Re: 7749 guru needed....

[Ludis Langens <ludis@cruzers.com>]

Barry Tisdale wrote:
> 
> If the two bar setting is
> selected in the chip and a 3 bar MAP sensor used, an ADC count of 127 then
> becomes around 7.5PSI manifold pressure.  Then, per the 20-100kPa 'VE vs
> RPM' table(s), atmo pressure falls somewhere around 70 kPa, and this table
> will then also control fueling up to the 7.5 psi level.

Ummm, it sounds like you are using a 3-bar sensor without the software
patch to enable use of a 3-bar sensor!

The patch ought to do the following:
  1) An  ASLD  instruction (aka "times two") in the fuel code needs to
     be changed to do a "times three" instead.
  2) Several parts of the function at $F4F0 need to be changed.  This
     function computes the "fake" 1 bar MAP.  It also calculates the
     1-bar and 2-bar table indices.  Finally it adjusts the MAP value
     to a true absolute reading (sensor 0 does not equal hard vacuum,
     the SpeedDensity formula needs a value where that is true.)
  3) There is likely an initilization code fragment that duplicates a
     small portion of the $F4F0 function.  This fragment also needs to
     be changed.

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/
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