I know surge, mine's not surging. Trust me on that. The video doesn't pic it up well. My bov will open before the boost guage even gets to the positive side. You're hearing me pedal the car at high rpms which on a small td05 18g at 4000+ rpm results in instantaneous boost changes. No I haven't driven with the filter off, but having reved the engine up with it off inside the garage I can guarantee you that mine doesn't surge. I run a completely dedicated line to my bov only which means it has much better response than a bov that's tee'd into a manual boost controller line.

At 3500rpm plus when pedaling the throttle you can actually hear the bov open and close extremely fast giving a "cha-cha-cha" sound as the angle of the throttle plate constantly changes and the bov responds to those minute changes in vacuum pressure. Were this to happen on a car without a gm maf and a properly vented HKS your car would stumble during this minute changes as it ran rich due to the venting of pre-metered air being dumped.

I will try to get this video made in the next couple of days. I have my bov dedicated also. First open nipple to the right of the pcv valve. My mbc is run off of a nipple from the lower ic pipe to wg. If i rev mine with no boost i have a very slight chaa chaa without the filter. If u would try just going around the block once without the filter. Im not doubting you at all. I am far less knowledgable as u are, but my car sounds the same as yours under boost and letting. I can pedal mine and I have no stumbling. I can hear the bov letting off, but still have that (other) sound.

As for modding the bov, i tried the heavier spring and it is too heavy, i have to find a lighter duty one. SO then i tried a 7/16 washer behind the one nut against the diaphram, and two washers in the spring cup on the other end. Bov opens all the way still and it holds till about 14 psi and then just blows wide open. So i still need to find another spring.

Here are the videos, i had to use my digital camera. Sound is ok and gets the job done. The first one will be with the filter and the second is without the filter.
http://s80.photobucket.com/albums/j190/yellow90tsi/?action=view&current=DSCF0784.flv
http://s80.photobucket.com/albums/j190/yellow90tsi/?action=view&current=DSCF0785.flv

Mavisky or matt or anyone, any ideas?

Just curious, how much boost are you running there?

That sounds alot like my bov at very low pressures where the smaller chamber does flutter a little bit.

Remember that at low pressures some surging isn't terrible. Many cars such as Buick Grand Nationals and small psi turbo kits for other cars don't come with a BOV due to the low amounts of boost they run. If you're surging at 20psi then you've got problems.

Here's a more recent video of mine releasing about 15psi in first and second

http://www.youtube.com/watch?v=tu8mE2lvzRs

Here's me short shifting first at about 2 psi and then crossing the line at full boost - and my buddy chris on the Mike making fun of the HKS

http://www.youtube.com/watch?v=HBnRP-wTy6o

In both of those videos im running 15 pounds and short shifting kind of. Last night i did a decent run and nothing but bov, so im thinking the turbo needs some more boost. But would u agree thats surge? And u think that it is ok?

Yellow90tsi, that first sound of your vídeo is exactly what mine did before modding it.
It's the bov not fully openning, it just opens and closes fast.
You need a softer spring if you want to get rid of that or do the mod i did. But you can't vent to the atmosphere anymore with tat mod.

I compared a HKS of mi friend's Nissan S13 and my cheap copy one and his spring was softer than mine. That's why his valve doesn't flutter and opens all tha way and quickly.

mavisky said:

http://www.youtube.com/watch?v=tu8mE2lvzRs

Click to expand...

That's the signature hks bov sound.

Well how come there is a different sound with or without the filter then. I vent to atmosphere. So why in gods name would the sound be different with or without. Now today what i did was in the 1/8 inch hole i drilled in between number 1 chamber and the number two chamber i put a 1/8th inch roll pin and it closed up my hole. I didnt get to drive it yet but at least the hole is the same diameter as the vacum hole on the last chamber. I will let u guys know tomm. how that works out.

I have recently went gm maf and bought a nock off hks bov i had to take the thing apart because it wouldnt hold vac. so i put some oil on the diaphram and it started to open still leaked down with a vac pump so i put the thing on it worked and sound great but i could here it comresser surging so in the meantime i had ordered the real deal (hks ssqv) it is really compresser surging i dont know about you but i dont want my new bb 50 trim busted in half these valves in my opinion are a waste of money and im really upset 260.00 wasted between the 2. Also if you spend 180.00 on something the sun of a bi*** better work out of the box!!!!

that other sound could be an externall WG

Yes i know this thread is over three years old, however ive been having the same problem with my hks and it is the second one ive owned. For the record they are both genuine hks ssqv, and at first the problem didnt exist, the first hks i had was on my honda and it used to make the cracking whoosh noise at wot and low throttle it would chatter a bit, after a while all it would do was the chattering surging noise. Now i have a talon so i bought a brand new hks ssqv and when i first put it on it was recirc and was ok, then i got a gm maf and put the fin back in and it was F**kin loud and awesome, put the recirc fitting back on to see how that sounded and drove it like that for months because i lost the fin(long story)SOO i bought a new fin for it and put it in today and guess what? it doesnt sound any different than the recirc fitting, or with no fin, no high pitched scream at all just a surging chattering noise which i had become accustomed to and thought it just sounded like that with the recirc fitting on. is going on here? two brand new bovs doing the same thing?
Idk what to do , nothing has changed as far as boost levels, vacuum source ive tried switching to dedicated and it doesnt help, the only thing i can think of is either the diaphragm is torn inside of the bov or the o-ring under it is messed up from moving it around on the flange.... ANY ideas guys? Also this bov is under a year old

Try to disassemble the rear side (where there's a lot of small bolts). And clean the inside of the big nut with WD-40 through the little holes or disassemble the nut and spray it from the thread side.
Then apply some grease to the shaft too.

It might not be Your roblem but that's what fixed mine when I got one used from another guy. In fact mine wasn't even blowing off properly.

If i get some time today im gonna take it apart and have a look, there is no adjustment screw on this bov however. Im guessing for some reason the secondary valve isnt opening and all of the air is going through the first smaller part, making it surge and taking alot longer to release the air, maybe i tightened the cover too much wheen i put the fin back into it?

when You remove the rear cover and the spring, check if the shaft and big balve gets stuck or something as You will be able to move them freely now.

Its just so frustrating and crazy that we would have to modify a 200 dollar brand name blowoff valve to work right, hks should be aware of this problem and have remedied it by now

Well it snowed quite a bit today so idk if ill be able to pull the back off like i planned, are all the parts going to fall out when i open it? I was going to leave it in the engine bay and just take the back off but i dont wanna lose any parts

that's an amazing s14 haha

Small update: i twisted the bov at a different angle and maybe it sealed a bit better to the flange, but now at wot when i let off and switch gears i can hear the high pitch whistle for a short second, but still not like it was. Im wondering if its just me now . Also i removed my sound deadening from the firewall and have some open holes in the firewall so i hear alot more engine noise im thinking this may be cancelling out the whistle so I cant hear it