does this go Here?
 

I have pulled the Air plenum and throttle body off of my 84. When doing so I found a large nipple on the side of the throttle body with nothing attached to it. Underneath it I also found a short cap like piece that looks like it may have been attached to it. I have provided picture too. I know how we all like pictures! :)

http://forums.pelicanparts.com/uploa...1389735785.jpg

http://forums.pelicanparts.com/uploa...1389735819.jpg

It appears that it goes like this.....

http://forums.pelicanparts.com/uploa...1389735861.jpg


Just need someone to confirm what I suspect!

Dan

I would say it needs to be plugged up for sure...especially if there is not a strange little hose that curves down and seems to want to plug into it. If I had mine at the house, I would go out and check it for you. I have an 84 as well. Plug it off and it will run and then do some research as to what actually goes there. When I get mine back to the house in about a week, I'll reply if not already answered. I would use a better plug though...that looks pretty rigged ;)

That is I think where the vacuum limiter goes in early cars and where the idle control goes in newer ones. Idea is that if you down shift with the throttle closed the vacuum may be sufficient to prevent combustion and cause a misfire.

Mike is correct, also called a "Decel Valve" and it's purpose if keep from backfiring upon deceleration. My S also did not have one but in order to comply with the Calif Smog Nazis, I got a good used one from 928 Intl and installed it.

That is a "huge" vacuum leak spot so if your going to ghetto plug it. Use new rubber/silicone pieces.

http://forums.pelicanparts.com/uploa...1296362876.jpg

http://forums.pelicanparts.com/porsche-928-technical-forum/588682-vacuum-limiter-decel-valve-vac-route.html

I have it removed on my car. It has never backfired. It does however make driving a bit more harsh. It keep the rpms from slamming down after a lift, ans smooths out shifts. Also when I go from zero to full throttle at low rpms my car has a single studder, that it didn't have with that valve.

It doesn't appear that I have a vacuum limiter. Maybe it was removed by the PO. I think I am going to plug it up tight, at least for now. once I have her up and running I will see if it makes sense then to install it.

I wouldn't bother unless required by your state smog. As Pete says, it doesn't do much anyways.

I believe the vacuum limiter/decel valve was equipped on the 5spd cars but not the automatics, right?

that would make sense, Mine is an Automatic

My automatic had some caps on those ports as well. Can't confirm that it was only manuals though.

http://i.imgur.com/5jag2qWl.jpg

My 82 auto has those caps. They have a part number I believe, since on automatics they are all capped (I'm pretty sure). I replaced both of mine when I was trying to hunt down a vacuum leak.

928sRUs can provide the factory caps. I don't have an 84, but the one you have looks really long to me. Also, I can't tell if the top one in your picture is capped at all.

My Euro has a Decel Valve and it's an Auto.

My '79 Auto has them as well...I'm in California.

LOL, you can see the oil line on the bottom like after a flood

Nah, that's age rings like on trees. :rolleyes:

Thanks for the Pic Brad. Very helpful The top one on mine does have a cap on it that is in poor shape and has a screw clamp on it. The lower one was just kicking around on top of the engine. I am going to replace both caps.

I just received a box of parts from 928'sRUS that include some relays, and the fuel line Kit. kicking myself for not adding the caps to the list! Looking forward to putting things back together. ...Dan

the Fix
 

went to local auto parts store and picked up a assortment pack of "bypass Caps" there are about 6 rubber caps and two of them fit perfectly and only cost me $4.99. feeling good about my small step forward. Thanks again for the help!:cool:

Dan

http://forums.pelicanparts.com/uploa...1390174072.jpg

That actually looks pretty damn good. Nice find. Maybe post the part number, place you bought. Pics of the Assorted pack and post in the Common Fixes Thread. I'll index it.

I did the same thing. They are a common plug most real auto stores have in a assortment box.

Pete, I can assure you that it didn't keep those oil lines hahaha.

http://i.imgur.com/jJDO2tNl.jpg