heated oxygen sensor

[TP757]

I have a 97 gsx awd with a dohc 2000 turbo engine and i'm trying to install a A/F ratio gauge but i'm having problem finding the signal wire from the heated oxygen sensor because it has 4 wires, 2 Black cables with no stripes, 1 blue and 1 white. if anyones knows which is the signal wire please let me know thanks for ## help!!!!

 

[luv2rallye]

http://www.dsmtuners.com/forums/articles-electrical-wiring/244376-oxygen-sensor-wiring.html

 

[Defiant]

We strongly recommend discarding A/F (Always Fluctuating) gauges unless you're running a wideband O2.