just wanted wanted to share my experience of chipping a mines ECU.
everywhere I read, people were saying that the mines ECUs were covered in an impenetrable epoxy that made them impossible to modify or read. So i took the challenge and decided to give it a go. My verdict is that the plastic coating they use to cover the EPROM is fuel and solvent resistant. even MEK(PVC pipe primer, aircraft remover, paint stripper) didnt affect it at all. So next i tried heat. Bingo, it needs quite a bit of heat but not too much or you will fry the logic module right next to the EPROM. I used a hot air station with a 10mm tip at low air and 300C. Using a box cutter blade, I like to use one of those stiff trapezoidal ones, I blew hot air onto the goo and pushed down lightly with the blade until i hit the pcb, pulled back a little then levered the goo up. it peeled away from the conformal coating and was quite pliable. I went around the edges slowly trying to get as much off of the sides of the EPROM as i could reasonable manage.
Then I went and got my solder sucker, residue free liquid flux and temperature controlled iron. I set the iron to 220C and went to work. it took about 3 passes for each pin to free it completely. afterwards there were about three pins still stuck so i used a bolt to wiggle the pin and act as a heatsink, I melted the solder then wiggled the pin in its hole so it would form a cold solder joint, freeing it from the bond. once all pins were tested by pushing on them with the bolt to make sure they were free, I wedged the tip of the blade between the EPROM and the PCB, gently wiggling it under as I heated all sides of the EPROM and usws it as a lever to pull up the chip. how much force exactly I used im not sure but I aimed for just a slight amount of deflection in the blade. maybe 4mm across an inch in what seems like 0.6mm flat steel. the pins came through nicely and i didnt tear any vias or scratch anything too badly.
In order to see how much damage I had potentially done, I plugged the HN27C256HG-85 into my EPROM programmer and got a perfect read! it seems to load fine in Nistune and I verified the read a few times, reinstering the chip into the zif to make sure all the pins were connected properly and I wasnt getting any bad data from a bad connection.
www-dot-megafileupload-dot-com/kklN/1-dot-bin
this is a mines ECU rom binary for the 23710-41P11 TT AUTO
those scratches under the rom are from where i pried it up. I'm a bit disappointed by the scratch through to bare copper on the ground plane but those other scratches that may seem to be cutting fine traces are just marks in the conformal coating. I tested the traces for continuity on test points and they were all perfectly fine with no continuity where the scratches are indicating that the mask is still intact, doing its job, protecting the traces.
I didnt have any chip sockets around but I had a bunch of machine pin rows so I used those.
