BOV flutter or surge?
 

Ok, I thought I'd post this here to get some more opinions. Running anything above 5psi and letting off the throttle results in 5-8 "flutters" The more boost, the louder they are.

I am running a supra recirculating BOV and I tried a Bosch one as well with the same results.

I am recirculating into the tube between the air filter and compressor inlet. I have a megasquirt so no AFM. When I had my VAF in there it didn't make the sound, it only does it now once the VAF was removed for the megasquirt install.

The BOV hose is around 3/4 inch inner diameter.

My question is - do stock recirculating BOVs make a fluttering noise? Both BOVs I tried were stock recirculating ones.

Thanks for any input.

I should add, at low boost pressures, I hear a normal BOV sound ... at 2-3psi for example. The fluttering happens only at higher boost levels.

Sounds like it was probably always making the noise, you just didn't hear it when the MAF was in place...or...it just started making the noise because it's on its way out.

swap out the bov with another and see if the sound changes- if it does, it's the bov

Tried two BOVs and they make the same noise.

I will try attaching the BOV to a different vacuum port.

The miata doesn't have lots of vac nipples - I found the same thing, until I removed the brass shim/disc? spring seat? from inside the BOV, and tee'd it into it's own vacuum nipple.

I only get a little bit of flutter on really light boost, but no flutter on higher boost - just the pcsssht sound :D