No subject

the ISV is disconnected ... this should not be the case.  You should notice
the idle speed decrease noticeably ... and perhaps even stall ... when the
ISV is disconnected.  I'll bet that the screw in the throttle body that used
to be for the idle air bypass valve is not snugged down tightly.  If air is
bypassing the throttle body via that channel it does not give the ISV
controller sufficient range to be able to modulate the speed.  My '85 4kSQ
was set up this way by a PO.  I never could get the car to idle properly ...
even after replacing the ISV.  Once I tightened down the bypass screw the
car would sometimes stall when slowing to a stop ... like at a traffic
signal.  The problem was that the ISV would get sticky and be slow in
starting to operate after sitting idle for some period.  My thinking is that
the car was stalling in this way before and the person that "fixed" the
symptom simply opened the bypass valve.  

HTH!
Steve Buchholz
San Jose, CA (USA)

> 
> My ISV is acting up again...I think.  With the wires attached 
> to the ISV, 
> the at-a-stop idle will range between 1000 and 2500 RPM.
> 
> Unplug the wires on the ISV and the runs with NO idle 
> fluctuation.  Now my 
> question is: is there a sensor that feeds the wires that plug 
> into the ISV 
> that could be sending the wrong message or is the ISV just 
> not doing its job 
> correctly?