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

[Jason Haines]

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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