The BOV that came with my Inlinepro kit recently failed. I bought a Greddy RZ to replace it since it was the same flange. But I got compressor surge from it I could not get rid of. At idle I could see it actuate just how it should. However if I went over 5 psi of boost I got surge. I tried the single spring mod, I tried cutting the spring and I even ran it with the spring completely removed. None of that eliminated the surging.

I assumed the problem was the Greddy unit and purchased a Synapse to replace it. But the exact same problems happened.
I also changed my charge pipes so the BOV is on the cold side right by the throttle body after reading that that could be the problem, but that didn’t help either. I’ve tried multiple vacuum sources as well. I used the one at the back of the throttle body, I tapped into the FPR line and I even (temporarily) tried the line for the MAP sensor. I even tried using different types and sizes of vacuum line. Nothing seemed to work.

I hear the fluttering sound whenever I let off the throttle or shift. It only happens above 4-5 psi. It happens at both partial and full throttle; although it is louder and more distinct at partial throttle. To get a baseline I disconnected the BOV so it stayed closed and I heard the exact same sound.

Sorry to be long winded but I didn’t want to leave out a detail that might be important. Does anyone have an idea what could be causing this? I’m stumped and getting really frustrated.

 

Sorry to hear this is happening... I'm not sure I can help, but I'll ask some questions to give your thread a free bump.

What turbo? Internal or external wastegate? (I thought the fluttering sound on my greddy kit was my internal wastegate... Guess I'm wrong.)

Is the Synapse adjustable, and have you adjusted it? Have you called the vendor or spoken to your tuner about this noise, and/or about adjusting the BOVs?

What kind of BOV came with the inline kit? Have you asked them for suggestions?

Do you have pics of how the BOV is currently installed? Sometimes people notice stuff in the pics that nobody thought to ask about.

Do you have video or audio so we can hear it happening?

Sorry for all the questions - you've probably thought through all of this already. I'm just trying to stimulate discussion so people can help.

 

We just had a thread on the synapse BOV, I stated in it that I could not get it to work on my inlinepro kit. I eventually returned it. The stock IP bov is the best one for the kit, get a replacement.

 

I read that thread. I thought the issue was the hotside vs coldside placement? I'd really rather not get another of Inlinepro's BOVs considering how quickly the first one died on me. And I would really like to understand why no other BOV will work with their kit.

 

Mine has been working for a few years, must have been a fluke

 

I REALLY like the thier BOV, my first impressions was that the valve would be a disapointed but after using it I will never go back. The vavle is very simple what failed? I am sure if you call IP they can get you parts cheap.

 

where do you have your vacuum line to the bov connected on the intake mani?

and are you sure its the bov creating surge and not part of the turbo thats failing?

 

Doesn't surge usually happen in the opposite way you are describing? most people that see surge see it at lower rpms where the bov spring might be too still but at higher boost the bov is able to vent properly. your situation seems to be backwards.

 

Same exact thing happened to me when I used the synapse bov on my IP kit. Surge at ~5psi+, nothing at partial throttle.

 

I had the Synapse unit connected to the vacuum port at the rear of the intake manifold:

(ignore the line running along the firewall, that's for the water/meth kit with is currently out of the car)

I don't think it's the turbo because if I disconnect the BOV so it stays closed it makes the same sound as when the valve opens under boost.

And I'm don't think IP sent me their BOV when I bought the kit. What they sent me looks nothing like what is on their website.


What failed was the diaphragm. The rubber coating on it had been stripped off the "bottom" side and the mesh underneath had several tears and holes. I noticed though that the internals of that one and the Greddy were very similar and the diaphragms where identical. So I switched them and reinstalled the IP unit. I'll see what happens.