Blow off valve help
 

This may seem really stupid, but I am having the hardest time figuring it out. It seems so simple. My buddy gave me a eBay BOV off his WRX. I installed it onto the intercooler end tank on the hot side. It will not open, I have tried different line sizes, I have tried pulling vacuum from another source and still nothing, just compressor surge. I took it apart, cleaned it, and reassembled it, still nothing. This one is not adjustable, so I tried playing around with different springs, but can't seem to find the right spring rate. Should I just stop ------- with it and buy another one? I hoped to use the BPV off my 2011 WRX, but unfortunately the bolt pattern is not the same.


Suggestions?

Thanks,
Ryan

Where are you routing the line?

I had made a vacuum block that goes inline to the brake booster. I have my wastegate, boost gauge, and BOV coming off of it. But now the BOV port is capped and I have the source coming from one of the nipples right past the throttle body on the intake.

Picture of BOV? I had some trouble with a RFL knockoff a while ago, there was a rubber o-ring that prevented the valve from opening properly. I tried greasing it, using dry lube, all kinds of stuff, and nothing worked. I took the o-ring out and it worked fine forever after. It had pretty tight tolerence there considering what I paid, so it never even seemed to leak.

You should be able to put the hose in your mouth and open it. Varify it's working like that first.

Why in the hell are you pulling a wastegate signal from your intake manifold?

Why wouldnt I pull it from my intake manifold? I will snap a picture of it tonight.

Because then when you're climbing a hill at part throttle, the turbo is working super hard to get the pressure inside the IM up to your set pressure. The throttle plate won't let it, so it just works harder and harder. Just extra work is all. Some people like to source the waste gate signal there, but the generally preferred place around here is between the intercooler and the throttle plate.

That's what I just talked about with some local friends. My thought was pulling from over there would be better than pulling it from, say the compressor housing like I have seen a lot of people do. Because if you pull from there your source isn't seeing pressure drop from the intercooler. I didnt think about the throttle plate, we also discussed the fact of the pulling post throttle body it's putting vacuum on the diaphragm, which could wear it out sooner. So if pulling post intercooler but pre throttle body do you just put a nipple in the charge pipe?

Post intercooler pre throttle body! We've got to take the cars out soon.

Yes.

I'd definitely switch the wastegate source to pre-TB, this thread should describe it all:

https://www.miataturbo.net/diy-turbo-discussion-14/boost-sag-no-you-dont-need-ebc-47532/

Is the hole in the intercooler big enough? I had a bov that was drilled to the biggest size I could in the intercooler pipe (5/8") and it hardly worked.

I knew I had read that before...its only stickied at the top of the forum, thanks Curly. Yeah, the hole for the BOV is the exact same size as the flange and of the piston. I cant open it put the hose to my mouth and open it. So does that mean the spring is too stiff? It was free so thats why I am trying to get it to work. But if it would be easier just to buy a new one then thats what I will do. Here is a picture of it: https://www.miataturbo.net/attachmen...ine=1336080829

I have also tried changing the springs, there is an Ace right next door to my shop, and if I drop the spring rate then I can get it to open using a hose and pulling vacuum on it with my mouth. But when hooked up on the car, it is open all the time... I tried mixing and matching springs as well to see if I could find a combo that worked, but trying to use Ace as an automotive store looking for springs for a BOV doesnt really work so well. So would it be worth just getting an adjustable one?

When you say "open all the time" with the lighter spring, I'm assuming that means at idle? Mine did that before I knew how to adjust it properly, and it would snap shut with any throttle movement.

And does it work when it's like that? I'd get that one working even if it's leaking at idle before putting any money into another one. Try shimming the lighter spring with washers maybe?

Yeah, sorry, I meant at idle it is open all the time. I thought about shimming it but never got around to it. I also thought about trying to drill and tap the top and making it adjustable. I will try shimming it first though. Thanks for the tips, I will give that a try right now and report back.

So you say that with the other spring, the blowoff valve is open at idle?

What am I missing? I don't see the problem...?

Seems to me that the BOV should be free to open whenever there is a significant pressure drop across the throttle plate. At idle, this condition is satisified. I'm obviously missing the point - why is there still a problem?

You should adjust your BOV so it's just closed at idle, as far as I know.

Throw a filter on the BOV, and who cares if it's open at idle?

Just my 2c. Really, does it matter so long as the BOV operates correctly when not-at-idle and not running the AFM?

Yes! I used a different combo of springs, it stays closed at idle and works like a charm. No more compressor surge. For some reason I think I was worried about it leaking at idle, I was thinking afm for some reason even though I ditched that barn door. Thanks for all the help guys. Going to get my signal changing to post ic and pre tb... Other than smogged and getting tags this baby is ready for the road.

Thanks again