Clicking on one of the below links will result in a ZIP file being downloaded to your system. The ZIP file should contain 3 files: A virgin copy of the Base eprom used in this hac, a modified copy of that same image with only the datalogging feature added to the image, and finally a text (.txt) file explaining how to hookup the WB to the ECM in that hac and what the hac is doing..
If you download and use one of my hacs, I'd appreciate you dropping me an email with your email address, in case I need to notify users of any updates or (forbid) any bugs.. My email address is just davis@ this site that you're viewing.
All of these hacs should datalog the WBs AFR directly into the "Commanded AFR" ALDL cell, so that any scan tool/package can read it without modification or post-processing.
John <32V_DOHC> from thirdgen.org message boards
Dave Zug
Robert Rauscher from gmecm list
Mark Romans
Greg Westphal
Ludis Langens' wonderful ECM info source
Tim Siford
A/D lookup routine location
2-D lookup table routine location
3 free RAM locations (2 sequential)
1 unused I/O pin on the ECM (0-5V A/D)
About 100 bytes of empty or removable code space in the PROM
So having access to a commented disassembly and ECM schematic
is very helpful..
Diacom(tm) graph of calibration testing
Excel Graph of calibration testing using Craig Moates' software and AKM cable
Here's a short graph of the ALDL RPM and ALDL commanded AFR using my
hac during a startup, idle, and drop into gear. This was an actual test
using the DIY-WB sensor kit as input to the ECM.
AFRvsRPM ALDL graph
    $8D - AUJP ('92 TPI 350 w/A4)
    $8D - AXXC ('92 TPI 305 w/M5)
    $6E - ARAP ('89 TPI 350 w/A4)
    $6E - APYP ('89 TPI 350 {vette} w/M6)