How tight or how soft should the spring be? I've done the single spring mod & it idles great.

But if I'm in 5th gear in low RPMs, accelerating slowly, and then slowly let off, there's a slight flutter that comes from the BOV. Is this normal? What or how should the BOV sound when it's adjusted properly?

I've got an MBC, AEM Short Ram Intake, the BOV is recirculated, HKS 272/272 cams and the MBC is set at around 22.5psi.

Any suggestions or ideas? I'm lost

 

Come on, no one?

 

mine flutters and yes I too have done the spring mod. In fact, under 22 pounds of boost and letting go of the throttle the whole car shakes, don't know if that's normal.

 

Hi. Mine does the same thing. I sort of changed my driving habits with it so I dont get the flutter when I lift slowly. I have the single softer spring in it and it holds boost just fine. With both springs in, it fluttered all the time.

I have it set a little more on the firm side with the soft single spring.

 

What do you mean by flutter... I have he same set-up and can hear the valve letting off (whistle) with light throttle lifts. It should! It needs to dump the excess air out of the system. If it is too tight when you lift it will over lean your A/F mix. I have the adjuster screw about 4 turns in from the "friction point", when the screw hits the locate plate inside. I also run with the primary vac line and the secondary capped off. I put the upper IC tubing to the bottom of the BOV and the Air box side to the side discarge port. This whisles while it leaks down but is more responsive than the other way around. Oh, and yes you can run it either way. I just don't like it that the vac would have to pull the plunger against the puch of the boost. This way the boost is puching and the vac pulling for a faster "lift" of the plunger...

Hope this helps.

 

WOW i was just going to post about this also, Ive had my car for about 4 months and about a month ago I installed a greddy type s. It works goods but i get that flutter (while WOT gear shifts and letting off the gas) also and its not very loud becuase i still have it recirculating. Is that flutter normal or can it be adjusted to get rid of? Ive also noticed that my car is running a little rougher lately but its reaching 16k miles so i think im going to have them do a tuneup. Im trying to keep a good dialog with the dealer so they wont challege any warrenty claims in the future.

 

You do NOT want to hear that fluttering noise. That is surge, not good. Loosen up the spring. You want it tight enough to hold boost, but loose enough not to have that fluttering noise.

 

My Mods that would possibly affect the Vacum/BOV are a Samco intake box-turbo replacement hose & a Helix DP, Works RTP & JIC catback with no silencer.

im running the Type-S with both springs & i have the Adj-screw backed all the way out but still in far enough to locate the spring perch. although im also using the anti surge port, wich i currently have Tee'd into the compressor housing outlet that feeds the Boost Controller input (to be moved closer to the throttle body in the near future)


with this setup i have no flutter, it holds boost like a champ (light throttle tip in improved greatly) & where the valve stuttered & surged before, it now has a clean Whoosh/whistle as it releases the pressure

 

Can the single spring mod hold 24psi properly? What's the limit of the single spring?

 

Is that whistle a loud chirp? Cause i too have an intake and i am about to get a greddy type-s. Is it noticable with the intake?

 

I spent all day driving around adjusting the damn thing today, and no matter what I do I still get flutter in 5th gear, it's so annoying.

 

i did some experimentation with the diffrent springs/screw adjustments & compared them to the my cars vacum reading & the OEM valve using my vacum tester. in my opinion one spring is too soft & the only reason i can see running it this way on an EVO is if your cammed & are unable to pull enough vacum to open the valve


FYI anymore than 2-3 turns on the Adj screw & you will be limiting the pistons travel. so it is advisable to get it as close as possible by using the springs & then using the screw for fine tuning


6one9EVO, i only have a Samco Silicone hose to replace the stock accordian tube, i am still using the OEM airbox. the sound is very faint & high pitched, you probably couldnt hear it more than 20' away & it sounds more like a high pitched whistle than a chirp. though from my past expieriences id say with an open element intake you will only be marginally quiter than a VTA BOV