Thread: Compressor Surge?

So here is a shot video of my car which i believe is creating compressor surge and the bov is doing nothing. I tried turning the little screw to softer but it didnt change the situation (tho i only turned it about a full turn or so becuz i didnt really have time to mess with it, had to be at work soon). I'm new to turbo and shit, but does this sound like compressor surge?

The stupid uploading site kinda stretched the picture out, but the sound is the more important thing here. First i put it near the filter to hear the surge then i put it by the BOV and like you barely hear anything if at all....
View The Video

That sounds exactly like compressor surge. Can you post a pic of the engine bay from on top the motor. It would help to see how your vacuum lines are run. Did you recently add turbo to your car?

Compressor surge happens at full throttle under load, and it sounds like the turbo "sneezes". What you have sounds like the compressor cavitating when the throttle plate is closed (the kids call this turbo flutter), which would be your BOV either hooked up to the wrong vacuum source, or adjusted too tight to open.

I bought it with the swap already done. Its running a blow through. BOV is vented to atmosphere (obviously). I can do you one better than a picture. Here is a video the seller took of the car (before I added the intake and a few other minor things that wouldn't have really effected anything). If you fast forward to the end (4:18) you can see the engine bay and hear the surge again (but without an intake).

https://www.youtube.com/watch?v=Go4--5gpq4o&feature=youtube_gdata_player

That's textbook compressor surge.

Right now I'm shifting early and releasing acceleration slow to help combat/prevent it till I can figure out how to fix it as this is my daily driver. At least it's "textbook" and not something crazy going on. Think maybe the bov is to tight? I turned the nut a bit like I said but couldn't do much cuz I needed to goto work and I couldn't afford to not have the car running. It's a type rs not sure on authenticity tho since I didn't install it.

After looking at the bay and vacuum lines do they look right? Also bov is installed behind from bumper, beside driver fog light, vacuum line passenger side and discharge facing driver side. Is that right?
If all the hookups and installs look right, maybe I'll just turn the bov until a hear air escaping on idle then give it about a full turn or so too tighten it. Sounds about right? Sorry, like I said, trying to understand

that is surge and you should use a vac pump to see when your bov is opening. It may be adjusted wrong or it could just be a defective unit. The bov should have a strong vac source. the brake booster line is good or you can always tap the manifold for another source.

Any BOV with an adjustment screw/knob belongs in the trash IMO. I've never seen one work properly nor have I ever seen one set properly.

I've never seen a non-adjustable BOV malfunction.


Check to make sure your BOV is getting a proper vacuum signal. If it is, I'm pretty sure it's borked. And I'm not surprised.


I don't know about your setup, but on a properly setup T25 and T28 build the BOV will be venting at idle. Making it closed at idle is not right. If you have to do that because you're venting to atmosphere, I suggest you seriously reconsider recirculating the BOV (and be mindful of where the MAF is installed).

I'll have to double check the source and line. Where can I get a vac pump? Can I use a air compressor? I assume I'd just hook it up to the vac line of the Bov and see if and when it's opening?....you meant "break" booster line? I thought it was going into the manifold but I'll double check with pictures soon as I go on a break here at work.

Local auto-parts store.

Does your air compressor create a vacuum? Likely not.

No he meant "brake".