93 TBI Caprice - spark, know and AFR data in the ALDL stream

[rr]

The scan tool is required to 'do the math' on the data
stream. For the AFR, just divide the decimal value by
ten. For the SA, multiply the decimal value by 0.352
and add back in the base timing. Sometimes a chart can
be easier for the SA.

I usually pick ALDL stream locations that no math is
done by the scan tool. PromId, INT, BLM, PA3, stuff
like that. That way what you see is what you get.

BobR.


On Thu, 10 May 2001 21:52:29 -0500
 "Jason Haines" <jhaines15 at home.com> wrote:
> I am working on a 1993 5.7L TBI Caprice police car and
> the ALDL data doesn't
> include the spark information (spark advance value or
> amount of retard) or
> the commanded AFR. I tried changing the RAM address
> pointers in the ALDL
> data stream area of the PROM so that it gave me the spark
> and commanded AFR
> instead of the scan tool ID information. It seemed to
> work in that in the
> scan tool id area of the Tech 1 it now reads some numeric
> information that
> changes as the engine starts and then warms up but I
> can't figure out what
> the conversion is to actually understand the numbers
> being displayed nor do
> the numbers seem to change as often as they should for
> spark and AFR values.
> 
> Any ideas? I was going to see if I could live without one
> of the other
> parameters instead and see how that worked. What converts
> the hexadecimal or
> numeric values into engineering values in the ALDL steam
> - is that done by
> the Tech 1 (or other diagnostic tool)?
> 
> Thanks,
> 
> 
> 
> Jason
> 

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