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gazz200581
04-22-2006, 02:26 PM
I'm looking into chipping thr ecu on my 1990 520i and have been told I need to check the number on it to find out which one is needed. Does anyone know where this number is and where the ecu is!
cschollum
04-22-2006, 02:40 PM
I'm looking into chipping thr ecu on my 1990 520i and have been told I need to check the number on it to find out which one is needed. Does anyone know where this number is and where the ecu is!

The ecu is located in the rear of the engine bay on the drivers side (RHD models) you need to remove the top black cover, big phillips cross head screwsriver 4 screws. In here you will find the ECU, unbolt it and un plug it and on the top is written a number. the euc is usually the nearest to the windscreen in that box

Id have to question though the difference you would feel in a 520 and the state of the engine after 210,000 miles - depends on its maintenence history i guess
ThoreauHD
04-22-2006, 03:07 PM
It is the box closest to the firewall/windshield. Also, mine had brass metallic clips on either side that were fun to rip off with pliers. And had to remove the adjacent wiring block to move the ECU out of position enough to pull it out. Yours is a 90 model, so I'm not sure if you will have the same encumbrance.

I also don't know the gains you can get from a 2 liter of that age, but I guess something is better than nothing. Make sure your engine is in top shape before you pop it in. Don't want any ignition coil, spark plug, head gasket leak crap going on when the thing rev's higher.
NAT9566
07-23-2006, 11:53 PM
yes thats where it is....
so how much power can i expect to gain in attempting to put a mod ecu for my m20b20 engine?.... will putting a m20b25 head do much for power?....... heck is getting a new short engine better?...
SC David
07-24-2006, 12:44 AM
It's not a car built to be too fast, so don't expect much. I chipped my M20B25 with slightly noticeable gains, but I'm not sure it's entirely worth the money. I'm thinking about putting the Jim Conforti chip in to replace the BavAuto one I have now...maybe it will have better results.