im running an obd2 b16a2 with an obd1 wiring harness, and obd1 p72 ecu.

gives a 41 cell. what do i do? where is the problem? o2 sensor?

 

Could be a wiring problem or the sensor going bad.

 

if you have a volt/ohm meter measure the O2 heater (two black wires) makes sure that there is 20-1k ohms.
If there isn't replace the O2 sensor, if there is move on to next step.
Next disconnect the O2 sensor and connect to the O2 heater line at the ECU. Switch the key to run (don't start the car) and read what the ECU is putting out.
If it's ground make sure that the other side of the O2 heater is connected to 12V.
If it's 12V make sure that the other side of the O2 heater is grounded.

 

dont understand, are you saying if its ground on the ecu, it should be hott on the o2? doesnt sound like thats right.....

 

No, what's he's referring to is the fact that a handful of Honda ECU's (I think mainly the OBD1 P72's - but certainly not all) used a different 'voltage scheme' to control the O2 heater. On some, one of those black wires will be tied to +12v while the ECU supplies a ground to the other. On others, one of those black wires will be tied to a ground while the ECU supplies the second wire with +12v.

Because you've done a swap, he's asking you to verify which scheme your ECU uses. So you disconnect the O2 sensor (already disconnected since doing the resistance test above) and then test the black wire that actually leads back to the ECU. Upon determining which scheme your ECU uses, you'll then need to figure out where the other wire went initially (gnd or +12v) and correct if needed.