Weather Corrections

[Roger Heflin]

On Fri, 20 Nov 1998, Bruce Plecan wrote:

> OK, we have on some applications, Baro, and IAT/MAT.  During
> crank, we can sample for airtemp, and Baro.  As I recall there is
> a formula for working out humidity from that.  Is that "correction"
> used somewhere, in the gm ecms?.  They have some tables for
> baro, and temp, so would it be safe to assume that the humidity
> is worked into the corrections somewhere?.
>   Is there enough change in MAP when changing exhausts that
> the Baro/MAP/Vac correction accounts for change in backpressure?.  Or should
> the EGR flow, be adjusted for that.
> If it should then does the timing/fuel corrections for EGR need to be
> changed ?.
> Thanks
> Bruce
> 
> 

You cannot get humidity from baro and airtemp.  You still need
something to measure humidity, and they don't have any sensor that
would be able to do that, si they would have to ignore humidity in the
corrections.

			Roger