I have a 98 civic HX (d16y5). I have a OBD 2 to OBD 1 conversion harness and connected a P06 ECU. The car ran awful and the check engine light came on instantly. The car is a manual and the P06 ECU is also manual. the conversion harness was professionally made and ordered for my car specifically. I know the HX is a bastard child. Can anyone tell me why my car may be running so badly.

I read a few things online about the HX only running 12 valves until in vtec mode then running all 16 valves. does this have anything to do with why the car can hardly even idle when the OBD 1 ECU is running it?

I'm rebuilding a d16y8 head to swap onto my block at which point i will need a new ECU to run the car. once the new head is on. will the P06 run the car smoothly? I will have a vtec controller on there since the P06 is a DX LX ECU then i will send out another P06 to get chipped with Hondata once i know the car runs ok.

So in short... is the reason my car runs like crap with the P06 because its a HX??