ECU questions...

[Bimmer325e BD]

Hi, so I have a 88 325 superE and my ECU has ending numbers #153 which is the same as the 325i/is/ix's and I talked to BavAuto,Ireland Engineering, and such, they say that I can probably use the performance chip for the ecu that I have(153) and it will provide hp/trqe gains/revlimit by 500. but I talked to Turnermotorsport and he says that I have the wrong ECU for my optimum performance. Supposedly i should have the ecu # 154..anyone know anything about the ecu's and what should i do??

[jmc1590]

The 153 and 154 ECU are both Motronic 1.1 units. The 153 was standard for 2.5 liter 325i's and the 154 was standard for the 2.7 liter 325 (super eta). The primary difference between these two engines was the cam and fuel injection. (The i revs higher and produces more hp. The super eta is a low rpm high torque engine.) I don't believe a stock super eta motor would run well with an i ECU.

A common upgrade for the super eta motors is to replace the eta cam, intake, and computer with the i parts. At that point, everything changes and all bets are off. The 2.7 stroker should raise your base hp by about 40.

I suppose it's possible that someone did this in the past, but you'd need to look at the cam to be sure.

Just my .02

[Bimmer325e BD]

I really doubt they swapped the cam and everything...could be possible that they swapped the ECU because it was broken into and stolen twice...but the family friends that we bought the car (who were first owner) was a girl that used it as a commute car to college and thats it. Maybe when it was stolen...they had messed up the computer, causing the dealership or something to put a 153 cuz they couldnt get a 154? or something? I'm not sure...maybe that explains why my friend says my car runs like crap (hehas a 89 m3). I always thought it ran good lol. well...as I do have the 153 ecu (325i) I might as well swap the cam/intake because its already started for me then?

[jmc1590]

As far as swapping up to the "i" parts, you'll need to get additional oil journals drilled in the head. (The super eta uses 4 cam journals, the "i" uses 7.) If you are comfortable removing the head, I would follow that route. To use the higher RPM limit the "i" ECU provides, you'll also need to install the stock "i" dual valve springs. (If possible, just replace the entire head with one from a 325i.) There are plenty of threads on this subject. Just Google 2.7 stroker and read up.

Otherwise, as both ECUs are M1.1, the only difference between them should be the chip. Replacing the 153 chip with a tuned one for the Super ETA should straighten things out. This would also allow you to keep all your stock components.

Good luck!

[Bimmer325e BD]

Thanks man...looks like that's what I'm going to do.