SCMFOX

Feriohhh

Just use an OBD2a P73, which should plug right into your harness. They're widely available and inexpensive. Also, Both OBD2a and OBD2b use three connectors.

JRCivic1

OP, are you in the US ???

SCMFOX

JRCivic1

OP, you need a GSR ECU from an appropriate model vehicle that has the same type of ECU plugs as your chassis. I don't recognize a "PX3" ECU type, so I assume this is from another market outside of the US. Some pictures of your current ECU plugs might be helpful... let's see what you have.

SCMFOX

From my 1997 honda civic ej9

only two ports

what needs to go into my civic. P72 ECU

Freedo_Civegra

JRCivic1

Oh boy... your ECU has TWO (The "A" and "C" plugs) of the three OBD-1 style plugs normally found on a '92-95 USDM ECU... in a 1997 EDM chassis !!! The smaller (B) plug you are missing has a LOT of important wiring in it here in the US... like all of the distributor sensor wires. Typically, you will find 10-12 wires in that plug. I don't know that I have ever seen a plug and play conversion of some type that connects the engine harness to the ECU that you have. This makes me wonder if the basic mechanical function of your car's original engine is drastically different from the GSR's... like carburated and a TDC sensor only in the distributor.

Maybe the thing to do would be to get a USDM OBD-2A engine harness that matches your green crossover plug and build from that. Take a close up picture of the chassis side of the green crossover plug seen on the left side of your second photo above and post it... and a good shot of the junction where the engine and chassis harness connect in the engine bay OPPOSITE of the side where the engine harness comes through the firewall and terminates at the ECU.

JRCivic1

Was your car automatic before you did your swap ???

SCMFOX

My vehicle wasnt at anytime auto