Changing ECU from 0 261 200 027 ---> 0 261 200 021

[elemental]

I have an 85e that has the stock ECU # 0 261 200 027, I have a freind that has a Authority Performance Engineering Chip in a 0 261 200 021 ECU for a 84e Could I change the whole ECU with out any prolbrems? As far as I have found the difference is the 027 has a detachable chip, is that they only differance,? Thanks

[BS87]

Uhhh, going from 027 to 021 would be a downgrade............ and how did your friend manage to get a chip in the 021, which does not have a removeable chip?

[elemental]

Not sure what the lineage is on it, Even when the ecu's chip cant be replaced you used to be able to send it in for reprograming, and a downgrade cus the chip isnt interchangeable, I wouldnt think there were any mods the the ECU other than that same program I would imagine,

[BS87]

Still, most people who have the 021 upgrade to the 027, so i have no idea why you would want to do the reverse

[elemental]

To get a remaped ECU for free

[rs4pro3]

You can hand solder a chip into the 021 A couple of my friends with 325e did this one managed to fry the circuit board(not good with soldering) and the other worked fine. They were custom burned chips.