320i and 325i ECU's.

[Sanchez]

I have a chipped 325i ECU on loan in my 325i e30.

Can I put a 325i chip in a 320i ECU as I have a few 320i ECU's about?

I was also wondering why so many different numbered ECU's. I understand pre-post facelift would differ.

[Sanchez]

Looking at the zone wiki I can use both the 172 and 173 ECU's in both engines.

Other parts of the wiki state 172 is 320i and 173 is 325i.

[Brianmoooore]

173 and 172 are identical, apart from the 'chip' that contains the software. Fit a 325 'chip' to a 172 it becomes a 173.
The reason for more than one ECU number per engine size is advances in electronics during the E30's production run. Note that cost savings might have been the motive, rather than performance enhancements.

[Sanchez]

Thanks Brian, you seam to answer all my questions.

[Speedtouch]

Any of the later Motronic 1.3 six-pot ECUs are interchangeable, i.e. 172/173/179/380/381 - as Brian says, it's just the EPROM chip that differs.

[Sanchez]

Hi Maurice, you saved me a effort looking to pm you.