Installing an air fuel gauge and need to know which wire is the o2 sensor wire which I need to tap into. Also, does it run into the back of the computer and if so which port and what color. It appears that there are 4 wire in the o2 sensor.

I have a 95 z28

 

purple is the one you need for the gauge.

 

is there a power supply behind the glove box to tap into

 

i run the purple lead through the firewall to the o2 sensor

 

There is an "aux B+" wire located under the center console that can be used.

If you are hooking up an A/F gauge like the Autometer #3675 (http://www.autometer.com/cat_gaugede...earch&gid=3531)
that utilizes the stock O2 sensor (narrow band) unfortunately, you really won't get much useful information from it, although it may put on an impressive light show.

Yuo may want to consider saving up for a wideband style A/F ratio gauge so you can gather some more useful data for tuning.