hey guys I got an a/f gauge, i would like to hook it up to my sr o2 sensor, this is not a wideband and I am not gonna use it for tuning, its just to tell me if im leaning out or not (YeS I KNOW WIDEBAND IS BETTER), now theres 3 wires on the SR o2 sensor, black one in the center and 2 on the sides, which wire of those 3 do i hook the signal wire to ? I would also like to hook it by the ECU rather than under the hood… let me know asap thanks, my car is kinda shaky in low boost…
ECU Pin #19 = Oxyen Sensor input (O2) - White Wire
So the White Wire on the Sensor etc is the “Signal Wire”
good luck 
Can’t hlep you directly but I will give you some advice.
Narrow band gauges are useless.
I’ve only seen it once in someone’s car and it just kept bounding around all the time. I don’t understand how that’s supposed to really help you.
Didn’t your gauge come with a manual though?
hooked up to the ECU it will donothing, all your doiing is tapping into the ECU’s continuous updates it will go lean and rich and balance out way to fast for it to be useful, you need to go with a single wire o2 sensor and plug it into the DP to get anything apporching a reasonable use. hook up the guage , with the single wire O2 ( any 86-91 rx7 has em ) just like ou would a temp or pressure sensor, except that you ned to add in a 2nd O2 bung. Plugging it into the ECu will give you a nice light show … for ~2 min… then normal people get pissed and blow it up.
well tech @ WOT it should stick @ rich and not bounce back and forth
@ 1/2 throttle it may bounce between stoich - rich rather quickly and if you let off the throttle completely then yea it’ll sit @ lean
but really a narrowband gauge wont tell you shit (you are right) but as long as its sticking @ rich while your @ WOT then its giving you a “pretty good idea”
but also if your O2 Sensor is failing and the Voltage starts to drop, then your “narrowband” gauge would read incorrectly
all this will tell you is if you are leaner than 14.7:1
at 10pounds of boost thats way too lean. so it might be saying full rich and you might still be ridiculously lean
dont do this pointless mod and just LISTEN TO US
YOUR ENGINE IS FINE!!!
narrowband a/f gauges are a pointless gimmick