it down a bit so it didnt stay open all the time. if your BOV is new, you still need to set it up. if it is used and came off a different car, the same still applies.

 

I've had very good luck with drilling and tapping the ACV blockoff plate. I used to compressor surge on my Greddy Type-S. I tapped my blockof plate and hooked it in there, and then I tightened down the adjuster almost all the way and it still blows off and can hold 21psi.

 

it's a used blow off valve, i adjusted the screw all the way out so it should be loose but still nothing....

i can see it quiver ever so slightly when i revv it in the engine bay and make a couple PSI but thats it....

then again i'm probably seeing thing with wishful hopes, lol....

which block off plate is the ACV plate again?...