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Needed some info for 05 nissan quest 3.5L afr sensors there are 2 upstream afrs, what is the normal voltage range of them? than the 2 downstream o2 sensors are they used to fine tune the fuel control,or just to see the health of the cat? Its got 130,000 miles on it new dealer plugs in it,no mil light on with no pending codes, with long term fuel adding 8+ fuel it really seems like an vacuum leak, but ive smoked the engine no leaks plus carb sprayed it nothing. The car runs very good no missing at all but using way to much fuel. Would appreciate feedback thanks.
Depending on the scan tool used , Nissan A/F sensor stoichiometric voltage is 2.2volts... BUT, you must also watch to see what desired and actual lambda values are e.g. if desired lambda is .980 then your A/F sensor is going to read around 2.125..... Not sure about the downstream o2 sensors having much to do with "fine tuning" fuel trim, but I would assume that if you cleared the adaptive fuel trims or as Nissan would call it "self-learn cont." and your fuel trim shoots directly back up to 8% (or A/F Lambda 108%) then you could most likely rule out the downstream sensors.
