Re: 88 MB Urq questions

[Orin Eman <orin@wolfenet.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.

That's my understanding too.  I've never bothered to measure the
CIS potentiometer voltage vs MAP&RPM.  My dataaq board has an input
for the CIS pot, I just never bothered to connect it.  Scott might have
done this...

Orin.