My Nissan 720 has an aftermarket wide-band readout lives on the dash. The truck came factory with an O2 sensor that controlled a carb enrichment solenoid - the engineers got the O2 sensor position correct in the exhaust, I assume. It is a one-wire sensor, so it relies on exhaust temp, which was insufficient, at times, when I had the exact same sensor and readout behind my 2F header.
The sensor is a controlled ground, on a microvolt scale. At 600, or whatever, degrees F, right. So, if you have more O2 (not necessarily lean, could just be unburnt mix) then it reads a lower voltage because oxygen can conduct as a ground. Please correct me if I am wrong. But, on my set-up, if I want to have a leaner reading on my dash, I can simply turn on the running lamps. Could be electrical, could be greater alternator load on crank pulley? The point is that if the electrical potential of the exhaust pipe is a bit off from that of the battery negative, it isn't going to work right, it would read lean if the exhaust ground rusted away, or the battery voltage drops beyond a certain range, like when the alternator stops charging immediately when the engine is off. Well, the same thing for a $20 radio in my FJ40 I made from Amazon computer speakers, it doesn't work, or shall I say, it picks up tons of noise, apparently body panels on the truck are so badly grounded that the coil firing creates a tone due to the difference in potential, it changes in pitch with rpm, like an audio type of tachometer. Electrical charge is always relative to its environment, so if the battery positive is doing all this drama when the points-type voltage regulator, way on the other side of the engine and wiring harness, you gotta wonder how that reads as microvolts at the O2 sensor? Can a contact-points type voltage regulator and , in my case from 1975 with original harness, be a 100% compatible match for whatever is reading the O2 sensor? They use solid state voltage regulators for alternators now, is my understanding, and for some reason, my voltage regulator has fewer wires than that of later Cruisers?
My 2F probably burns too much oil for O2 sensors to work properly, but, I can't help but wonder about the temperature range for a non-heated, one-wire sensor, and the electrical environment required. If the O2 sensor itself is cold, the reading will be rich on the dash readout, but, we know that it is just cold. Well, last winter no amount of driving would bring the readings into normal range, still too rich on the dash, and all the driving symptoms are related to a lean-feeling condition, which was easy to fix as enrichment is as easy as putting a vac plug on the line to the power valve.
My best conclusion has been a simple, I don't know, but, I'm still interested in following up on the mystery.
