It's OBD0, Besides adding wires off of the pw0 ecu for vtec to work, are there any wires coming off the ecu that need to be changed, I think I remember something about the knock sensor pinout runs off of a wire originally that was something else on the pr4 nonvtec ecu. If any of this doesn't make sense please just tell me exactly what I need to do in order to swap a pr3/pw0 ecu into a nonvtec pr4 teg 90-91. Thanks

 

ttt

 

just add 2nd o2 sensor, oil press switch, vtec selenoid, and knock sensor, very simple