i had a question about and ecu. i just got a hold of a 2000 civic si. and i know it is obd2. should i go to obd1? is it hard to go obd1? what kind of conversions are there? or is it as easy as buying a obd1 and finding a jumper or something...?

 

you could but it would be alot of trouble like changing injectors/mainfold/intake/ecu etc.. why would you want to do this ?

 

^
nvm, Fabrik8 chimed in

 

Actually, unless there is a reason that you need ECU tuning, then stick with the stock ECU. If you need tuning when you mod the car, look into getting a P30, it's the OBD1 equivalent of your P2P (P2T?) or whatever ECU is in there (I forget).. There is absolutely no performance advantage to switching ECUs between OBD generations if you're not going to get it chipped and tuned. An P72 is a bad choice, you absolutely must get it chipped to disable the IAB (secondary butterfly) output, and the ECU is mapped for a very different engine. A P30 is a drop in replacement from the 94-95 (and other cars in other countries) B16 del Sol. All you need is an adapter harness. Again, there is no performance advantage until you get it chipped and tuned.
I'm slightly partial to the JDM P30, it's more aggressively mapped than the USDM version. You could also get a USDM P30 and get it chipped with the JDM P30 program though, either way.