I posted in FI, but haven't got much of a response...
My set-up:
d16z6 with a t3@7psi, intercooled.
Bosch BOV
DSM 450's with homebrew fuel trim circuit.
Stock timing.
zfr6j-11 plugs
Basically, I'm pretty sure the car is running rich (lots of vapor/gas/black-**** coming out of exhaust).

My EGT is around 900-1100F cruising, depending on speed, and it peaks at around 1500F after a hard run through a few gears, so not too high.

The car also bogs/lurches a little when you transition from low to high throttle and/or from vac. to boost.
However, my o2 voltage is rich at idle (.8-.9v) but, then goes negative! when I use barely any throttle...
The sensor is 1month old, Denso OEM replacement. Is it bad? I'm pretty sure it's wired up right, since it's working at idle and part throttle...or am I just HORRIBLY rich?

I need a little input here to get it running decently, since I don't really have the money to bring it to a dyno right now...any help would be GREATLY appreciated.

 

so, basically...does a negative voltage from the o2 sensor mean it's rich, lean or fucked?

 

Alright, after doing some searching...an o2 sensor can put out a negative voltage if the "air reference" is clogged. This seems to be the prime candidate for my problem, because the entire sensor was being exposed to overly-rich exhaust before I had the downpipe connected.

The only question now is; what is the air reference? The small hole toward the harness end of the sensor? How would one clean this, or is that not possible? Anyone? Can I get an 'Amen!'?

 

The more voltage the o2 is producing the hotter your motor is running therefore running leaner. Pull your spark plugs and the o2 sensor after a quick run, you should be able to tell how everything is running somewhat from that. Also that's weird, I don't think i have ever seen a o2 create negative voltage.. You are putting the positive on your voltmeter to the white wire and grounding the negative right.

 

I don't believe it has anything to do with temperature, actually. It actually measures the oxygen that is unburnt in the exhaust, correct? In any case...
Yes, that is weird, but after looking, it apparently happens if it's cracked or if the air reference (source of atmospheric air that it compares exhaust gasses to) is clogged. I am certain that my a/f meter is hooked up correctly, because it worked perfectly fine when I was N/A and it still gives a real (though rich) output at idle and part throttle.