E31 performance chips

I ordered a set of 3 chips from Ebay – $90. Cheap for chips I know, but I assumed it was clearance of old stock as I doubt there is much demand for M70 engine stuff nowadays. In retrospect I suspect this is really a ‘pirate’ set consisting of a copy of eprom data developed by someone else. The set has 3 chips – 2 for DME (engine) and 1 for EML (gearbox).

But anyway.. being a nosy sort first thing I did was to read the chips on my PC as I have an eprom reader for old arcade stuff. I also found a stock ECU chip image floating on the internet, comparing the two revealed clear changes in the ‘map’ area of the chip, and no changes in the ‘program’ area. That’s good as the chip seems ‘legit’! However, problem suspected with the 2nd DME chip – I couldn’t get a consistent read from it – for the technical folks the top data bit seemed to fluctuate (and yes, pins were clean), which changes random bytes in both the program and maps. That’s real dangerous to put in an engine! I am 99.9% sure the seller sent me a bad chip, it’s a good I thing I had the capability to check & verify what was I doing.

Other sites have a good guide to removing the ECUs:



My car has the ’352′ DME which is different from the one mentioned in the links. Here you do NOT need to undo any torx screws – they only hold the pcb to the case, not the case to the lid. (I found this out afterwards of course). You only need to prey apart the metal clips.


But.. why is my DME held together with silver sticky tape!?


Seems a previous owner has been in here before!


And that hardly looks like a factory spec chip!

So seems my car was previously upgraded.. I read these chips too and it’s a different map to stock and the one I was sent.

Difficulty – pretty easy to remove ECU’s and swap chips, but be careful!

(Update : After getting a replacement for the bad chip I ultimately went with the new chips as they ‘felt’ a little better than the old).