Has anybody adjusted the preload on their Blitz DD BOV so that the low moaning "phum" sound of compressor surge during low rpm shifting is eliminated? I've tried tight, loose and everywhere in between and can't get rid of it. It only happens when shifting at about 2000-2500 rpm. At higher rpm I get the normal psssshhhhhht sound.



ref: http://forums.maxima.org/showthread....highlight=phum

 

How loose have you had it?

 

Completely loose, i.e. no preload on the spring at all, so that some air is leaking at idle.

Weird, huh?

I've noticed that at low rpm shifts my boost gauge is showing a fairly slow drop of the needle from, say 10 in. Hg to 20 in. Hg. It is during that slow drop that the phum happens. It could be that the plunger is not getting enough vacuum assist during that time and pressure is allowed to build up in the intake until it surges (even with no preload on the plunger, though???). Shifts at higher rpm result in a much faster drop to full vacuum, which opens the plunger much faster before surge pressure is reached. Could this be what is happening?

 

I get a strange noise from the system if I ever drive around with the Overdrive disabled. I could never pinpoint it as it only occurs as I'm driving.
I've fiddled with the BOV as well but only to prevent that stalling condition whenever I decelerate quickly at a light.
Right now the adjustment screw is quite close to the bottom.

 

By close to the bottom I assume you mean most of the way in, i.e. near maximum preload? I tried that and it made it much, much worse, to where the phum noise would happen just from modulating the throttle a little bit when cruising at 2000-2500 rpm.

 

I don't think you can get rid of it... I've tried various settings on the BOV.

It really bugged me when I first had it... That's primarily the reason why I won't go to a HKS SSQ BOV... The sound would drive me nuts.

 

Are there BOVs that won't make that noise?

 

The greddy type s makes that noise as well, you just kinda get use to it over time.

 

my greddy type s did make that sound... I just loosened the bov up some and it went away....



P.S. I heard my greddy type s for the first time while my friend was driving and me out on the street listening... ITS FRIGGIN LOUD!!!.... its at least 2x as loud as inside the car... so beautiful

 

haha, yeah the noise the greddy makes is beautiful. I've been driving around in 15 degree weather with my windows down so i can hear the noise.

 

I thought i was the only one retarded enough to do that lol... Gotta love that whistle on the highway with the auto.... too sexy