type44? Fwd: Re: ISV

[Richard van der Hoff]

On Fri, 12 Jul 2002, Chris Dyer wrote:

> Again, my ignorance is playing out here. I know what the ISV is (after
> numerous cleanings...) but what is the idle switch? What's its job? Where is
> it? Who is it dating?

The idle switch is a switch on the throttle which indicates to the ECU
that the driver's foot is off the pedal - and hence, just as Huw says, the
ECU needs to control the idle speed.  If it opens, the ECU decides the
driver now wants to go somewhere and, instead of playing with the ISV and
spark timing to obtain a sensible idle speed, goes for maximum (-ish)
brake torque.

> (my car is a '87 5ktq; does it even have one?)

'spect so.  It hides on the bottom of the throttle body.

Rich

>
>
> >From: Ben Swann <bswann at worldnet.att.net>
> >Reply-To: "bswann at worldnet.att.net" <bswann at worldnet.att.net>
> >To: "'richard at rvanderhoff.org.uk'" <richard at rvanderhoff.org.uk>
> >CC: "'quattro at audifans.com'" <quattro at audifans.com>
> >Subject: Re: ISV
> >Date: Thu, 11 Jul 2002 11:05:53 -0400
> >
> >Just adding 1 thing to what Huw says below.
> >
> >For type 44/5000/200 with 2 wire ISV's, if you can blow through it, it is
> >bad.  Some are worse than others, but if it passes any air -> BAD.
> >
> >Three wire sensors do not adhere to this test.
> >
> >Ben
> >With many too many flaky ISVs to stik a shake at!
> >
> > > > Did you check your ISV with a 9volt or is there another method. WHen I
> > > > checked mine with a 9 volt it clicked. Is it supposed to do something
> >else?
> > >
> > > For what it's worth, I just connected mine up in series with an ammeter
> >to
> > > its connector, and put it where I could see it when I turned the key on
> > > and off.  I didn't have a 9V to hand ... I'd expect it to do more than
> > > click though (like close or open or do something...)
> >
> >The ISV is driven on a "duty cycle" basis.  Some are two wire, some
> >three, some are closed at rest, some partly open.
> >
> >In order to regulate the amount of air they allow through, the ECU sends
> >a constant stream of pulses, so the ISV sort of flips open/shut rapidly
> >- and makes a buzzing sound while doing it.  The width of those pulses
> >determines how much it is "open" versus "shut".
> >
> >For this to happen two things are required: the engine must be running,
> >and the idle switch must be activated.
> >
> >--
> >Huw Powell
> >
> >http://www.humanspeakers.com/
> >
> >http://www.humanthoughts.org/
> >
>
>
>
>
> from chrisdyer at hotmail.com
>
>
> _________________________________________________________________
> Join the world’s largest e-mail service with MSN Hotmail.
> http://www.hotmail.com
>
>
>

--