Very High Idle ISV Problem

[Christopher Flanner]

When I remove the ISV and try to blow through either connection, I can tell
it is definitely closed.  It really seems like vacuum is opening it when the
engine runs, though.  I have visually confirmed that the spring returns the
plunger to the fully closed position.  The plunger moves freely and the
valve is clean inside.  As I've mentioned, even with ISV disconnected,
pinching the ISV hose connections brings the idle down to a normal range.

My idle switch checks out but I haven't verified a good connection to the
ECU.  Someone mentioned that the fuel should cut off at 1800 rpm when the
idle switch is closed.  Other sources say the idle can still reach 3000 rpm
with the idle switch closed.

Thanks to those who have written!  We'll figure this out!

Thanks,
Chris






>From: JShadzi at aol.com
>To: cflanner at hotmail.com ("Christopher Flanner"), quattro at audifans.com
>Subject: Re: Very High Idle ISV Problem Date: Mon, 17 Feb 2003 18:31:28
>-0500
>
>The spring holds the MC and turbo ISV closed, if yours is unplugged and
>open then its likely defective.
>
>Javad
>
> >Please help me to get some basic ISV understanding. =A0The engine is an =
MC
> >from an '86 5ktq. =A0A spring keeps the ISV closed when unpowered. =A0Do=
es
>the
> >solenoid help to keep the valve closed when powered or does it help to
>keep
> >it open (I know it varies in a range)? =A0I assumed the valve stays clos=
ed
>by
> >itself since I've heard of people disconnecting it and having an
>acceptable
> >idle when warm.
> >
> >Thanks,
> >Chris
> >
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