Located below ignition distributor, part # 055 131 851 C - at what temperature coloses/opens ? Any info ?

Far as I can tell, it closes 2-3 minutes after startup. No clue on the temp.
HTH

It's a 'vaccum' switch, as it were.

When up to temp, it either turns off a connection between the intake manifold, and the warmup regulator vaccum port.

Under 'full throttle enrichment' the connection to the control pressure regulator allows boost pressure to slightly affect the fuel mixture.

I've seen an excellent diagram (and perhaps writeup) of all those hoses and valves and such.

Found!

From Phil Payne's site (http://www.isham-research.co.uk/quattro/) :
<img src="http://www.isham-research.co.uk/quattro/images/wr_hoses.gif">

I think the thing you are asking about is item No. 24 (but may look physically different) at the back of the motor, kind of under the distributor.<ul><li><a href="http://www.isham-research.co.uk/quattro/wr_hoses.html">Operation, and Temp specs</a></li></ul>

Thanks for the link.

When I replaced mine last summer (one of the ports was broken when I got it) I hunted all around. A friend found one on the Audi parts network in Chicago. It was almost $100, and I ws told it was the last one in the country. I have no clue where else one could find such a rare part.

in boneyards - I bet he has 10 of them - i always joke with him that it's his favorite part....

Brandon
'84 ur quattro 20Vt

Mercedes, brand new around $20.

Thank you. This is what I was looking for.

Read under the heading "Control Pressure Regulator" in the link. Diagrams at the end are good too.

In fact, the whole writeup is good.

So go read all of it! :-)<ul><li><a href="http://homepage.ntlworld.com/jh.666/wr%20fuel.pdf">http://homepage.ntlworld.com/jh.666/wr%20fuel.pdf</a</li></ul>

This will allow me to keep my CIS system healthy.

Thanx!