Once I had a problem programming a 94 Camaro: I used a wrong version of the tuning software so the flash memories went corrupted and the car didn't start. I found this post from a forum (camaroholic.com) that now is gone by the way:
"From: Camaroholic
YaBB Moderator
PCM Repair - how I do it
01/24/07 at 12:17:41
1) Make sure the PCM is dead. What I do is to completely disconnect the PCM (removing all power), and then reconnect it. Then I'll run PCMread (from
http://carputing.tripod.com/pcmread.exe {right-click save-as} Carputing's web site, free download). I select "Display Comm Data" from the Setup... Comms menu. I then have everything hooked up, and hit "Action... Connect". If the PCM starts reading and doesn't stop, it's fine. If the PCM starts reading and then halts, you need to replace the E-side chip. If the PCM sits there and does nothing, you need to replace the T-side chip.
2)The Blue/Gray board is the "T" side. The Red/Black board is the "E" side. These stand for Timer and Event (not Transmission and Engine). I keep binaries available for public download at:
http://www.akmcables.com/Obd1-t.bin
http://www.akmcables.com/Obd1-e.bin
or for OBDII people:
http://www.akmcables.com/Obd2-t.bin
http://www.akmcables.com/Obd2-e.bin
I do NOT know what those files are (auto, manual, year, gears, etc). They are just files to be used to get the PCM back up and talking. Do not try to run your car on those files! I extracted those files 7+ years ago and have been using them ever since. LOL.
3) Remove the appropriate chip, clean it with desoldering braid, insert it in to the programmer, erase it, and then program it with the respective file above. Then solder (or socket) it back to the circuit board.
4) Reflash the PCM with your good file. Done!
If you do not have an EPROM programmer, you can use an Intel Pro 100 Ethernet Adapter (on ebay for under 10 bucks) as a programmer. I will have a thread in this forum to cover that.
If you hose the chip (it won't take a program, etc), I do have spares. They can be easily hosed with static electricity or excessive heat."
I finally took the PCM to Ion (
www.madtuner.com) and he fixed.
There are some projects trying to build a general pourpose ECM from scratch and most are taking as a base GM's OBD1 ECMc (like the "730" as fas as I remember) and adapting it to their needs:
http://www.diy-efi.org/diy_efi/
http://www.code59.org/
Since OBD1 ECUs are EPROM and EEPROM based systems you'll probably will need tools from this sites:
http://www.moates.net/
http://www.tunerpro.net/
http://www.tunercat.com/
Which microcontrollers are you interesting in?