Programming 101

[Bruce Plecan]

Again, please read all past postings in reference to Programming
101.  (as written this current ecm is the gm 1227747).
Again this is for educational purposes. Performing table modifications as
mentioned herein may violate local/state/federal laws if done to a vehicle.
Any ecm table/code modifications can
do damage to an engine.  Do not attempt these modifications
unless under adult supervision.  I have no formal electronics training
and this information seems to be true to me.  If you find fault with
any of this please e-mail me, (my address is nacelp at bright.net) so I might
be able to research, and correct any errors that I make.  When quoting this
article, please edit your reply (of this material).

  Today's two tables are both coolant temp dependent ones.
One being for cranking fuel, which is at 044A-0458, and idle fuel
vs temp at 05F5-0605.
  Now that they have been posted in the 332 incoming area for
about a week I'd think everyone has gotten a copy of GMER,
and delco edit.  If you haven't then this is the time to.  Looking
at gmer will give you a sense of exactly what tables look like,
and how they vary, and getting delco edit will let ya see what
they look like in prom form, ie hex editor.  As I mentioned before
some of the tables are preceeded by offsets so just before a
large table you might see a group of entries like   00  40  0F.
That would correspond to a 0 rpm offset, an 40 MAP related
offset, and a table with a column width of 15 entries.  So now,
you can look at a dissassemblied prom file like at ludis's site,
and compare that to what tables look like in an editor, and
use delco edit.  There now you have all the basics for looking
at tables, finding tables, and editing tables.  If you search the
archives for Tables, Maps, tuneup, you then have the info for
how to monitor changes ya make, and what approximate values to
change how much.   Granted we still need to discuss some more math, but at
least now, everyone can get up to speed on where
to at least start to look for a table.  What tables look like in a
proper editor, and how to take a raw hex file, and manipulate
it into an orangized file,  and included in delco edit is a hex to
dec conversion, and also a factor conversion so if you want to
make the *90/255, you would just hit F and then .352 and all of
the file or your table would be expressed in degrees.
  If anyone has any tables, locations or anything they would like to
share in ref to any gm ecm, I'd invite them to post it to the list,
or write me, with that information.
  Again I would like to thank those who have contributed to making
this possible, and again say that I did not discover any of this
but rather am reporting it, as I understand things.
  If you are having trouble understanding any or all of this your
probably not alone, so write me, and I'll try to better explain these
matters.
  HTH
Bruce