vaccum lines on 1998 2.5
 

Chasing vaccum leaks on my 1998 Boxster 2.5.
i have a vaccum line from my left rubber sleeve on the plenum (Seen from behind). It is delivering vaccum to the fuel pressure regulator. The right rubber sleeve also have a similar hole in it, but this is blocked of with what seems to be a factory made metal stud.
Is this setup correct, or has someone modified the system, and if yes, what problems could this cause?

Look for my posts about vacuum diagram, will have pictures to show you what connects to what. also, another thing that will help you is to download the Porsche PET from their web site. It has all of the parts, pictures & part numbers. Easier to see it then describing.

Pictures also help with what you are referring to.

Sounds like someone has messed/changed things but hard to tell from just your description.

Is your car North American or Euro? Tiptronic or manual?

As a 1998, it should have vacuum from the plenum boot to the fuel pressure regulator.
If it's North American, should have a second vacuum source with a black and white check valve going to the secondary air injection system. If it's Tiptronic, that vacuum source should also go to a valve for the transmission heat exchanger.
It should not have the second cross-tube and resonance valve that is shown in many diagrams (for the 2.7L and 3.2L engines).

Vaccum line
 

The car is Euro spec, and not tiptronic. Maybe it is correct with just one vaccum line going to the fuel pressure regulator then?

Like I said, get the PET. It will help you.
https://www.porsche.com/central-eastern-europe/en/accessoriesandservice/classic/genuineparts/originalpartscatalogue/

Same conversation with another person this past week. Post is: Car Dies