Re: High Idle problems

[rdh@sli.com (Robert D. Houk)]

     I'm not sure that the screw in the top of the throttle-body is the idle
     level control screw, I think it's a stop for the throttle. There should
     be another screw on the linkage on the side of the throttle-body for
     setting the base idle RPM. Check Bentley to be sure. Undoubtably varies
     from model-to-model, but I'm pretty sure that the screw on top is NOT the
     idle adj on ur-Qs and 4000Qs.....

I think you've got it backwards. There is a screw that acts as a throttle
stop point. This is a "factory" adjustment and should be left alone. Among
other things, it can affect the "idle" switch engagement as well. (I think
it is a trap put there to catch unwary 'Muricans who think adjusting the
idle is a simple obvious and straightforward adjustment of the usual throt-
tle stop screw, like in "normal" cars!)

The idle adjustment is a small brass screw in the top of the throttle
body, pretty much centered over the throttle plate, as I recall. This
brass screw "bleeds" air around the closed throttle plate, setting the
base idle (nominally the throttle plate is completely closed off at
idle). The idle air adjust screw also has an O-ring that probably needs
to be replaced . . . else a) unmetered air "leaks" in and really screws
up your idle; and b) the screw itself vibrates loose (never tighter, al-
ways looser/falling out!) and leaves you idling around 3000rpm... (I dis-
covered this the usual hard way! As tempting as it is to use this readily-
accessible orifice to induce ether into your intake system, don't do it,
the ether nicely and completely cleans out your old dead O-ring!)

Usual qualifier: This is specifically for '83 UrQ ...

					-RDH

P.S.	Since I guess the original query was about high idle speed (OK
	cold, high warm, which is kinda the opposite of the usual problem
	where it idles OK warm and not cold!), I will hypothesize (read:
	babble some more in order to avoid going back to work) another
	possibility. On my car, there is a "cold-engine idle air bypass"
	valve that meters extra air for idle, in theory just enough extra
	air to idle at normal idle speed when the engine is cold; in prac-
	tice it usually idles a little bit faster. It's an electrically-
	heated bi-metallic air flap that gradually closes off as it (as
	opposed to "the engine") warms up, so that after a minute or so
	your idle air is set solely by the idle air adjust screw as de-
	scribed above. Now...if this gizmo were not working, then the only
	way to get a cold idle that doesn't stall out would be to crank
	up the idle air adjust enough that a cold engine keeps running;
	by the time the engine was "hot", you would have gained several
	(or many) hundred rpm over the "cold" idle. (Actually, I think
	this gizmo is called the Aux Air Valve, or something like that,
	cleverly disguising its real purpose in life). I don't remember
	the original poster's car/year/etc., so don't know if this is
	how "his" system operates, above usual qualifier still applies!