Rough idle - Cold Start Valve problem?
 

I have an 83 SC and for the last 2 mornings the car idles real rough. The idle problem is only at the first start of the day, after that it runs and starts fine.

No smoke or other indication of a problem. In the past month car has a new WUR, fuel filter, fuel pump. All done not related to this problem.

Thanks for the help.

I was going to open a new thread about this, but this one seems appropriate enough. For over two years of owning my 911 SC, I had been experiencing cold start issues and low idle until it smoothed out when the engine reached op. temp. Just recently, I decided to really delve into this. I took the WUR apart to see if there was debris. Totally clean. Put it back together. Scoured more Pelican threads. Then, I found a couple of short posts where the guy simply removed the WUR and knocked the plug. You'll see an approx. 1/4" round thing that is recessed from the rest of the surface of the device. I simply tapped the plug so that it moved approx. .003". That minuscule amount made all the difference in the world. Car starts right up and it goes through its proper warm-up cycle. Most guys on this board will tell you that you should invest in a CIS gauge before you go messing with things. They are right. However, I'd be willing to bet that the majority of cold start issues stem from the WUR. Removing it is simple and so is knocking the plug. If you knock it too far, you can even push it back. This experience has lead me to conclude that I will make my WUR adjustable and will eventually invest in a CIS gauge. But, in the meantime, you may have everything you need to make a simple adjustment and fix your idle issue.

Oh yeah, it took a couple of tries before I found the "right" position for the plug. I knocked it too far on my first attempt and I experienced the same "idle hunt" as you. I simply pushed the plug up and it solved the problem. BTW, you need to open the WUR up to be able to push the plug up. I hope this helps.