Thread: Quick compressor surge question

Ok, so i finally got my car runnning with my bb t25 setup. Runs great, idles great, and is a lot of fun. Only problem to speak of is that I have some compressor surge going on. I have a knockoff greddy type s which is brand new. I tried backing the screw on the bov out some, but it still does it. It may have more to go, but it feels like its pretty far out. The vacuum signal is t'ed into the fpr vacuum line. Is this signal too weak? If so, where do you suggest getting vacuum from? My boost gauge only shows boost, no vacuum so I really can't see what the bov is seeing. THanks

Greedy and Greedy like BOV's have two springs, unless you have vacuum sources going to both nipples, you will need to remove one spring, the small one probably.

Thanks that sounds like a good idea. That'll give me something to do on lunch tomorrow if its not raining.

And you need to adjust it with a vacuum pump (you can rent one from autozone or whatever):

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You have your boost gauge hooked up wrong. It needs to get signal from manifold preassure. Do that and you'll read vacuum too.

And to comment on what Vadim said, it is my understanding that the second nipple on the BOV is for assistance in keeping the valve shut under high boost levels. If you're running low boost, which you likely are, just do as Vadim said and remove one of the springs. Try that and let us know.

so your telling me the line from the manifold to the fpr doesnt get signal from the manifold pressure?

My boost guage only has numbers for boost. It's not a boost/vacuum guage, only boost. I guess I wasn't really clear.

I took the smaller of the springs out of the bov. You can still here surge, but i think its letting the pressure out because I hadn't recirculated the bov yet. It ran normal. After I took the spring out, it was running real rich (no wideband to tell me, but it was backfiring a lot) Once I recirculated the bov, the backfiring stopped, so I'm guessing that it is at least letting air out now.

... I have no comment for you.



So I assume that you're running a draw through setup. On a draw through setup you have to run a recirculated BOV or you'll run super rich between gears and at idle.

I just assumed you had a boost/vacuum gauge with which you wouldn't get a vacuum reading unless it was tapped into a manifold preassure source.

If you're still having surge issues try loosening the BOV a little more. If that doesn't help you might want to pull the BOV apart and try cleaning it. That's the problem I have with my Blitz, it was super dirty. I cleaned it up and it worked a lot better bu I didn't clean it well enough so I still have a bit of surgeing going on due to it sticking when it opens.

Just looked through that "how to" write up about adjusting the bov. Def doing that tomorrow.

Yup, good idea to use one of those. If you really don't have the time/money and not running too much boost, you can get away by living it mostly out.



I wonder if the FPR line is too small in ID, thus not sucking the BOV open as quickly?

You can use the second nipple, it basically prepares the BOV to be opened. Either way mine broke off, knock off quality at that, and thus I had no other choice but to just remove a spring.