Questions regarding compressor surge

A

AZMS3

Member
Yesterday I installed a Greddy Type S bov (not ebay knock off) that was used. It is supposely setup in rec. mode and was setup already for the Speed3. It is holding boost great and no issues at idle or stumbling. The car runs great. The problem is that it doesn't make the whoosh sound, instead it flutters. Im not sure if this is normal, but I listened to other sound clips and they did not sound like mine. What can I monitor to look for signs of compressor surge, not sure what to look for with monitoring. Does anyone have any idea what is wrong or if this is normal?
Thanks
 
usually when it flutters, the bov or bpv adjustment is too tight. not familiar w/ greddy bov but it usually is the culprit (fluttering). what psi you're spiking @?
 
sounds like compressor surge(valve is opening under boost so the air is hitting the turbine. you need to adjust it. i found like 100 ways but the way i got from greddy is...

loosen the nut and adjustment screw, then tighten the screw until valve stays closed at idle.

what i did was put it on the car backwards so i could see the piston. block off the recirc. hook up vac. start car(get it to normal operating temp). and with screw to loose (or loosen till you see the piston isnt shut) start tightening till the valve stays closed. then give another quarter- half a turn (to accomodate enviromental changes) and your done. reinstall right hook up the recirc blah..

drive it and you shouldnt get surge, if you do its probably too tight but shouldnt.

now from reading i came to understand that the adjustment isnt for sound etc. its only job is to keep the valve shut at idle. under boost the vac referance line is supplying the same pressure as in the pipe so that holds the valve shut. it isnt till you release the gas and the pressures are different that it opens. wow that was long take it as you want it.
 
I have an authentic type s as well. I would loosen it for starters... Mine does a slight bit of backspin (but not really any surge) at boost levels around 5psi or less into the vac range. When I get on it and hit peak boost or much above 5psi, the pressure will kick open the valve during shifts and it will whistle like it should.
 
rmgedon69 said:
usually when it flutters, the bov or bpv adjustment is too tight. not familiar w/ greddy bov but it usually is the culprit (fluttering). what psi you're spiking @?
Click to expand...

It will spike to 19 psi and hold around 15-16 psi. With the bov it pulls great, but then when it releases boost is when it flutters. Im getting short FT at 14 at WOT. I think this is too high, but not sure.
 
Well... it is most certainly tight enough to hold what you're spiking... your problem is that it is too stiff and just staying closed the whole time, hence why you're getting compressor surge.
 
Saskatchewan17 said:
I have an authentic type s as well. I would loosen it for starters... Mine does a slight bit of backspin (but not really any surge) at boost levels around 5psi or less into the vac range. When I get on it and hit peak boost or much above 5psi, the pressure will kick open the valve during shifts and it will whistle like it should.
Click to expand...

How much do you recommend turning to loosen it (first time using aftermarket bov) . The bov holds boost great, but I only get the flutter sound when releasing the boost. Also do you think that the bov could be causing high FTs. What should be normal FTs, A/f, while WOT or under normal load, anyone know. Thanks
 
Saskatchewan17 said:
What are your mods and are you on the stock tune or not (standback, ap).
Click to expand...

I have cobb intake and greddy bov. i have the ap but not the license yet.
I went and loosened it 4 turns and it is still fluttering. How do you find the best spot. My bov does not have the sticker on top of it, so I do not have a
reference point to go off of. First time setting up a bov and getting super frustrated. Help me out, thanks
 
Last edited:
It doesn't have the sticker? Does it have the greddy "plaque" on the side? Are you sure it's a real type s? Also, is the adjustment screw tightening/loosening easily? Mine had stripped threads when I bought it so I had to retap the damn thing...

What I would do is tighten the damn thing down as far as it can go, then loosen it back out. The spring might be stuck on a hard setting right now and by tightening it down all the way you will seat the spring back on the adjustment screw. Then loosen it back up to a pretty loose spot to see if the spring loosened enough. After that, just ride around and tighten it periodically to get it to a setting where you will hold full boost but not get compressor surge.
If THAT doesn't work... take the valve off the car, then take the purple cap off and see if you can see anything wrong with the valve internally. Make sure all the bolts on the cap are tightened down and the vaccum nipple screw is in correctly. Also, check the vac line running from the BPV to the intake manifold (I believe?).
 
And be sure that it is bolted down on the IC cold pipe correctly; nice and tight. AND that the valve is on the adapter correctly and tightly... preferably with a gasket... if you can see on mine:

20091021_0252.jpg


You can see the adjustment diagram here as well.
 
Oh, if OP have the same bov than yours Saskatchewan17 and you don't get flutter noise then yeah OP have a problem. Inspect the bov throughly.
 
So if you're on the stock tune and only have an intake your A/F ratios should be around the mid-high 10s to low 11s. Mine are like 10.8-10.9 at WOT in 3rd.
 
Saskatchewan17 said:
And be sure that it is bolted down on the IC cold pipe correctly; nice and tight. AND that the valve is on the adapter correctly and tightly... preferably with a gasket... if you can see on mine:

20091021_0252.jpg


You can see the adjustment diagram here as well.
Click to expand...

I put everything on really tight. I even put a gasket on with it. I think that the bov is holding closed, which is causing the flutter. Im trying to open it up by turning it towards the soft side but have no idea how many turns. Thanks for the help. Regarding my A/F they are right around what you mentioned.
 
Saskatchewan17 said:
It doesn't have the sticker? Does it have the greddy "plaque" on the side? Are you sure it's a real type s? Also, is the adjustment screw tightening/loosening easily? Mine had stripped threads when I bought it so I had to retap the damn thing...

What I would do is tighten the damn thing down as far as it can go, then loosen it back out. The spring might be stuck on a hard setting right now and by tightening it down all the way you will seat the spring back on the adjustment screw. Then loosen it back up to a pretty loose spot to see if the spring loosened enough. After that, just ride around and tighten it periodically to get it to a setting where you will hold full boost but not get compressor surge.
If THAT doesn't work... take the valve off the car, then take the purple cap off and see if you can see anything wrong with the valve internally. Make sure all the bolts on the cap are tightened down and the vaccum nipple screw is in correctly. Also, check the vac line running from the BPV to the intake manifold (I believe?).
Click to expand...

My bov is the Chrome look on top. It does have the Greddy sign on both sides of it. I will for sure tonight try and set it as tight as it goes and then work from there loosening it. I did notice mine is hard to tighted at certain points. Also I noticed on your pic of your bov that your screw sticks out way more than mine where you would adjust it. Do I need to take the nut off before tightening or loosening it up. I have been just loosening the nut and then turning it with an allen wrench. Thanks
 
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