Can I use a 93 Civic Si wiring harness with a 95 GSR motor.?? The only plug the Civic Si harness does not have is one on the backside upper part of the block.? seems to be right near the intake manifold. Anyone know what this is for and if I need to add anything to the Si harness for the GSR motor. i know I should use a GSR harness if anyone has one for sale I 'd trade a GSr diffenrential with a Phantom grip for a complete unmolested GSR engine bay harness for an OBD1 motor.

 

i believe the D16Z6 harness can be used with the B18C1, but that wire you mentioned not being there is probably the knock sensor wire. only the DOHC VTEC motors have the knock sensor located on the back of the block. you'll just have to run an extra wire from the block to the ECU inside.