N75 valve replaced, now I have 5 psi more boost?
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AudiWorld Senior Member
Joined: Sep 2003
Posts: 894
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From: Roy, WA
N75 valve replaced, now I have 5 psi more boost?
I was only making about 11~12psi boost reading wonderful Modschack boost gauge. Car wasn't throwing any codes but it used to boost 12~14psi. I replace my N75 "C" valve with a "H" valve from my old AAN Turbo 5 and now I get build to 18psi with it settling at about 17~17.5 psi. I wonder if the old valve was just bad? Do you guys think my car is chipped? Can just the "H" valve do this much on its own? If they are stock chips will my fuel curves be way off with this much boost? The car builds boost great now, no spikes, just smooth.
Thread Starter
AudiWorld Senior Member
Joined: Sep 2003
Posts: 894
Likes: 77
From: Roy, WA
I do have Vagcom so I will check, does anyone know of anyway to check to see if my car has been chipped/flashed? Anyone else running the "H" valve? I don't know of any Vag way to check on the software.
AudiWorld Member
Joined: Sep 2005
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not chipped...that's what is designed to do
the H valve is made to increase the boost a little by lowering the duty cycle on the valve. There fore boost can shoot up and stay a little higher before it will bring it back in check. I think the duty cycle can be equated to the amount of time the valve is checking itself to when its' not. So if you DC is high, the valve is always monitoring and the boost will rise a lot slower and will be very exact. If you lower the DC as they did with the HValve, it doesn't look as much and it can shoot up to higher boost before it says, hey, check that. They it also brings things back down slower because it's not watching it as much...thus a higher boost across the rpm. That Hvalve is no way a direct oem replacemnt...
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