curious warm-up erratic idle + high idle

[Clio320i]

Hi guys. I've been searching a while and ultimately decided to start a new thread because no one seems to have experienced exactly this:

When starting engine at anything but full operating temp (or nearly so), it starts like a champ and then the idle fluctuates between 200-1400, gradually evening out over the course of about 30 seconds or so to an idle speed of 1200, which then gradually slows down over the course of another minute or so to 900.
If I drive it during the first few minutes, it's totally normal. And usually driving it off will make it so the idle fluctuation disappears more quickly.

Some data:

Fuel system recently was "cleaned" -- not sure what that entailed exactly.
WUR was replaced after the above procedure with a used one. (why? idk. Apparently because fuel pressure was too high when cold)
Cold start valve was replaced with a NEW one a few years back and should still be good.
I checked fairly extensively just now for vacuum leaks and found none.
In all other respects, the motor runs very well. Pings a bit on mid-grade fuel when very warm. On rare occasion when driving normally (like 2K-3K rpm around town) I notice what seems like a misfire or a little flat spot or something. It is not consistent.

Impressions, anyone?
-Susan

[epmedia]

It's probably just a tiny bit rich.
When it's cold and doing it's idle hunting, you can experiment by opening a tiny vacuum line to see if it settles - to verify if a tiny bit rich.

Or, just tweak the afm about 1/16 turn CCW and see how that settles it.

Robert

[pommeree]

Try the exact same cold start procedure as you described above but with the O2 wire unplugged. (The disconnect is low on the firewall beneath the distributor)
and see if you get different results.

You can get a general reading for your mixture by connecting your O2 wire to a digital multi-meter and taking readings once it's warmed up.
The single wire O2 will give a 0.5v reading at the ideal mixture but anything above or below will peg at 0.9V or 0.2V respectively.
So If the meter is jumping back and forth consistently, you've got a good mix.
Otherwise, make adjustments (see FAQ) in like 1/16th or 1/8th turns max and re-test.
Some folks can do it with the engine running but I could only adjust with the engine off.
Once you restart, give the engine 30-60 Seconds run time before re-reading the meter.

[Clio320i]

Thank you both! I will go do these things tomorrow when it's not PISSING DOWN &@!#%& RAIN ALL FREAKING DAY and report back. Yes, I love Portland.

(later)

Sooooo naturally it didn't DO this problem today. In other news, I fixed the heater blower motor so I can have defrost. Yay safe night driving

Now for beer.