Ive been driving my car around and noticed the diverter is fluttering. It does it at about 2 or 3psi and up, its not the turkey gobble flutter though its like the valve is bouncing between open and closed(maybe not fully closed) like a pshh psshh pshhh. I run the forge piston style diverter with the lightest spring. I regreased the whole valve to make sure its not old grease making it stick. Would I see a spike in backpressure if it was compressor surge? I monitor my back pressure and it doesnt spike up at all.

Just to clarify this same valve worked fine on me until this year where I switched to a large front mount, 3" IC pipes and SFR stage 1 headers.

 

check the vacuum/boost source connection

 

I checked the line its fine even replaced it with a new silicone vacuum line. I did put a gauge on the line to the diverter and its about 15psi at idle boucing a little back and forth like less than a psi. When the engine is revved up and throttle let off it goes to 21-22psi of vacuum. So im not sure why its doing that, would a light spring cause this maybe? I have a medium, heavy and some shims to bump up the spring rate in the diverter?

 

The heavy springs are not going to hurt anything

 

ok sounds good I will try shimming this spring then a heavier one if that doesnt help. Also I said 15psi vacuum at idle I meant 15inhg when cold and 17-18 when hot and when I let off its move like 25-27inhg vacuum under load

 

Interesting. I think this is the issue with mine. Same pshhh psssh noise at low boost and I didn't think anything of it because I changed from AFM to MAF at the same time and didn't know how it should sound.

Tim- you're running fairly high boost?

Anyone- the Forge spring kit fits the Evolution Motorsports valve, right?

 

I have it set for 15psi now but I do flow alot of air and im thinking because I have a large turbo and large IC pipes and IC that im flowing alot more air then with the stock IC and pipes.

 

Well I tried every spring that I have with my forge kit no good, I even tried both orientations still flutter is present. I put pressure on the side port of the forge and it turns out it leaks so im going to try finding a cheap bov local and see if that one flutters also.

 

try that cheap ebay unit 50.00

I used it for quite some time at even over 30 psi w/o trouble. I had the heavy spring and washers installed

I'll find the link. I couple of others have used it with good results

 

link
http://cgi.ebay.com/ebaymotors/Bosch...spagenameZWDVW