If you hadn't already replaced the Temp II sensor, that's would I would
have recommended. I have seen replacement ones that were bad from the
start, so you might try another Temp II. Also, make sure contacts on the
Temp II are clean.

This just screams Temp II. Disconnect it and see what happens. When I
disconnect mine ('86) the idle raises to 3000 RPM.

Of course, check grounds, check grounds, and check grounds.

Finally, swap ECU.

j

On Thu, 23 Nov 2006, Cary Chiang wrote:

> Happy Thanksgiving, folks!  I'm having trouble with an '87 Syncro (purchased
> with a locked-up engine), and a recently installed used engine (no history,
> bought as a core).  When first installed, the engine seemed to run decently,
> other than a slightly high idle of 1,200 RPM.  Now, however, after a
> very brief warm-up, the idle is rapidly cycling between about 1200 to
> 3000 RPM, at about 1 second intervals.  The throttle body micro switch
> is set properly, and tests good with an ohm meter.  There is 5 volts
> at it's connector, as required.  The idle stabilizer valve on top of
> the engine hums and vibrates when the ignition is on, as it should.
> It and the idle stabilizer control unit were both replaced with ones
> from a known good vanagon, to no avail.  When the idle stabilizer valve
> is disconnected, the idle stays consistent at about 2,200 RPM.  The
> timing is properly set, and the Temp 2 sender replaced with a known
> good one.  The engine runs worse when the O2 sensor is disconnected,
> indicating that it is functioning at some level.  It has not been replaced.
> There is a random misfire or stumble (cough), but there isn't any excessive
> smoke indicating a rich-running condition.  Turning the large diameter
> idle speed screw on the throttle body clockwise will reduce the idle
> speed slightly, but the surging continues.  Other than replacing the
> ECU, I'm out of ideas.  Any advice or help is greatly appreciated.
> Thanks in advance!
>
> Cary
>
>
> --
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