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Ladies and gentlemen, long time reader but M.I.A. for a while (darn kids!)
I have an 82 320i/4 with 155,000 km and manual transmission. I do all the regular maintenance, oil changes, spark plugs, wires, air filter, distributor cap and rotor, etc...the car is in great shape.
I have not adjusted any fuel or air mixtures or messed with the timing. (YET!)
Living in Southern Ontario (Canada) we encounter some temperature extremes (-20C to +38C)
Proper idle at warm up is important for drive-ability.
Doesn't really matter what day, but when I start my car cold, it starts up to 1100 rpm then after 10 seconds or so, will not hold it's idle (it will stall) unless my foot is on the pedal. I hold it at 1000 rpm until the temp needle passes the blue almost to the first line (1/4 mark I guess) then, something happens. The rpm zoom up to 1300 or even 1500rpm. Take my foot off the gas and it idles.
Now, another problem is warm running.
While stopped at traffic lights (engine at normal operating temperature), the rpm's hunt from around 500 to 1100rpm. The engine just accelerates and decelerates as if I am pushing and releasing the gas pedal. The idle is quite erratic.
Clutch in or out has not effect.
No vacuum leaks found.
Does it look like I will be taking my WUR apart?
Any direction would be appreciated.
Cheers everyone and Happy Holidays!

I'd start with checking what exactly is happening using an exhaust gas analyzer, even just a simple CO meter may suffice, wouldn't be surprised your fuel mixture is lean-ish over the entire range.

Also check for any intake vacuum leaks. Any other issues, or does the engine run smooth and feel strong?

You say that no vacuum leaks are found, did you spray some ether or starting gas at some junctions? When the engine shuts down or hesitates because of that, you have a leak.

I found my wur stick, once freed and set to correct cold position, using, from memory, a 2.7 mm drill.
Starting and idle vastly improved. Instructions came from my trusty Haynes.
The Solex is the most complex carb I have ever seen, so treat with care and instruction.

I'll look even harder for a vacuum leak. This was my suspicion as well. I hope is isn't that darn tee connection uunder the intake manifold. It is such a pain to get at without removing the manifold.
And yes, it does seem to be lacking some power but not at highway speeds, just off the line.
Oh, by the way, any easy way to take off the fuel lines that go to the WUR safely. I really don't want to have a fuel leak after I re-assemble it. Also, any diagrams showing how to hook up fuel pressure test guages to verify cold, running, etc pressures?
Oh, didn't mention......black soot deposits in the tail pipe. May be too rich. Plus I have a non-oem main fuel pump.

I get the idea he means the choke valve (carb model, instead of WUR) as this has to be set to an approx. 3mm gap indeed.

Sorry Jeroen,
You are correct, I meant the "heat sensitive bypass" on the Solex carb, the cold gap should be 2 to 2.4mm, on the carb model. A senior moment.
Mike

Hey everyone, it's a 320i.