O2 Sensor...

[nissan200sx.dk]

Hi there.

Im having a bit of trouble with AF values all over the place. one day its fine, later its really lean, later again its fine. sometimes my AF gauge show somethinig, sometimes it dont. :S

Have a LM1, so do know my actual AF.

All this are a idle or cruising, when flooring it, or disengaging AF feedback in my PFC its okay... So figured it could be my O2 sensor.

Had a spare, so changed it.

Checked in my PFC, it shows ~0.12v at idle constant.. only changing a little up and down. ~0.05v.

When i started my car, it was up around 0.6v, then steadly lower, still being a little up and down. ~0.6 - 0.3v. then after some minuttes it settled at ~0.12v. ~14.7 A/F on the LM1.

What do you recon is the issue. some kind of wiring issue? because of funny way AF gauge is acting, it reads the signal from std o2 sensor... LM1 has its own sensor.

What to check?

What kind of power goes to the std o2 sensor? can I check at the plug?

Have searched around, but can´t find a answer.

Thanks.

Edited December 12, 2007 by nissan200sx.dk

[nissan200sx.dk]

No one?

[Amec]

No one?

once warmed up, the o2 sensor should constantly go up and down in voltage, it should never flat line. if it does, it's cactus.

[R31Nismoid]

Doesnt do anything really anyhow that requires it to be there

[nissan200sx.dk]

Thanks.

in two weeks, i will be changing engine block, at that time I will take complete engine wiring out, and check it.

its acting funny.... more seems as a bad connection somewere.

[MrStabby]

+1 to Amec

When in closed loop mode the reading from the o2 sensor should fluctuate wildly as the ECU keeps slightly richening then leaning the mixtures to get as close as possible to stoichiometric. Narrowband o2 sensors really only have two states - rich and lean - which result in two very different voltages. As the mixture flicks between rich and lean the voltage jumps up and down. Your LM1 will have a wideband sensor in which richness/leanness is proportional to voltage, so you can get a value out of it. My guess is that the spare you put in was stuffed (was it new?).

There is a long thread in the General Maintenance on o2 sensors. Get a six pack and wade your way through it....

[nissan200sx.dk]

the narrowband o2 sensor is the std rb25 sensor...

was there when I bought the engine. ;-) hehe.

But have tryed changing o2 sensor, and still the same reading...

Will have a look on my wiring when I get the time.

I use the LM1 hooked up to my FC box to log and adjust.

[nissan200sx.dk]

just checked my wiring, as stated in r33 workshop manual.

o2 sensor diagram, and checks to do are okay.

exhaust gas heater check is also okay...

What is the difference in theese 2 by the way?? did both tests at the same o2 plug....

Have tryed 2 different o2 sensors, the one I got with the engine, and the one I got from a spare engine I bought.

Could they both be dead? Its a little expensive to try and buy a new one.... and dont know anyone with a R33 here in denmark.