Need help undertanding my confusion!!

[ADEN]

Bmw m20b20 1989 bought it year ago running ok but not perfect i happened to hear about performance chip and i contacted a dealer and he asked me about ecu p/n i opened mine and it is a 173 so he provided me with a chip and i see very little improvement or just no improvment so i put back the stock one, after a while i discovered that ecu 173 is for m20b25, so the guy gave me a m20b25 chip!!!!

Will i gain any improvment if i got 172 ecu or just stick with the 173?

Is the performance m20b25 chip should help with my m20b20 or will just create performance loss or less mpg?

Note: Bigger injectors are found installed (the green ones).

Do think that justify my rich condition?

Sorry for the confusion i caused and my poor English.

[roguetoaster]

There's a large power difference between the B20 and B25, so the fuel tables are probably going to be different. I suspect that you will actually gain power by returning to the B20 DME. You are probably going to be okay keeping B25 injectors.

[ADEN]

There's a large power difference between the B20 and B25, so the fuel tables are probably going to be different. I suspect that you will actually gain power by returning to the B20 DME. You are probably going to be okay keeping B25 injectors.

Thanks man, now my low mpg justfied and having power only after 5k rpm.

[ADEN]

While i was googling i found the 172 and 173 can be used for both m20b20 and m20b25, is that correct?

https://www.e30zone.net/e30wiki/index.php/Motronic

[roguetoaster]

Cannot say specifically, perhaps the difference between the two is just in the EPROM. If that were the case you'd need to see if you could verify what your original EPROM was.

Alternately, it could be that the B20 is just not an exciting engine, at least the one I had wasn't, at least compared to a B25.

[ADEN]

Cannot say specifically, perhaps the difference between the two is just in the EPROM. If that were the case you'd need to see if you could verify what your original EPROM was.

Alternately, it could be that the B20 is just not an exciting engine, at least the one I had wasn't, at least compared to a B25.

I know it is boring but i put heaps of parts in it, my best luck here is to find a whole e34 with used b25 that needs parts and work and duo to b25 not popular here b25 part are hard to source