Re: Strategy difference auto / man

["Bruce Plecan" <nacelp@bright.net>]

IAC's primary finction is life is idle speed.
However it does have some areas where it used for emissions,
and driveablility.
On emisions, without it a sudden snap of the gas in neutral, and as the rpm
fall the engine can stall due too excessive richenss, and to get the AE to
TPS / MAP would be really critical without it.  Also, for coasting, it can
hold the *suggested* rpm a little high, so that during DFCO the motor goes
really lean, and they can balance emissions out during overrun manuevers.
  Then for drivability, it cracks oen realy quick and then as you assume a
cruse throtle setting it runs back in some.  Just tends to give things a
responsive edge, as far as what the driver *feels*.
  Now all of this changes somewhat from cal to cal.
  For what you have planned, I think just setting the commanded idle rpm
low, and the setting the idle speed screw to where you want it will be fine.
Course be nicest to have a hac to see all of what there is for what you want
to do, and render possibly more of it's functions off.
Bruce




> >Yes, the IAC is handled differently
> Could you or Shannen give this ecm neophyte a hint and rough
> explanation of how/in what way the IAC is managed differently, and the
> rational behind it? Or is it simply the difference in idle rpm you'd
> expect between the two? Just wondering if there's something more
> complicated than mere idle rpm.
> TIA,
> Gar

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