OBD 2 B18C1 into a 5th gen EX Question: I have an OBD 1 Civic. Does it make a swap much harder to do by choosing an engine that is obd2? For example, putting a 1999 B18C1 into my 95 Civic EX coupe? I know of the wire harnesses that can be gotten for this kind of swap but i read on a site that it is not recommended?? What are your thoughts on this? Answer: If you get the wiring harness with the '99 GS-R swap all you need to do is drop it in, plug the engine harness in, and add wires for the VTEC solenoid, knock sensor, and VTEC pressure switch. Get an OBD1 GS-R ECU. It plugs right in. For the IAB you will need to move A20 to A17. Since you will be using the OBD2 engine harness and an OBD1 GS-R ECU you will need to cut the black wire at the IAB plug and give it a 12V switched source. You can get this from the yel/blk wire at the injectors or the IACV. The reason this needs to be done is due to the fact that the OBD1 GS-R ECU uses a negative trigger to activate the IAB and the OBD2 GS-R ECU uses a positive trigger to activate the IAB. If you use the OBD2 GS-R engine harness with the OBD1 GS-R ECU the IAB will not work by just moving A20 to A17 (as with an OBD1 GS-R ECU and OBD1 GS-R engine harness).