Posting this to all the Volvo forums I can find, this is stumping everyone.

I have read all the FAQs.

Car is a '92 740GL w/Regina system

Sometimes it starts and idles fine for 15sec or so, then idles @ 2K RPM. sometimes it starts hard and wants to idle low. Sometimes when you plug the IAC in you can feel it opening and closing, and sometimes when you plug it in you don't feel anything (no power to the IAC?!).

Tried this with the original IAC and a Bosch which I jumpered (and hooked up to feed/vacuum hoses), saw the same behavior with both. So good news is, if you need to use a Bosch IAC on a Regina system, you can kluge it in if you have to.

Have run both IACs off a power supply to test them and they both operate flawlessly.

Have cleaned the TB and this http://forums.turbobricks.com/showthread.php?t=35053 (after the idle issues were noticed).

One thing, the IAC only seems to fail to operate when it's fully warmed up - so far.

Any input is greatly appreciated. TIA!

Dave

Check the throttle position switch and make sure it is "clicking" into idle setting when you close the throttle. It's the click that tells the system that the IAC needs to keep the engine at idle speed. Simply HEARING the click may not be proof that the switch is functioning properly - checking continuity across the connector pins is a better method. The 700/900 FAQ has instructions for adjusting the switch and verifying it's functioning properly.

What sort of fault codes are you getting, if any?

Besides the click and continuity test, check the linkage that connects the throttle spindle to the wheel/pulley that guides the throttle cable, kickdown cable, and a third cable (I don't recall what it does).

Get your nose in there: Disconnect this linkage at the spindle/spring throttle plate side, linkage is relatively vertical. Move the spindle and hear the click, note how the mechanism works. Just as spindle lifts, click is heard.

Now make linkage longer by loosening the nut and holding the center of the linkage with a crescent type wrench. The idea is to make sure the linkage is not pre-maturely moving the throttle spindle. It could be moving TPS past the click; that is the linkage robs any adjustment made for TPS. Think of the linkage as pushing away the two parts it connects. It only takes less than 1mm of upward motion to make click.


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I own a Volvo or Does Volvo Own Me? Try the easy to search Expanded Style FAQ Index http://40mph.com/Brickboard_700-900_FAQ_Expanded_Index_Version/

"throttle stop" is a better name for "spindle" for what I am referring to.
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I own a Volvo or Does Volvo Own Me? Try the easy to search Expanded Style FAQ Index http://40mph.com/Brickboard_700-900_FAQ_Expanded_Index_Version/

Thanks, going to check that and the ECT (another helpful soul pointed me to this http://www.brickboard.com/RWD/index.htm?id=1432445&show_all=2 ) Cheers!