High idle after start

[Gregory A. Parmer]

> > > >> When I initally start the thing the rpm goes to over 1500 for 15 to 20 >
> > > seconds then settles back to idle...
> > > >
> > It has to do with how fast idle on a cold engine is implemented.  In the
> > 1227170 ECM, and probably others, the IAC is simply opened another _x_
> > counts from the learned warm idle position.  The ECM does not try for a
> > specific fast idle rpm.  (Surprise!)  I think the '7747 is the same
> 
> > If the learned idle IAC position is too low, then the increase for fast
> > idle is a much bigger percent change than it was meant to be.
> > Similarly, if the learned position is too high, the increase won't be
> > enough.  This is why the IAC position for idle is important.

How timely!  I fired up my '7747 controlled hodge-podge of
parts last night.  The manifold is a Cross Fire Injection
unit with 2 IACs--twice as fast on high idle after start.
One of 'em may get unplugged until I get a chance to program
that out.

As I understand it, the IAC expects to be running in a
certain range of steps. If the throttle is too closed
then too many steps of IAC are required and if it's too
open then IAC may close completely trying to maintain
the pre-set idle RPM. True?

There must be a tune-up manual somewhere that describes
this, but I ain't got it. Can someone describe what
values we should be shooting for on IAC...like what
would be normal for the '91 PU. I'll document as
I go.   Lord knows progress is slow enough.

For starters...tranny in N and warm engine,
1) key on, engine off       (prep for start) = ??
2) key on, engine idling         (warm idle) = ??
3) key on, engine off idle         (dashpot) = ??

Discussion has been of "2)".
So far the consensus has been that an IAC cnt of 25 is
normal for idle and that Jason's "9" is too low
and that's the cause of the high idle. Guess what 
fellers...mine's "71" and exhibits EXACTLY the
same behavior.  SNAFU may be a bit too critical, but
it does appear normal...as if GENE needs encouragement. :)

My values are abnormally high because I set idle to 1000
RPM for initial tuning. Nevertheless, I've got
1)=~145, 2)=71, 3)=~91
Telling me that my throttle blades need to be opened a bit
and that my preset idle RPM needs to be dropped. No?

-greg