Anyone know why 94-95 LT 1s ECMs have two CPUs

[theKbStockpiler]

I'm into home PCs and study micro controllers and such. I would like to make a DIY fuel injection project but I am unaware of the differences between auto ECM and micro controllers (small embedded systems). I want to run my own code for this. I studied GMs a little and remember that for some reason the 94-95 LT 1s have two CPUs. Does anyone know why. Also if you could steer me to some things to search for I would greatly appreciate it. Like why are files encrypted on auto ECUs. I have googled every search term I can think of to study this and come up empty.

Thanks in advance

[loppad]

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?

[n0dih]

Yes, the older ones were dual CPU/dual memory units. Up to 97 or so IIRC (LT1 and vortec black box).

The files aren't encrypted actually, they are just a hex bin file. HPT encrypts them in the hpt file (I think that is the right one), to keep users from direct access to the .bin and to embed in other data like comments and such. .bin is the universal format for all tuning tools, it isn't in the best interest of HPT or anyone else to allow direct access to it....

I'm into home PCs and study micro controllers and such. I would like to make a DIY fuel injection project but I am unaware of the differences between auto ECM and micro controllers (small embedded systems). I want to run my own code for this. I studied GMs a little and remember that for some reason the 94-95 LT 1s have two CPUs. Does anyone know why. Also if you could steer me to some things to search for I would greatly appreciate it. Like why are files encrypted on auto ECUs. I have googled every search term I can think of to study this and come up empty.

Thanks in advance

[n0dih]

Thanks for posting this, always need this saved. I have the stuff to do, the PCB's are a pain in the toosh to socket, but relatively easy to just pull the old parts off, reflash them on a burner and put back on. The flash parts don't go bad, just corrupted from an incomplete flash, being the way they are programmed this can easily happen with any sort of hiccup, where the newer PCMs are far more tolerant.

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?