Yes I did a search and found several things about boost flutter but nothing that was quite what I am experiencing. In an effort to resolve some boost leaks I recently replaced my throttle body seals and checked all the IC connections etc. My car is totally stock except for a BR air filter. I wanted to upgrade my plastic bodied stock BOV to a metal bodied one from an MR and just got one from a fellow EvoM member and put it in tonight.

Here's my question. As I decelerate from a low boost (just cruising around normal driving and get boost up to 10-+ psi and slowly let of the throttle) i get a slight flutter from the BOV. I doesn't flutter as it builds boost and if I get completely off the gas quickly (from any amount of boost) the BOV vents completely as it should. It seems to only be when I'm at low to moderate boost pressure and lightly get off the gas that I'll get a little flutter.

Is this normal? Never had anything like this with my stock plastic BOV. Didn't expect it with a stock metal BOV.

 

yea its pretty normal....atleast if im understanding you correctlly.... when you come off the gas...it kinda flaps a couple times and then closes.?

 

normal

 

I'm only asking because with my stock plastic BOV it was one big "whoosh" as the BOV would vent when you let off the gas. This new metal one is the same unless I'm slowly coming off the throttle and then its 4-5 little "squirrel chirps" as I like to call them.

Still normal? Thanks for the repsonses.

 

its compressor surge.....and its normal under low boost/load conditions. When you have a bov that can hold more boost you will sacrifice it not being able to open as easily at part throttle stuff - so you get a flutter sound which is compressor surge.

your plastic one didn't do it because it was weak sauce.........

 

I get this too with the stock MR DV and a 30R. Little annoying and can be jerky cruising on the highway @ 75 when the turbo is just about starting to make boost. I was thinking of trying a synapse bov as they're supposed to respond quickly to changes...

 

Makes sense. Thanks. So there's no issue with it causing any negative affects other than it being a little annoying right?

I don't notice any problems with how the car behaves, it just the flutter sound.

 

Good thing I saw this thread I had been experiencing the exact same thing and was starting to wonder if it was normal or not. I also just upgraded from the plastic BOV to the metal one.

 

Is the synapse bov a known fix for this, or is it just sales hype?

 

It can cause damage. there are a couple threads regarding it!

 

that kind of surge would take a very long time to hurt a turbo if ever - the effect is minimal. Its low boost, low rpm surge from the pressure not being strong enough to open the dv so it diverts back through the turbo (basically).

The kind of surging that is bad and could hurt a turbo can get pretty violent and this is not what he is experiencing.

 

normal observation to make, nothing dangerous happening.

 

This happened to me also, turns out there was a small piece of plastic from tapping in the boost gauge hose upstream from the vacuum hose coming off the bov, must have made just enough blockage to make the valve flutter under low boost conditions. I'd check that vacuum hose and connections to the bov, mine runs great now.