[Biturbos4] Alternative Boost Gauge Tap-in Location

j y jimnetpa at yahoo.com
Mon Jul 11 13:38:25 EDT 2005

Well...it's pick your poison. All I'm saying is that I've tapped into the N249 w/o any problems..but I've also DISCONNECTED the N249 (to get direct manifold pressure to the DVs)w/o any problems either. Like I said...the N249 is there to help the ECU regulate the DVs..if there is a major boost leak. The N249 also supplies vacuum to the secondary vacuum canister..if I remember correctly. I RECONNECTED the N249 because I'm already running high boost (17-18 psi) and I've adjusted the fueling via Lemmiwinks...like many guys in the B5 S4 forum on AudiWorld. So, I decided that reconnecting the N249 to maintain the stock safety mechanisms that Audi established was a good bet...since I am living on the edge already.

Quincy Chiang <b5quattro at shaw.ca> wrote:
So you're saying this isn't the ideal location either due to the fail-safe mechanism this line is tied into. Are you planning on finding a better location? I wonder if a leak does occur to the boost gauge vaccum line, which tap in locatoin would be worse, the one I have right now (to fuel pressure regulator) or yours (to N249).


----- Original Message -----
From: j y 
Date: Sunday, July 10, 2005 1:26 am
Subject: Re: [Biturbos4] Alternative Boost Gauge Tap-in Location

> I've tapped into manifold pressure before & after the N249 (DV 
> control valve). It requires re-plumbing the existing hoses - 
> fairly time consuming process. Because the hoses are not long in 
> length and need to be spliced and replaced with new vacuum line 
> and a tee (to hook up to your AWE gauge). It worked for me when I 
> disconnected the N249 to get better DV response at part throttle. 
> Only problem - the N249 is on of the ECU's fail-safe mechanisms to 
> reduce turbo failure (allows the ECU to manipulate the DVs in the 
> case of a major boost leak) - just like "limp mode". Good luck.
> Quincy Chiang wrote:
> Hi everyone,
> I need to replace the vacuum line on my AWE boost gauge, and I 
> want to change the tap in location from the fuel pressure 
> regulator to the intake manifold pressure. This is because a leak 
> at the existing tap in point can cause the car to run lean, not a 
> good thing at all. So my question is where is the intake manifold 
> pressure line? Thanks for any help!!
> Quincy
> '01.5 S4
> '90 CoupeQ
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