More silly ideas

[Tom Sharpe]

I thought some ECUs measured baro once at key on and remembered it--- not good for
weather changes or long drives or climbing mountains... another .02  TomS

Ludis Langens wrote:

> Bruce Plecan wrote:
> >
> > What if someone wanted to use a straight full time baro correction (for a
> > MAP system)?.   Could it be done as simply as using a 1bar MAP referenced to
> > atmosphere, and then the output from that one used as the reference voltage
> > to a second MAP that is referenced to the engine vacuum.
> >    Then carrying this further how about as a correction for 2+3 bar MAPs?.
> > All of the above would be require deleting the baro calc from the prom, and
> > recalibrating the Tables, that are VE related.
>
> I'm not sure quite what you are trying to do.  I assume you want to get
> rid of the inferred BAP calculation and to substitute a real BAP sensor.
>  A MAP sensor measuring open air, hooked to another ECM analog input,
> and with some code changes would work.
>
> If that's not what you want, keep in mind that the ECM computes and uses
> various pressure values.  It has absolute pressure, baro pressure, and
> gauge pressure (aka manifold vaccuum).  For example, one ECM has an
> intake VE table indexed by MAP, and an exhaust VE (aka backpressure)
> table indexed by BAP.  The same ECM also has lots of tables indexed by vacuum.
>
> --
> Ludis Langens                               ludis (at) cruzers (dot) com
> Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/