Re: 88 MB Urq questions

[Robert Houk - WorkGroup Server Firmware <Robert.Houk@East.Sun.COM>]

   > > The problem is - these duty cycle values are calculated, not derived
   > > from tables (as with ignition and boost values).  The code is complex
   ...
   > It seems that it turns into a MAP system once the air flow meter
   > tops out.  Given MAP (manifold pressure), RPM, intake air temperature
   ...
   > As for the US MC engine, it forgets about the O2 sensor pretty much
   > as soon as you go on boost and uses one of two RPM based duty cycle tables
   > for the frequency valve... (one table for low boost, one for
   > not so low boost levels).  There is no carry forword of anything learnt
   > by the O2 sensor to on-boost behavior.

My understanding is that the primary reason it goes open loop at high
boost (my hands-on experience is limited to the UrQ/MAC-02, where it
only goes open-loop on high boost, no RPM dependency) is that it wants
to deliberately run *rich*. I don't *think* it has anything to do with
running out of sensor range. It cannot do this using the O2 sensor, so
it just starts blasting (well, perhaps a better word would be "dumping")
fuel at power/openloop time.

It should be a simple (for varying -- and not necessarily trivial --
values of "simple") matter to empirically determine new/enhanced
openloop values by very *carefully* seeing when it starts running
non-rich (as distinct from "lean") and using that as your baseline
openloop/enrichment level.

					-RDH