Re: 7749 guru needed....

[Barry Tisdale <btisdale@cybersol.com>]

SyTy (like Fiero??) software has a one bar or two bar MAP sensor option.
Trying to logic this thing thru, I come up with the code 'knowing' what the
MAP is by the MAP A/D converter input.  With a one bar MAP, 100kPa would
correspond to 255 counts on the ADC.  With a two bar MAP, this number
becomes 127 (indicating atmospheric pressure).  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.

Is the atmo ADC reading taken from the MAP sensor @ the instant of ignition
key 'on'?

Is my reasoning on track or seriously flawed?

These mods have been done numerous times in the past w/ SyTys, but folks
seem to have just an 'empirical' knowledge of what works; I'm trying to
determine the "why" as well as the "how" of things.

Thanks - you guys *are* gurus - Barry

At 01:31 AM 04/02/2000 -0800, you wrote:
>If the SyTy code follows the same pattern as the Fiero 1&2 bar code,
>then the VE tables only cover a one bar range.  They are indexed by a
>fake 1 bar sensor value.  Thus the heading of 100 really does mean
>100KPa.  Fuel delivery under boost is controlled by YetAnother table.

>Ludis Langens                    
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