dont know if i'll be much help here but i'll try . i've seen this question for a few days now and have been trying to find some diagrams or pictures but have not been able to .
the vacuum hose that you asking about per your other question is for the fuel pressure regulator . i looked at a car in the shop today and it looks like the hose plugs in under the intake near the throttle body . yuo may need to remove the throttle body to see it ( or feal it ) if left off it could cause a checck engine light for a lean mixture because of a vacuum leak or maybe a rich mixture because the pressure regulator has no vacuum so it is giving full pressure .
let me know if this was at all helpful , ill do my best with you to get to the bottom of this .
BMW Technician
12 YEAR MASTER TECH