RE: 7749 guru needed....

["Jim Sloan" <leroy@sunflower.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?

As I understand it, the F1 (main spark advance), F77 (base boost multiplier)
and F29 (base pulse VE v. RPM and MAP) tables can control timing and fueling
up to 3 bar (with the 3 bar MAP sensor).  The far right column will be 3 bar
(around 29 psi).  The values for the other columns can be calculated from
there.

Then again, maybe I'm confused....heheheh

Jim Sloan
leroy@sunflower.com
Syclone VIN# 1206
http://www.sunflower.com/~leroy
Lawrence, Kansas




>
> 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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