sprie

I have looked at a couple of the vacuum hose diagrams, but I am still not sure which ones I am looking at. I have checked the 4 hoses that connect to this connector in the photo (this connector is just by the brake servo, attached to the firewall) - and the extra hose in the picture is part of my test kit:

1. The “feed” hose from the front of the engine has a healthy vacuum when the engine is running.
2. The black hose at the bottom holds good vacuum.
3. The white hose in the middle needs lots of pumping but holds the vacuum.
   
4. The grey hose at the top heads under the fuel rail and holds no vacuum.

I am guessing that the white hose in the middle is heading for the reservoir?

What are the other hoses for? In the short term, I guess I might as well cap the connector for the grey hose, so that the other hoses have full strength?

Are any of these heading to the HVAC – as my heater controls are working but might be slower and less effective than they should be?

Rob Edwards

Here's an annotated diagram from John Pirtle's excellent writeup on the S4+ HVAC vacuum controls:

Darklands

Is somewhere a picture of this area from a 928 S?

Mrmerlin

NOTE picture for the 928 S is the same except the port for the flappy supply is plugged.

Darklands

Thank you,
in the cross on my 86 S is a bolt, so it's on the right location!
I must look if the Y connector is there or someone blocked the cruise control.