Programming 101

[Bruce Plecan]

Again, this material is for educational purposes, and relative to the
programming 101 series of articles.  If you have missed any of the
101 series please search the archives, and read every mention of 101.
  This is the math behind what is at the locations I've explained so far.
Now you can be dangerous to your engine.  Please remember make
small changes, and check often what is going on inside your engine.
ie. plug cuts, and plug readings.  The is some material about tune-ups
at 332 incoming, and if you have limited experience or an old pro
if you have any questions, ASK them.  As an extra bonus, some 
stuff that doesn't apply to the 747 is included....  

Temps
     data byte * 191/255 - 40 (degrees C)

Speeds
     0-255MPH

Revlimiters
     P4  - 983600/double data byte
     C3  - 25 * data byte      (1227747 is a C-3)

Idle RPM's
     single byte * 12.5 (0-3187) or     (This is more common)
     single byte * 25 (0-6375)

WOT AFR (percent change)
      100 * data byte / 256      (This give 0-100%)

PE
     data byte / 10 or        (absolute AFR)
     (data byte - 128) / 128 * 100 ;   (This gives -100 to 100%)

Fuel Shut off
     0-255MPH

Checksum
     Add all bytes from CS start (usually start right after EXP byte)
through the    last byte. If sum is over FFFFh (65535),  let it roll over
and take only last   two bytes. For example, if the sum of all bytes is
72,182 (0119F6h), drop the  01 at the start. You get 19F6h as the Checksum.

Cooling Fans
     Temps are data byte * (191/255) - 40 (degrees C)
     MPH are 0-255

VE

      data byte/ 256 * 100)     (This gives 0-100%)

TPS Percent
      data byte/ 255  * 100     (This gives 0-100%)

Knock Retard
      data byte * 45/ 256      (This gives 0-45 degrees)

Knock Attach in mS
      data byte *  .0225

Knock Recovery in mS
      data byte *  500 / 256

Spark Advance
      data byte *  90/256);     (This give 0-90 degress)

Final AFR from PE, WOT AFR and Injector Base

   6553.6 * (PE rpm + PE temp +128)/256 * Injector constant

Cheers
Bruce