Hole on top and hole on bottom! The spinning tunbler in center which I assume goes slower or faster to control idle! Black knob on it that when screwed out allows air to be sucked in there as well, which I assume is probably for some testing process, I would assume you do not want unfiltered and uncontrolled air flowing into the intake as it would act like a seal was leaking. I will close it and report back if no one has answered by then! Thanks for your input on the rest and getting my brain to click on this one. I would assume you want a sealed intake, or as close to it as possible....

Edit: Update! Closing it in my case makes the idle much much worse. It must need to have some air so it works properly! Oh well, I think I got it better now but we will see. Raised it a hair and re-adjusted mixture and she is idling almost perfectly!

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....