My car is a 1991 Firebird 305 L03 Auto 2.73 gears.

Been trying to get a start on this chip tuning thing.
1228746 on a $61 so downloaded an AXKT1113 bin from gmpcm site (is it just me or has this site been down for a while) made a few mods - removed speed limiter, added a few degrees ignition advance etc
When i removed the ecu from car and finally got the old chip out from the stupid black plastic holder it has a BCC code ANTS ANTS 8022 on a silver label on the chip.

Q - Is there a big difference between these 2 bin files and does anyone have a link to an ANTS8022

 

AXKT is an auto fed emissions calibration.
ANTS is an auto cali emissions calibration.
If you have a cali car then it got the ANTS from the factory.
The earlier L03's got the AN__ chips and the later like in 91 and 92 got the AX__ chips. At least that's what I've dug up. The ANTT is probably the most popular auto chip to start with in an L03 application. The ANLU would be the starting point for a L05.
The differences of the AXKT and ANTS are as follows:
Obviously there is a difference so the checksum is different. Then the prom id is different because again, different eproms. The main spark table is all different. Same with Coolant comp SA vs Vacuum. The Map mult for trans SA vs s/d map cnts is slightly different as well. It doesn't stop there. EGR qualifications coolant threshold is different, map thresholds different too. Closed loop coolant thresholds are different. Idle afr vs vacumm, used instead of afr vs vacuum is different but only slightly so, almost no difference. Closed loop decel enlean map threshold (low value) is different. The hard fuel cut mph speeds are different. Main vol eff table has only 1 or 2 cells different so again, nothing obviously noticable. Open loop AFR vs Vacuum table has differences. The "Mean rich/lean threshold for unfiltered o2 as a function of air flow" and "Rich o2 threshold as function of air flow" and "Lean o2 threshold as function of air flow" are all different. "Proporthinal value vs slow o2 error" , Error 43 param (ESC error) are slightly different.
Max throttle follower steps is different. The difference is opposite of what I would have thought. I figured that the more TF steps you had the lower the emissions from snapping the throttle closed but from the calibrations it is the cali (ANTS) that has fewer TF steps allowed than the fed chip! What's that about? In my calibration my TF steps are limited to less than both but that's a personal preference of having the car idle down and not overpower my crappy brakes .
Then the rest of the code that is stored in the eprom looks to be VERY similar with only minor differences and lots of data shifts where some code is moved around because other code is shorter. It's hard to explain because I don't even really understand why or how but it would be interesting to figure out why they did the code changes between the calibrations.

 

Rename the attached file from bins.bmp to bins.zip . Included are a bunch of bins from all applications of the 8746 ecm. Don't bother with the caprice files. In the zip is a html file that has the description of each bin's application.

 

Thank You......again.