It's from the FRRAX forums:
For anyone interested in modifying OBDI LT1 PCMs, the price of entry recently went down a bit, since TunerPro definition files are now available for the $DA3 and $EE masks.
For anyone not familiar with this, TunerPro is a freeware editing program written by thirdgenner Mark Mansur. It's available from:
http://www.supportfitness.com/mark/tunerpro/
What makes it work for the LT1 PCMs are the .xdf definition files, available from:
http://www.moates.net/fileman/index.php ... l%20Motors
The $DA3 mask is for the '93 LT1 ECM
The $EE mask covers the '94-'95 LT1 PCMs
Some '94s were a slightly different version, called $EEb, which is available there too. (if you open a bin using $EE and the injector constant doesn't make sense, it's probably $EEb)
TunerPro doesn't flash PCMs (yet), so you'll also need the TunerCat winflash program ($20) to work with the '8051, along with an ALDL cable or benchtop programming harness.
For the '92-'93s, you'd need some type of PROM burner instead.
With either, you'll want some type of scantool to see the results of your work. Freescan and Datamaster are well known. TunerPro RT can also work as a scantool. Previous versions had a little trouble connecting to the LT1 PCM; I haven't tried the latest release to see if that's been fixed yet. If it's not, I'd expect it will be really soon.
So, for a '94-'95, spend $20 for Winflash, build your own cable (~$30), use the free software, and you're in business for a whopping total of about $50. So, if you've been interested in trying PCM programming but didn't want to spend a lot of cash, you have your answer.
Ben