[XfireZ51]

Originally Posted by tpepmeie

Make no mistake, the AYBK is a very different calibration than AUAH. AUAH was the second release production calibration circa 1989. AYBK was released nearly 4 years later and, like all the service cals, is substantially different. Mind you, I am not suggesting its better, or even noticeable, but it is different. Here are some of the changes:

• change to Hot Restart spark retard
• slight changes to low-load / idle spark advance
• less MAT-based spark retard
• new idle speed spark corrections (added correction for low idle speed)
• more DFCO spark retard
• tweaks to startup spark advance (and decay) values
• ESC knock retard entry thresholds reduced
• Added low octane spark retard logic
• some new canister purge / integrator reset values
• CARS (CAGS) barometric pressure criteria added
• shift light disabled via temp threshold
• Baro pressure read/update logic added. And a host of BARO checks to various functions in the program
• minor tweak to crank fuel pulse width
• less open loop MAP enrichment
• various startup enrichment parameters changed
• added new startup enrichment vs. MAT
• Totally re-written / new Closed Loop fueling logic
• warm restart fueling adjustment added
• DFCO enable tps v. RPM added
• vastly different Accel Enrich strategy (was TPS-based, now both TPS & MAP-based)
• speed-based throttle follower offset added
• various tweaks to better control IAC
• new IAC keep alive memory function added
• new IAC control added when in DFCO
• new fuel trim factor vs. Baro pressure added
• slight fuel table (VE) changes

Whew! That about does it. It (along with the other "service" issue calibrations) are just simply a little more refined, complicated than the original issue ones. Not saying its better or worse. Engineers tweak anything when given enough time, and over 4 years they just got more sophisticated in the LT5 calibration approach.

Hope this helps.
Todd

Todd,

Would you indicate which of these are calibration mods as opposed to added /modded routines? I noticed that you show AE logic using both TPS and MAP. Are these tables? Is this unique to the AYBK or did it show up in a earlier def?