Maybe I'm thinking about this incorrectly but if the air recirculates it's not going into the system a "second" time. It's metered air that is still contained in the system. As you said, it recirculates after the MAF. This will insure that more air is not pulled in. If you vent the air to the atmosphere you're going to create a vacuum and suck more air past the MAF that isn't being used by the car at all. This in theory is what all the "rich" arguments are about. The system wouldn't run "lean" with recirculated air because the ECU knows exactly how much air has passed by the MAF and should be able to accurately provide the right fuel mixture. However, if you vent and pull more air in. The ECU will think there is an excess of air in the system that actually isn't there at all. It's exactly the same reason the car will run rough at idle if you use a BOV that doesn't have enough spring tension. It will leak into the atmosphere and create a rich condition that confuses the ECU and makes your vehicle idle rough..

I have tried several BOVs with varing spring tensions myself without great results. I might even experiment with the turboXS ones because that's the only brand I haven't tried at this point. One thing I worried a lot about was the additional pressure put on the system. As you mentioned yourself you had hoses blowing off. Maybe this is due to the fact that the divert location does not provide enough flow? I always thought it was because you had to make the spring tension so tight that it needed too much pressure to open. That's another thing that always bothered me. You're changing the design all together. The stock system only uses vacuum to open the valves. Most BOV only valves require boost pressure and vacuum to create a differential condition...

Sorry that was long winded and you'll probably not get a chance to read it. Good luck and MOSPORT and I ALWAYS enjoy reading your posts. I don't mean to sound like I question your knowledge I'm just trying to understand it a little more myself.

regards...
joshua

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2004 4.2 Allroad
2000 2.7t S4
The Arizona Audi Car Club
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