I just installed a GFB MBC and noticed that it seems quite a bit noisier than my old MBC. I checked the hose fittings and everything seems to be fine, and I confirmed the MBC as the source of the sound by covering it with my hand. When I cover the MBC the noise goes away, so I don't think it's the hoses. Is this normal? It seems like a low level hissing noise almost like an air leak, and it goes away (of course) when I shut down the engine.
Thanks,

-n.

 

most likely it's a vacumn leak, check the input/output on your MBC... Most cases are due to incorrect install. Hope it fixes your problem

 

I also installed a GFB MBC and it also makes the hissing noise. I tried 2 of them since my brother also has an EVO without an MBC. They both make the same noise. It's the MBC not the lines, I replaced my lines too. The problem I was told it may have is you maybe running lean. So get an A/F gauge and find out. I put a new MBC from turbonetics and no air leaks, the problem I have with it is that even with it turned off the boost goes over 1.6 bar. i'm trying to find the problem. I already changed the hoses again, and no fix in sight...

 

NO, they told me that it's a bleed type MBC so the hiss is normal. This is from the GFB folks in Australia. Most MBC's are ball and spring so they don't bleed air like the GFB.

 

Either way, I put my GFB back in my car, and still works like a charm. Hissing and all, yeah, and I read the bleed type MBC thing before, I just couldn't remember where. Anyhow, how much boost you pusshing with the GBF MBC? I had mine stick at 1.4 bar/20 psi.

 

Yeah, that's exactly what I'm doing as well... seems good so far..

 

I took a picture while I was driving it a few weeks ago(of the boost Gauge) at 1.4 bar, and I took a picture of me going a bit over 150mph. Too bad I don't think I should ever do that again. Too dangerous. Driving with one hand and taking a picture with the other. I'll NEVER do that again.

 

Hahah thats gotta be insane. Ive only been up to 143 with both hands on the wheel !!!!