What is this for?

[Huw Powell]

> I got my hands on a Bently for my Audi 4000S.

excellent, congratulations...

> Anyways, I was doing the CONTROL UNITC continuity
> check as per say in the book.  Well, I've found out
> that my throttle switch doesn't work.
> Continuity test results:
> Open when no throttle -> good.
> Open with throttle ->bad, supposed to be short.

the throttle has to be open far enough to press the switch - I'm sure
you got that right though...

> What does the throttle switch do?  I haven't replaced
> it yet.  But, my car seems to work great without it.
> So that is why I am writing this message, what's it
> for?
>
> Similarly, what is the purpose of the idle switch?

WOT switch make the car go into open loop at an enriched fuel setting.

idle switch tells the computer to use the ISV to regulate the idle; it
also cuts off the fuel briefly when actuated, in fact it kills the fuel
if the revs are over 1400 or so rpms (which they aren't for long if your
foot is off the throttle, but try driving with a bad, always closed idle
switch!)

The two come as a single unit, of course, with one connector, and run
about $70 last time I checked (new one on the coupe last spring...)

The idle switch is tough to mount, as it is on the bottom of the
throttle body and has to be adjusted slightly to be in the right
position.  At least the throttle body is easy to pull once you get those
old bolts turning, and the gasket to the IM is cheap.

--
Huw Powell

http://www.humanspeakers.com/audi/

http://www.humanthoughts.org/