BOV will not operate

BlackMetal

Active Member
First of all anyone with the intention of turning this into the usual BOV argument, leave now. Have respect for which parts I want to install on MY car. With that out of the way...

I have an SSQV knockoff BOV.

-it WAS working fine when installed maybe 2 years ago
-suddenly stopped operating at some point
-switched to a FMIC, put it on the pipe between turbo and IC, didn't work
-now I'm back to SLIC with regular up-pipe, it's installed close to the throttle again, still isn't working
-adjustment screw is all the way "loose"
-it's hooked up to a fresh high quality silicone vacuum line that's shared with the boost gauge, if the BOV wasn't getting vac/boost then my gauge wouldn't be reading either
-I tried a different "Style" BOV a while back and that didn't work either
-BOV has been inspected, diaphragm is not ripped, valve is not seized


This is one of those things that doesn't make sense even when it seems all variables are accounted for. Why is a valve not opening when it's getting a healthy vacuum source on a car running plenty of boost? Someone will probably say "stop buying knockoffs" but when you take these things apart and realize how simple they are, I don't think the brand name is the problem I'm having.
 
Just for giggles have you tried a different port? I know the gauge wouldnt work, but you should still try.

BTW I run a knock off on my car and it works very well. Well enough that I will be running a second one on the same car.
 
I've been considering either trying another port or unhooking the gauge and giving the BOV a vacuum line all to itself, just to see if that helps.

I'm sure something stupid like that is going to end up fixing it, because like I said, all other logical answers have already been explored.

EDIT- Then again, the BOV worked when I first installed it, and I know it was spliced into a line then too...
 
When it's off the pipe, can you push the valve open? Maybe it seized up at some point? EDIT; never mind, see in your OP that it's not seized.... Is there only one port to hook the vacuum hose up to? My ATR has two...
 
When it's off the pipe, can you push the valve open? Maybe it seized up at some point? EDIT; never mind, see in your OP that it's not seized.... Is there only one port to hook the vacuum hose up to? My ATR has two...

Yeah I can move the valve with a little bit of a push with my finger. I took it all the way apart today, checked the seals and diaphragm, all that stuff is fine.

And yeah with the design of this valve there is just one port to hook to vacuum and it used to work installed the same way it's always been.
 
Any other ideas?

get a real tial Q :) and be done with it, theres 1 or 2 tial tech on this board that will help with any problems. or you can call their tech numbers too.

"Why is a valve not opening when it's getting a healthy vacuum source on a car running plenty of boost?"
that is the question, only thing to do to check would be buy another same brand knock off then compare and contrast.
my guess would be corrosion or valve failure, I have seen it on china wastegates personally but never on a copied bov,
just my 2 cents.
 
Yeah was considering just buying another one but at $50 it's still not chump change to throw away.

Corrosion where? I've taken it all the way apart, should have snapped pictures to go along with this thread. Valve failure? All evidence seems to say it should work.

Plus like I said I tried another type of valve, a type S or something, and that one wouldn't open either.

It's not the end of the world, I can live without one, it's more that I want to understand what's going on.
 
borrow a mighty-vac or similar product - attach it to the vacuum port and manually check valve operation.... you can use this to set the pre load as well...
 
I guess I could try the might-vac.

Can't afford an authentic $200+ valve right now.

It rained today so I didn't get a chance to hook it up to it's own vacuum line without sharing the boost gauge, but I don't think that'll do it.
 
So, when you are at say 15lbs of boost, and you let off the throttle completely, you get no "whooosh", just the familiar flutter/sneeze sound? My BOV sometimes works right and other times I still get the flutter (like lower boost). FWIW, I have mine hooked to the hose that usually goes to the charcoal canister, I leave the one-way valve with a small piece of hose attached at the canister and when smog rolls around I just pull the hose off the BOV and attach it right to the one-way valve. Don't have any of those one-way valves located inline anywhere that would interfere do ya?
 
Yup all I'm getting is turbo flutter. The SSQV makes a distinct sound and I know I'm not hearing it.

There's no check valves or anything accidentally left on the line. I just replaced all vacuum lines, I have a short line from the vacuum block, it T's off, one goes back to my boost gauge and the other goes a short distance to the BOV on the uppipe.

It's just frustrating because it makes no sense, I actually would have been happy to find a torn diaphragm inside.
 
Yup all I'm getting is turbo flutter. The SSQV makes a distinct sound and I know I'm not hearing it.

There's no check valves or anything accidentally left on the line. I just replaced all vacuum lines, I have a short line from the vacuum block, it T's off, one goes back to my boost gauge and the other goes a short distance to the BOV on the uppipe.

It's just frustrating because it makes no sense, I actually would have been happy to find a torn diaphragm inside.

With an authentic HKS SSQV BOV it comes with a check valve and it is recommended you run it from source around MAP sensor.... fwiw. i still have a check valve plumbed into my vacuum hose going to my BOV.
 
You might be onto something. If boost is allowed to build on the wrong side of the diaphragm, it has to overcome that before having enough vacuum to pull it open. I know it came with something to install in the line, I'm 99.999% sure that it was just a little filter to stop crud from getting into the BOV though. If it was a check valve I certainly didn't even check which way it was installed before I put it on. But then when I moved the BOV around and messed with it, I took that out of the line.... maybe that's when my problems started????

I'm excited to hook it back up with that "valve" and see if it works again but I'm used to being disappointed every time I think I've got it figured out.
 
I thought I knew exactly where that little filter (or check valve) was at, but I went to look and I can't find it. So I guess it'll remain a mystery whether that was a checkvalve or not.

I did try it with one of the stock checkvalves in place that I had laying around, it did leak a little bit in the wrong direction but should have been an improvement over no valve at all, BOV is still not opening...............
 
I thought I knew exactly where that little filter (or check valve) was at, but I went to look and I can't find it. So I guess it'll remain a mystery whether that was a checkvalve or not.

I did try it with one of the stock checkvalves in place that I had laying around, it did leak a little bit in the wrong direction but should have been an improvement over no valve at all, BOV is still not opening...............

you try the mighty-vac yet???
 
You have to get one not that expensive Harbor Freight prob. has them cheep you need to know if the BOV you have is holding vacuum if it's not then it's bad diaphram is moving just leaking internally
 
Haha yeah I already looked it up at Harbor Freight, $20. Maybe I'll go in a few days.

I just removed it from the car and messed with it again. I forgot how the piston that opens actually has two stages, the little pintle in the middle opens at low boost and the big piston opens for more air. I noticed the small valve was a little "sticky", spun it back and forth and got it to free up, maybe that will show an improvement.
 
Freeing up the little valve didn't help. Also stopped and removed it from the Tee, left the boost gauge unhooked, and gave the BOV it's own vacuum source off the vac block. No change.
 
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