Got my APS BOV today... installed it correctly (sideways, with the nipple for the hose pointing downwards), but the thing runs like crap. Out of the box the adjustment screw was nearly flat with the locking nut. Loosened it to about 2.5 turns from when the screw actually touches the piston, didn't seem to change a thing.

At partial boost it runs like crap, when I let off on the gas the thing studders and goes "TSUN tsun tsun...." for lack of a better description. It seems to idle ok, but the driveability is no good? This is coming from a Greddy TypeS with single spring mod.

 

Okay, I've tried everything from really tight to really loose, and nothing seems to fix the problem. My ECU has been flashed with the Greddy BOV on it, I don't imagine that should be a problem but it would appear otherwise. All my lines look good, they're clamped down, it's just not working... either I've got a defective valve, or my car hates the APS BOV.

 

Ok, so with both BOVs off the car, I tried comparing the amount of pressure it takes for the valve to open back to the intake. Here are some things I discovered:

-the amount the piston travels on the APS is probably 2-3x that of the GReddy
-the amount of force it takes to move the piston inside the APS BOV is probably about 2x as much than the Greddy

When playing with the APS BOV, the piston seemed "sticky" for lack of a better term. The movement of the piston was not very smooth, and it seemed to take an extreme amount of effort in my case, to move the piston (vs moving the Greddy diaphragm - remember, it's got the one spring mod). I am assuming the studdering I get is a result of surge - the BOV isn't doing it's job, and it's not opening up properly. So instead, the pressure goes right back into the compressor wheel. In this case, loosening and/or tightening the adjustment screw don't seem to do any good.

That being said, unless can provide some good suggestions, I'm putting the APS BOV up for sale. Any takers?

 

Okay, just kidding.

I put my Greddy BOV back on, and now it's having the same driveability problems as the APS BOV. What the heck is going on??

 

definately sounds like compressor surge. I'd pressure check the whole system to make sure the bov has enough vacuum to open up the valve.

 

I think I lost a restrictor pill somewhere along the way, at WOT my car now boosts like 30psi. Where are the two restrictors supposed to be? Is it like this?



And with the XFlash:



I have a Greddy FMIC that doesn't have a turbo discharge nipple, so I'm tapping into the BOV line:



I know this setup works because this is what I had when Shiv custom tuned my car a couple of weeks back. However, at that time I had lost a restrictor so I was boosting 30psi... Shiv put in a restrictor somewhere and it fixed the problem - I'm guessing that's the restrictor that I lost.

 

Check all of your vacuum lines. It sounds like you have knocked one of them off or something. If the wastegate and the bov aren't getting a vac. signal neither will open correctly.