narrowband readings

[mexicanzero]

so i know that narrowbands arent very acurate or good buuut
i got one cheap and decided to hook it up

now i know there is supposed to be oscilation from min stoich to max stoich but i thought it wasnt supposed to go below or above when at idle.
then on accell its supposed to go slight rich and on decel slight lean right?

with engine warmed up and everything at idle i'm seeing from off the gauge lean to 2 bars rich oscilation and randomly it'll just stop at lean or rich for 10 or so seconds

while at part throttle it was oscilating from very lean to max stoich and once in open loop mode (at 3000 rpm or so) it'll shoot up to 2nd or 3rd bar of rich.

i've never had a narrowband or any kind of a/f gauge but am i wrong in thinking that my o2 sensor might be poop? cuz its i think under a year old... is there anything else that can cause these issues only in closed loop?

thanks
-Alex

[beatersubi]

It sounds like everythings working correctly. Does the gauge have a voltage reading? If its oscilating slowly you might want to try a new sensor.
A stoichiometric mixture for gasoline is 14.7air:1fuel. More air, i.e. >14.7 is lean, and <14.7 is rich.
A narrowband only reads a stoich mixture which = .5v. Anything leaner is less than .5v and anything richer is more than .5v. However, the voltage output isn't directly relatable to how rich or lean the mixture is. Anytime its bouncing from lean to rich, the ecu is in closed loop mode and is working to maintain a stoich mixture. During on-boost acceleration the ecu enrichens the mixture (for engine longevity). During closed-throttle deceleration the injector pw is 0, so the mixture will be lean.

[mexicanzero]

its just the fact that its going so lean constantly that worries me.
what controls the extra fuel when on boost? the map sensor? or just the maf seeing more air going through?
i unhooked my o2 sensor today and was seeing richer mixtures than with it plugged in obviously but my car was running better!

with the O2 plugged in no matter what psi until i'm close to 3000 rpms(open loop) it keeps oscilating very lean to max stoich, going up steep hills sometimes i hit close to 10 psi and am still seing lean to stoich on the gauge.
and then when it hits open loop mode it suddenly richens up and shoots the car forward.
when i unhooked the o2 sensor i was seeing slightly rich as i was hitting 1 psi and it got a bit richer as i approached 10 psi
the throttle response felt alot better and more progressive. not jolty. and the car just felt like it was running as it should.

i'm thinking maybe my O2 is ok but whatever is supposed to richen up the mixture on boost isnt doing it right.

any insight to that?

[ericem]

Maybe it is time for a new o2 sensor. Is yours oem?? I think bosch is oem. Wouldn't hurt to try removing it and cleaning it with o2 sensor cleaner.

[beatersubi]

You should chech your MAP sensor. Make sure the vacuum lines to it and the other sensors are routed correctly. And check its signal voltage against your boost gauge, if you have the means.

[Legacy777]

To be quite honest, you're wasting your time. A narrow band O2 sensor is not going to give you much if any meaningful data.

[mexicanzero]

i got a downpipe comin in the mail so i'll just get a new o2 for it when i put it in

as for the map i know all the lines are routed correctly but as for checking voltage vs boost do you have any idea of what the specs are? i've looked a bit and havent gotten anything useful.

does it control the "extra" fuel when on boost? or what does?

and i know narrowbands are just pretty lights but i'm also in search of a goofy driveability problem which i thought i had solved in another post ( http://bbs.legacycentral.org/viewtopic. ... 539#282539 ) since i found my bpv stuck open at all times, so bleeding off boost. but after driving around for a while the problem is still there, just not as bad. and i dont think fuel trim relearning should take this long, so theres gotta be something else off.

thanks for all the help so far
-Alex

[beatersubi]

A n/b is inaccurate at anything other than stoich, but it will tell you whether you're rich or lean. And you should be running rich on boost. If you're not, there's a problem.
I don't know specs on MAP output v's, but they're probably in the FSM. You might also look at fuel delivery. If the engine isn't getting enough it'll cause a lean condition. If the pump is original, that'd be a good place to start.