Si Ecu Help!!!!

I bought a 99 civic SI ecu (P2T) and I assumed that it would fit my brother's 96 civic ex. It didn't. Why? Cause I heard that people switching ecu and stuff but I didn't look close into it. Can someone help me out. What should I do with the ecu? It's available for sale if I dont make it fit. Let me know. thanks

I don't think the Si is swappable with the EX because of the DOHC and SOHC differences. Correct me if I'm wrong but that's just what I've read.

cause i had a obd2-obd1 conversion harness with my obd1 gsr ecu and i plugged it in my bro.'s car and worked fine...so I thought obd2 si would be find but one of the plug in couldn't plugged in (the smallest plug) Weird.

the ecu for the si(P2T) is OBD IIb whereas any civic 96-2000 other than the si uses ODB IIa. check www.hondata.com, they have pictures regarding the differences.

the ecu for the si(P2T) is OBD IIb whereas any civic 96-2000 other than the si uses ODB IIa. check www.hondata.com, they have pictures regarding the differences.

BINGO! That's the answer.

Also it sounded like you were trying to plug the OBD1 adapter into the Si ECU? :confused: If so, you can't plug OBDI plug into OBDII ECU.

Also of note, an Si DOHC B16 ECU most likely WON'T work on a SOHC motor, as there is different control due to the 2nd cam of the B16, which your D16Y8 motor lacks, even though it still has VTEC.