<E30> 325i hunting idle

["Frank Ciotti" <frankc@xxxxxxxxxxxxx>]

I am having a problem with the idle on my '86 325i.  It started out with the
idle vacillating from about 700 to 1200 RPM for the first 15 seconds after I
started the engine on a cold morning (cold being ~40 degrees F in Houston).
Today, however, it got worse.  The idle is now fluctuating even when the
engine is warm, and the RPMs are falling so low on its downward drop that
the engine almost stalls.

After referencing Bentley, here's what I've checked so far...

Coolant temperature sensor - resistance in correct range
Idle and full throttle switch - continuity good for idle and full throttle
Idle air stabilizer:
	- correct resistance between appropriate terminals on stabilizer.
	- 12 volts between center terminal & ground at harness connector (correct)
	- open and 12 volts between center terminal and the two outer terminals at
	  harness connector (wrong! - should be 10 volts for both)

Question: Bentley says the ignition simply needs to be on (engine not
running) to check the voltages to the stabilizer. However, I spoke to a
mechanic today and he said the engine must be running to perform the test.
Is he correct?  If not, shold my next step be to check for continuity
between the outer terminals of the harness connector and terminals 4 & 22 of
the Motronic connector?

One note, this engine exhibits typical lean mixture characteristics when
cold - hesitates badly if I tap the throttle.  The hesitation goes away
after the engine warms up (5 minutes).  At least it used to until today, now
it hesitates all the time!.  I still suspect either a vacuum leak or clogged
injectors.  Anything else suspect?  Oh, I don't think it makes any
difference here, but this is euro 325i.

thanks,
Frank Ciotti
86 325iC euro

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