so i have an s52 in my 328is, but no m3 ecu.... i wanted to do the m50 manifold conversion, but was wondering if i should swap the ecu first? is there anything else i could do like get it reprogrammed by a tuner for cheaper? i dont have that much to spend but the gas mileage seems like its suffering ALOT and the cold start issue is starting to get on my nerves

What you need to do is look at the ECU. Find out what color the label is, and the last three digits of the code and we can help you. It would also benefit you to open up the ECU to see what chip is in it.

Oh and why does it say a 323i in your profile but you said you have a 328is? Aren't we close? I cold probably help you out a bit in person if we meet up, aren't you in Stamford?

yea bro im gonna check tomarrow.... but i had an e46 323i then i got rid of it and got into this car

The 328is has an OBD II ECU and the chip is not something you can inspect or swap. These ECUs have to be updated using something that plugs into the OBD II data bus. Your problems running the S52 are due to the fact that the ECU is coded for the 2.8 liter M52 engine and its injectors. The S52 has larger injectors and you are probably running way too rich under most driving conditions. You need an M3 ECU or some way to get your 328 ECU recoded for the S52 engine. Not many independent shops can do this. Dealer can do it but around me, they won't touch a conversion car like this. I know, I have a 328 with an S52 engine conversion. I bought a used M3 ECU with the engine.

Mark
95 525iT w/S52
97 328iC w/S52

The S52 does not have larger injectors than the M52.

The S52 does not have larger injectors than the M52.

IIRC, they are both 21.5lbs.

s52 m3 sharked ecu for sale, ramironoguerol@hotmai.com