testing oxygen sensor
 

I am testing my o2 sensor to try and solve my emission problems, I have seen 2 tests, one in the Haynes manual, and the other in the Honda Shop manual, and both say you should warm up the engine, then measure the voltage coming off the sensor wire, holding the throttle at 5000 rpm it should go above .6 volts, and on deceleration it shouldn't drop below .4 volts. I was wondering if this is the best way to do this, when we tested it, it went above .6 for a little, then stayed around .4 on the deceleration, is this right? is there a better way to test it.

thanks

Well i bet you dont happen to have an Oscilliscope laying around so drive the car around till operating temp and have a friend backprobe into the ecu (C16) and watch to see if the voltage fluctuates (if thats how u spell it) between .1-.9, anything above .9 and your o2 is shot. Good luck, BTW what are you not passing on ur emmisions test?

Yeah i too was wondering if my o2 sensor is shot because my car just barely passed emissions and i installed an autometer air/fuel ratio guage and unless im wide open, the guage is all over the place and into the lean area...not sure if thats normal or not.?

Lean meaning your NOx is pretty high when u are doing emissions. So it almost failed e-test on your nox rite O'MALLEY_808?

yeah the limit was something like 68 and my car read 68. Someone told me that the air/fuel ratio guage is supposed to be all over the place when driving normally because everything is constantly "changing" or "readjusting" but agian im not sure

forgot to mention that if im WOT the guage reads rich...srry not trying to steal post just having the same problem :shrugs:

do you gotta digital or analog A/F gauge? you're gonna get some fluctuation as your ECU cycles between open and closed loop modes...If it's digital you're gonna see the numbers jumpin around for that reason. I don't own one, but I've seen videos of supras doin drag runs with em and even at WOT they're bouncin around a bit...digital you may tend to notice fluctuations more than analog....

during WOT you're engine is in open loop mode so you're gonna be rich unless you got a way to lean it off but I think a stock ECU is gonna be a lil on the rich side for safety and durability.

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At WOT it should be on the rich side. You want it a lil richer for max power. As mentioned above.

On decel however I think it should stick quite lean, cuz at high enough revs ~1500+, closed throttle and high vacuum the computer shuts off the injectors. So only oxygen is going through the exhaust system. So it shows up lean.

At cruise you pretty much want it to fluctuate between .1-.9V, as mentioned above. Quick fluctuation generally means the O2 sensor is working well. Slow response or sticks lean/rich however means it's a lil "lazy" and should be replaced.