You will probably need a pressure gauge to set the warm-up regulator. It is, most likely, rich and the "pin" will need to be pulled up.

If you don't want to buy a pressure gauge and want to try to fix it by trial and error, try this.

Drill and tap the pin, like Tailpipe (if you can read and understand his unpunctuated ramble) says. Measure how far down in the hole the "pin" is and pull it up 1mm. Try this for a few starts. If this is the wrong way, you can always go the other way.

 

That's not really necessarily true. All that really means is your cold start is too rich. This could be because it's too rich. It could also be because you aren't getting enough air.

At any rate, what you should do, because even if your WUR is perfect this is a good first mod if you plan on ever modding the car - send your WUR to Brian Leask and have him do his thing.

http://members.***.net/930wur/

 

Depending on how cold it was when you looked in the aux air valve, I would have thought it would open somewhat- what temp was it ? Its just a flat disc that rotates due to a bimetallic strip (against a spring) and opens/closes a through hole to allow extra air through.
You really need to check the pressures to know whats going on here. Most times the WURs clog with crud, which forces the control pressure high, and they go lean - going rich is unusual in my experience.
jp 83 Euro S AT 52k

 

^The aux air valve WAS open when cold: I was just too dumb to notice. My mistake. It moves nice and easy.^

^^I will modify the pin and try to pull it up, like Greg says to.^^

Here are a couple of links to the procedure. The first link describes how to do it, the second link shows the reasoning behind the adjusting, and the third has pics of the procedure (though he doesn't use the 1.5mm drift pin "locator" at all).

http://porsche928forums.com/viewtopic.php?f=25&t=540
http://porsche928forums.com/viewtopi...=543&hilit=wur
http://forums.pelicanparts.com/porsc...-got-pics.html

Will changing the pin height alter the A/F ratio when warm? From the cutaway pics in the second link, I would think not.

 

Seeing as the WUR was once OK, it shouldnt need this sort of adjustment unless something serious has changed. I would strongly suggest that you get a gauge set on the system before moving any settings that will be very difficult to recover. Going rich cold is unusual IMHO. If you think the aux air valve is open, try starting it cold, and crimp the aux air hose (pliers or fingers) , both after the valve, and before , and see if it reacts - should stall or run slower. If it doesnt, air is not going through - check where the before hose goes for kinks or some problem.
Before I did any adjustments to a wur, I would open, and ensure there are no blockages or crud inside anywhere - the gauze filters tend to fill with lint and dried gas etc. One of mine had FIVE (5) layers of brass gauze under the inlet banjo. Usually this pushes control pressure UP, which causes a lean mixture.
jp 83 Euro S AT 52k

 

I have never done that on a Porsche, but on the volvo's and MB's they tend to run lean and we would tap the pin in, due to wear on the spring and washers under the plug.
I never would have guessed that on a 928 they would have worn the other way.

 

Any change to warm control pressure will alter the a/f ratio, until you adjust the screw on the air plate arm.
jp 83 Euro S AT 52k

 

Actually, I don't know if it ever was.

DEVEK sold me a euro-S car back in about 2005-6 that had many issues (never being register-able being one of them). Susan assured me that the compression was good, and the intake had just been re-sealed. I drove that car for a sixty-mile trip back to my house. It had a pretty decent dash fire on the way, while I was doing about 95-100mph on (busy) highway 101. Smoke everywhere. And the windows were non-op! So I had to open the door to flush out the acrid smoke (it was so thick that I couldn't even see out of the windshield!) and steer hanging out the door and choking while negotiating the other cars.

So suffice to say, I didn't trust the car too much after that! I stashed it under a tree for a while.

After that, it was started only once, for a move to Dan Brindle's house (no fires this time), where the car was dismantled, parted out, and chopped up. I R&R'ed the motor some (seals, headers, clutch, etc.) while it was there, then eventually installed it in my car in 2008-9. I didn't start it until August 2009. Then I stored the car for another year while I moved to Texas.

So that is only a handful of starts in over 3 years sitting. So I really don't have a baseline to start with. This will be the first winter I've had with the car. It always had the idle surging after the transplant, only it was always warm weather, so it didn't seem too bad.

 

The car does smell rich before it has warmed.


Sean R said the same thing at 3rd Coast, about tapping the pin in.

 

I am just trying to suggest that a good clean of the works of the WUR might obviate the necessity to adjust anything. Surely you have experienced cases where you thought you were in for an overhaul of something, but once you looked inside you found it was something simple to fix? Crud inside a WUR can really screw one up. Some guys have loaded the tank with a cleaner like Berryman's, and jumpered the pump relay and left it circulating for a period to dissolve crud and clear out things, with good results.
jp 83 Euro S AT 52k

 

I would take Greg Browns advise long before anything i say worked on a volvo.

 

I guess that can't hurt. I have run a few bottles of Techron thru the system, but that was a while back. It's not like the car is undrivable the way it is now, anyway. And it's good heel/toe practice.

I kinda thought the MM Oil acts as a cleaner, though. I run that in every tank.

 

Concur with jp... cleanliness is next to godliness in a pressure sensitive system like cis; pump, accumulator, wur, distributor, aux air valve, temp sensor contacts, all the hoses in between. I've had excellent results just getting the stock stuff clean, de-gunked, exercised. I'd drop some chemicals in the gas tank and empty it on a twisty road. You'd be amazed how much better it runs when you get home.

 

I've tracked the car 3-4 times over the last several months, so stuff definitely has been sloshed around. I'll run some more cleaner through.

The car sure liked that 93 octane gas I bought in Marble Falls. Still surged when cold though.

 

Making CIS work with lumpy cams has been something of a feat, and a learning experience. While my knowledge is MB, my experience says that when CIS surges at idle 10:1 it's an amount of air issue, not a fuel issue (I know that seems silly to say, because they go hand in hand, but what I'm getting at is you should be looking at places that control idle air distribution rather than fuel distribution).