Im not sure were on the o2 sensor im supposed splice to connect the source wire. Do i splice the black wire coming from the harness? Or the green wire coming from the o2 sensor itself?

 

Black shielded wire. Splice it by the ECU.

Use the ECU wiring diagram to locate the O2 sensor wire. Personal preference, but I cut the wire, & rejoined it w/ a stub wire (so it's a 3 way connection) and soldered it. Then the stub wire is still sticking out to run to the gauge. I have a pic floating around ZDriver somewhere....

 

If you could post that pic id greatly appreciate it, i look for about an hour and couldnt find it. Thanks for the help nismo. Also when i was looking through the shielded wire from the o2 sensor connector back i saw there was splice that had been put back to normal with a double ended crimp or whatever you call it. I assume this was from the previous owner trying to install an a/f gauge. Will the shielded wire being cut then put back together going to cause any problems?

 

The outer shield is just to help w/ radio interference. A lil missing section won't hurt. The black O2 sensor wire goes to ECU pin# 24. See pics ( don't mind the Z31T ecu ). Pic 2 & 3 are examples of my spliced pig tail stub to run to the a/f gauge.