how do i fix this on my swap
92cx - obd1 gsr with obd1 p72

i still have the stock cat from my gsr with the o2 sensor connected
can i just use that?

 

Did you use the stock wire harness or the one from the Teg motor? You can use any 4 wire Honda O2. The plugs are the same I believe, just some have longer wires maybe. If you used the stock wire harness, I'm not sure it will have the wiring for the 4 wire O2 since yours was originally a 1 wire O2. The ecu needs to see 2 of the 4 wires though.

 

I have a 92 vx. with 99 gsr and running obd-1 ecu. didn't need to mess with O2. but jsut trace your wires, and figure it out. make sure the wires you have plugged to the O2 go to the right pin in the ECU. maybe your O2 is bad. go to :
http://tech.hybridgarage.com/tech/index.html
for help.