Air Flow Measurement

[kleenair at ix.netcom.com]

tom cloud wrote:
> 
>         [ snip ]
> 
> >>Sure seems a lot better than using MAP and some magical 'volmetric
> >>efficiency'.
> >
> >I'd prefer to use MAP and learn (and adapt) the VE function using closed
> >loop A/F control if I didn't need EGR (and lots of it - I'm working on a
> >DISC engine project).
> 
>         [ snip ]
> 
> >Andrew Rabbitt
> 
> I think tha's what I've been trying to say .... thanks.  Now, when
> you say 'closed loop A/F' do you mean EGO?  And how would you 'learn'
> off-stoich conditions (esp. power / rich  and economy / lean), since
> the EGO feedback isn't really 'calibrated' at that point (I've assumed
> that it would still give useful, if not perfect, data).
> 
> Tom Cloud <cloud at peaches.ph.utexas.edu>

Hi Tom,

That's a good question and here is an explanation that is somewhat 
related:
Adaptive learn is normally used for two purposes:  1- to correct for 
varrying fuel composition, and 2- to account for changes in engine fuel 
requirements (i.e. air flow characteristic changes).
The adaptive learn cells are generally larger than the normal VE table 
cells.  Each cell is supposed to cover an "engine operating region" as 
opposed to a specific operating point.  So, it's possible to approximate 
the correction factor for fueling at WOT, by using the adaptive learn 
correction factor at a slightly lower throttle angle that still operated 
in the closed loop mode.  Its an approximation at best, but its better 
than no correction, especially if you consider changes in fuel 
composition (i.e. going from regular to oxygenated fuel, etc.)

Best Regards,
Mazda Ebrahimi