928s4newbie

Hey guys, I'm a total newbie trying to step outside of my comfort zone and took on a 1987 Porsche 928 s4 project (this was my dream car when I was a kid). Currently doing the intake refresh and replacing the vacuum lines. As someone who has never done a car rebuild I took everything apart quickly and didn't take enough pictures. Now I am feeling a little lost when connecting the vacuum lines to the intake. (34", 28", 12")

When looking at the vacuum diagram it shows 3 lines but my intake has 4 nipples? Attached are the photos of the diagram and my intake. Also, curious if it matters which vacuum line I attached to which nipple on the intake? My initial thought is no but I want to confirm.

Thank you so much for your help.

Jonathan R

Hi, the 4th vacuum port - the 'unused' one you show on the underside of the throttle housing - is for the air pump diverter valve on cars with an air pump. If your 928 has no air pump this port should be securely capped -i.e. blocked off.

Best regards,
Jonathan

Smitje 928

Is think you have a manual transmission car? I did the system on my '87 S4 but mine is an automatic; let me know if I can help by posting a few pics.....

928s4newbie

Mine is a 1987 928 s4 w/ auto. If you have time please post any additional info you have Im going to the Hangar to work on the girl today. Hoping to get her running by the end of the week. Thanks in advance.

Your 928 is gorgeous. Those wheels really dress it up nicely.

Jonathan R

Re >>> Also, curious if it matters which vacuum line I attached to which nipple on the intake? My initial thought is no but I want to confirm. <<<

Do connect the vacuum lines to the correct ports, as shown on the diagram and various rennlist threads, if for no other reason than that it makes life easier fault finding in future.

Best regards,
Jonathan

Mrmerlin

line 34 connects to the port that is facing to the front on the top of the throttle body.( TB) to the EGR valve.

Line 28 connects to the bottom of the TB. to carbon canister.either one should work here.

Line 12 connects to the port that faces to the rear on the top of the TB this is for the 7 way splitter, for the dampers and FPR and trans modulator.

NOTE the hard line rubber connector to the port on the TB is straight not an elbow as pictured for the two ports on the top of the TB,
the port under the TB gets an Elbow

NOTE make sure the flappy stop is properly positioned so the flappy plate wont bind.
Make sure the vent hose from the oil fill base is not pinched between the intake and the head this is easy to do if your not watching this hose before you bolt the intake down

Smitje 928

Thanks for the compliment, I am very happy with the result!

I attached the document I wrote for myself when I took the system apart. I still have the air pump, so that got connected as it should have been (which it wasn't when I took everything apart).

Unfortunately it is in Dutch, so maybe Google Translate or something like that might help?

Good luck!

Geo55

That is the same diagram that I used when I did my upper refresh on my 87 auto. Don't panic, just take your time and it will all come together. look at the lengths on your digram, that will help. I also have a few pics if you need them.