Cold start bouncing idle video

[Hotwatermusic]

http://www.youtube.com/watch?v=NzKxIjdSFS0
83 911SC, no O2 sensor, just put the engine back in about a month ago. New plugs, fuel injectors, CIS cleaned and rebuilt, most hoses replaced, valves adjusted. What would cause the idle to bounce like this--especially like it does starting at the 27 second mark? Only happens on cold start-up, so I would assume the WUR, but I know enough to know I don't know enough. Any ideas?

[Hotwatermusic]

I searched a good while but could really only find guys with a bouncing idle between gear changes, or much later model cars having the problem--but none that I found were on cold start-up. Anyone have any thoughts as to what's causing revs to jump like this?

[ossiblue]

From your description and video, it appears to be an overly rich cold start fuel mixture--that's what usually causes the idle to hunt as does yours. First step is to check the cold control pressure of the wur and compare it to the charts for the particular wur model and ambient temperature. If the pressure is too low, it will cause an overly rich mix which results in the hunting. If the symptom goes away when the car warms, that tends to further confirm the wur/cold pressure setting.

If you don't have a fuel gauge set, get one if you plan to do any self-diagnosis on your car. Do a search for fuel pressure test, and read up on the procedure and specs to get comfortable in approaching the testing yourself--it's very easy with a good gauge set.

Let us know what you find when you test the cold control pressure, please.