Turbo 2.8 - Part 2 - Engine Management.
Alright, so we now have a brief overview of what I intend to do, so lets get to some of the specifics of my engine management. I was lucky enough to have the "6869" ecm in my 86 SE, as they apparently only came in the 85 and possibly the 84 V6 cars. This particular ECM has an input for a knock sensor and the ability to control an electronic wastegate.
I thought about hooking up a knock sensor, but I don't think I will at this time.. If you are looking to do this, you'll need to enable the code in the ecm and purchase an ESC module and knock sensor. The archieves have some more info on this.
So, the ECM is the brains of the whole engine's operations. The EPROM contains the specific instructions for the engines everyday life. This must be heavily modified in order to work correctly with boost, but don't let that scare you, it's really not too bad. We'll get more into programming and tuning in Part 3 - Chips and ECU's.
The stock EPROM (2732 chip) can "theoretically" be erased and reprogrammed, but I've heard that it is hard to do and sometimes doesn't work. An EPROM must be erased using UV rays, from a UV eraser. You can purchase EPROMs to do this to, but I thought it would be a PITA to have to erase a chip with the UV eraser every time I wanted to burn a new chip, so I decided to go with an EEPROM.
An EEPROM can be electronically erased with the same hardware you would use to program it, so it basically makes life a LOT easier. I'm not really using an EEPROM I guess, because I do not have to erase it before I program it. The ATMEL AT29C256 EPROM can be written over and does not require an erase to have new data burned onto it, but requires a special adapter from www.moates.net. Craig is the champ for sure, shipping is fast too.
What you'll want:
$30 - G2 - 0.60 Memory adapter
$07 - S4 - Low prof ZIF
$12 - C1 - 2 29C256 EPROMS
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$49 bucks, plus shipping.
We'll get to the programming hardware and software in part 3, no worries.
I will cover the mods to my ECM in this post. It wasn't too hard, but if you've never used a soldering iron before, you may not want to attempt this.
First, you need to remove the ECM from the car. It is located under the console, on the firewall. Loosen the 4 nuts that hold it to the plastic brackets, and unplug the 2 wiring harness connectors. Bring it somewhere warm and take all the bolts out.. 4 from the top, 1 from each corner on the sides, and a small one between/above the 2 connectors for the wiring harness. Carefully pry it apart and you'll see this.. (well, not quite, I had already removed the old EPROM, you can see the empty EPROM socket)
Next thing you need to do, is to pry the plastic socket from the pins, so that you can extract each pin seperatly. NOTE: Be VERY carefull at this stage, I lifted 2 traces by accident and had to repair them.. /sigh..
Now, you see where the black socket used to be, there are just pins now.
Get your iron hot and grab a pair of needle nose pliers. Grab each pin with the pliers and pull up gently while heading the base of the pin with the iron, they should pull out easily.
Now you have to get the solder out of the holes so you can put in the socket. You can either use a solder sucker, or desolder wick. This will require you to take out the 2 bolts in the corners to give you access to the bottom of the circuit board.
After that, drop the first socket into the holes and solder all the pins from the underside of the board.
At this point, it is a good idea to take your original EEPROM out of it's plastic carrier (that fits into the socket we just removed) and pop it into the new socket. Go hook it up in the car and make sure it still works.. If there is anything wrong, the check engine light will come on immediatly and it will work like crap.
Take a moment and look at the above image, notice that there is a small notch on the right hand side of the new socket. Just to the right of that, you can see a black arrow that I drew on the board so that I new the correct orientation of the original EPROM. This is CRITICAL!!! You're original EPROM will have a notch at one end as well, ALWAYS match them up.
Next, I took the original EPROM out, because my test was successful, and I put the adapter in. If you notice, the adapter hangs over on one end, make sure that this overlap is on the same side as the notch. I then inserted the ZIF socket (not needed, but makes pulling and replacing the chip a breeze) with the release handle in the same direction of the notch.. Then, finally the 29C256 chip, with the notch facing the ZIF release handle. Programming of the 29C256 chip will be covered in part 3 don't forget.. 
With the case re-installed, but the inspection cover off, this is how far it sticks out.
Once the tuning is done, you can remove the ZIF socket and put the 29C256 chip directly onto the adapter and will probably only have to modify the inspection cover a little bit..
I put a nice little window behind my console so that I can get the chip out of the car in under 5 seconds, reprogram in about 10 seconds, then reinstall in 5 seconds.. Very very handy.. I may make a little plate to cover the hole, but probably not..
Craig has a set of instructions for installing this as well, I feel his are better than mine, so please check his as well..
http://moates.net/gmecm/g2/g2instr.htm
Vist the other parts of this series.
Turbo 2.8 - Part 1 - Design and Parts.
Turbo 2.8 - Part 2 - Engine Management.
Cheers,
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Andrew MacPherson
86 2M6 - Turbo what?
82 Z28 - www.ttz28.com
96 CRAPalier - Beater
[This message has been edited by Mac (edited 01-24-2004).]
