Idle screw on NG engine (actually more CIS/ISV now)

[Huw Powell]

>     I think you've still got to adjust the idle screw properly as far as
> getting a correct basic setting is concerned, - i.e. one which approximates
> on its own to a normal idle on a warm engine. Although I'm only familiar
> with ISV systems rather than full blown ECU control, it seems that any
> auxiliary air device that is 'shut at rest' could do little about a
> situation where the basic idle setting is too high and flows *more* air than
> needed.  On the other hand a basic setting that was too low would mean that
> if your stabilization system took a dive for whatever reason you would be
> faced with a non-idling car.

The NG ISV is about 1/4 open at rest.

>      On a well tuned ISV car you should be able to disconnect the ISV plug
> at idle and have the engine dip in revs but keep running.

and an unplugged ISV (or idle switch) results in a higher idle.

There are, however, I believe, some ISV systems where it is closed at
rest.  On those an idle air screw could be a useful way to provide a
"limp idle" mode.  Not that it matters much, you can always use your
right foot to get the car home, right?

--
Huw Powell

http://www.humanspeakers.com/

http://www.humanthoughts.org/