OBD0 engine have 2 O2 sensors. one on exhaust #1 & #4 and the other one on #2 & #3, both before the collector. The ecu also have 2 pin for o2 sensors the primary os pin C16 (white cable) and the secondary pin C8 (red/blue cable). My questions is which O2 sensors goes into the primary pin (C16 pin), the #1/#4 or #2/#3? thanks.

 

Maybe try the board for whatever specific Honda this is. MOST OBD-0 & OBD-1 cars have only one O2 sensor. Your arrangement is a little bit unique.

 

I tried that but never got a reply also. The engine is from JDM Integra Xsi 1989/90.