paalw

I found this after removing air filter box on my new to me S3. Anyone know what this plugged vacuum hose is for, and where it originally ends up? The connected end is the top one of the two coming from the throttle body, looks like it isn't completely seated, see photo #2. Any idea why it's been plugged in my car?

bureau13

Not sure if this is on your end or mine, but I don't see any photos...

paalw

Hm, strange, I see them and the links seems ok?

Anyway, I look in PET and it seems like this line should be blocked off with a small rubber stopper at the throttle body. A bit strange that there is a long hose with a screw in mine(??), but I guess it makes the same purpose. I should get a 930 110 292 00 to plug it at the TB...

davek9

It's one of the front two that should be blocked, in a "stock" config both firewall facing are used, especially the one on the Drivers left.

That is the one that is variable and should feed the 7 way, going to the two Fuel Rail Dampeners, FPR, Auto Trans and ECU's (connector is on EZF), and Fuel Tank Vapor system switch on the cross bar or on an '85 its fender mounted
The Right side is for the Fuel Tank Vapor system.main feed from the Temp switch on the Head.

The Front two: Drivers Left is blocked and Drivers Right goes to the CAT's Gulp Valve that switches Air to the CATS or Air Filter.
If you do not have CAT's and the Air pump is removed it can be blocked at the source (Auto stores sell small vacuum caps).
If you don't wan't or use the Temp controlled Tank Vent, then the Right Rear facing one can also be blocked, but you will need to block/reroute the Charcoal filter back to the Tank Vent.

Dave K

paalw

Oh, my bad, I see you are right! So that's strange! Why would anyone block that line? Does anyone have a photo of where the 7 way distributor is located and how it looks?

davek9

It usually lays in the bottom rear of the "V" soaking in old oil and dirt and heat
When I redo the Intake system and vacuum lines I make some a bit longer so as won't sit directly on the bottom

Dave K

paalw

Ok will take a look next time I am with the car and see if I find it. But it sounds like it would have some serious effect on a lot of stuff to have that line blocked? Can you think of any good reason to do that?

I noticed the car had a bit too high idle when warmed up, around 1000-1100 (seemed ok when cold, 750-800), and the (auto)gearing was not very smooth, kind of slammed into gears. Could this have something to do with any of those two things?

davek9

Absolutely, Auto Trans need to know engine load and so does the EZF for Ignition advance/retard, all the parts I listed need a variable input.

As for trouble shooting your issue, from the pic, you need to remove the Intake and clean and inspect all rubber the bits.
Also you can block off anything that is fed by vacuum, most likely one or more of the vacuum pots are leaking.
Example but not inclusive would be: HVAC, Brake Booster, Cruse Control, Auto trans, etc.,

Dave K