Converting a Motronic ECU Box to Megasquirt

From $1

1. PART 1. Gutting the box
1. 1.1.

PART 1. Gutting the box

1. Find yourself an old ECU box. Any model will do, so long as it has the 55pin connector on it. You can find these on Ebay, or at your local scrap yard. Common in BMW's E30, E34, E32.
2. Dismantle the case. Remove all screws from the underside. Cut any plastic clips off. The lid is held down with metal tabs. Carefully lever these up. If they look as if they have been tampered with before, then it's probably been fitted with an aftermarket chip at some time in it's life. If your lucky, it may be something exotic, and worth removing to sell on ebay! Some Motronic boxes also have a row of screws, covered in red paint. Undo these also.
3. Remove PCB from connector. A bit tricky this. If you have a Dremel cutting wheel, it's much easier. Carefully cut the board as shown, and twist, and snap the board off. Be careful not to damage the connector, or the two screw threads that attach it back to the case.
4. Cut off remaining PCB. Again, a Dremel cutting wheel comes in handy. You can just use strong wire cutters.

5. If your Motronic box has 4 raised bits of metal like this one, then chop the bottom right one off, as I have done here. Again, the Dremel makes light work of that.
6. Drill holes for the Megasquirt board, and any additional components. See template for help. TIP: If you are drilling holes for spark drivers, make sure there are no bit's of stray metal left over. Countersink the holes with a larger drill bit. Failing to do so, may short the driver, and cause no end of troubleshooting (I know from experience!) Click image to enlarge. You may need to save it, and print it from a graphics application such as Gimp. Then set the X & Y resolution to 150 pixels per inch when you print.