Symptoms of a bad O2 sensor?

[DrtyRat]

I have an ongoing prob. w/my s14 sr. For a while now its been difficult to start, have to give it gas to start, and between 3500-4000rpms @ WOT it starts to break up bad, but no noticeable smoke. The car idles pretty well at about 900. I've had the car checked for boost/vac. leaks, changed the spark plugs(gapped to 28), got a new air filter, replaced the maf, and got a new coolant temp. sensor, all to no avail. The car runs rich due to an atmospheric bov, and the timing has been advanced, by my mechanic, to help w/the stalling that occurs w/my bov set-up.
I'm running out of options as to what could be the prob. Searching has given me many mixed answers, most of which I've already tried.
I've been thinking about it lately, and was wondering could this be a bad O2 sensor? Are these the symptoms of one? I know the car running rich is not good for it, and my gas mileage is bad enough as it is. So basically I was wondering if running rich, like I've been, would foul the O2 sensor, and if it does, do the problems I'm having seem related to this?
I've only seen the CEL come on once, and wasn't able to get the code off of it, so I'm kinda having to make educated guesses. My mechanic is the only one that I let touch my car, but he doesn't do it full time, so I'm trying to do as much as I can on my own.

[Vision Garage]

A bad o2 sensor will cause irregular idle as well as dying when you start the car. It will also make your car run like crap such as when you step on the gas pedal. So change it anyway, its not much.

[mRclARK1]

Is it still the original O2 sensor that came with your SR? If so, it's likely no good...most motorsets have shot sensors it seems.

[DrtyRat]

as far as i know, its the original. it was a very new motor when i got it (its a kouki), how long do they genrally last, and could running rich cause it to go bad?

[RedtopTech]

At wide open throttle the oxygen sensor has no effect. The computer only uses it to compensate during cruise and part throttle acceleration.

[240tek]

Have you checked you injectors including the pintle caps, and the seals? Think of a windex bottle spray (good), and stream (bad, sloppy rich condition). The culprit injector would correlate with charcoal black on bad plug. What temp range plugs you running? Fuel pump condition, clean?

Run some Seafoam in the intake/ fuel systems, aside possible weather changes....

[DrtyRat]

At wide open throttle the oxygen sensor has no effect. The computer only uses it to compensate during cruise and part throttle acceleration.
I read this in some of the searches I did, which is why I wanted to know for sure. I wonder what it could be....this is driving me nuts b/c I've been dealing w/this for quite some time now.
Have you checked you injectors including the pintle caps, and the seals? Think of a windex bottle spray (good), and stream (bad, sloppy rich condition). The culprit injector would correlate with charcoal black on bad plug. What temp range plugs you running? Fuel pump condition, clean?

Run some Seafoam in the intake/ fuel systems, aside possible weather changes....
Haven't checked the injectors yet. At first the car was very difficult to start, as referenced in my first post, and eventually the breaking-up at WOT followed sometime after that. I would think if the injectors were bad then all of this would have happened at the same time, no?

[kota2240]

I had a bad 02 on a ca18det motor, it would idle fine all day long but you could not drive its since it would break up so much around 3-5k rpms and flood the motor. I changed the o2 and it ran great after that

[opponheimer]

At wide open throttle the oxygen sensor has no effect. The computer only uses it to compensate during cruise and part throttle acceleration.


Right +1 for you. So you can't check CEL Codes/clear it?

I had the same prob but gapped my plugs to 0.25, fixed it. In your case its probably something else. You ever checked timing?

[240tek]

You would have also seen lots of white smoke as well if injectors. I'd rule it more toward fuel pump, if you check your fuel pressure and it's off.

[Dream240]

Bringing this one back for some help.

This past weekend I did some more diagnostics on my stumbling acceleration problem. I rechecked ECU codes, nothing. Ran through the diagnostic steps in the FSM for hesitation, nothing.

Then I ran through the self-diagnostic II steps for checking your O2 sensor. The wierd thing I'm finding is that the req'd CEL light on/off at least 5 times in 10 seconds, well my car will sometimes do it and when I let off the gas and try it again I get either a constant CEL light on or off. So basically the test will fail or pass randomly.

I've checked both the voltage and ground signals coming from the sensor & harness and both are reading correctly.

My question is, does an O2 sensor randomly go bad, then work? On hot days the bogging/hesitation is really bad. It's wierd because I replaced the sensor less than a year ago with a new Bosch unit. So who thinks I should replace my O2 sensor again? I'm just asking cause I'm really tired of buying parts that aren't fixing the problem. Yeah it's been a rough past couple of months

Any advice would be helpful. Thanks guys.

[milk_with_pulp]

im having the same problem ive replace just about everything in the fuel system what is the timing specs and how do you check it and or change it

[s14freak93901]

friend has an S14 SR in his coupe and it would bogged under cold start but once it's warm it would idle fine. everything was good wiring wise. he was never throwing a code neither. we started unplugging things that would cause it. once we we unplugged the o2 under cold start it would hold idle. the end of the 02 was smashed and wasn't getting a ready. still not sure why the led didn't come on.

[chiboy002]

im having the same problem ive replace just about everything in the fuel system what is the timing specs and how do you check it and or change it
why did you bump a 3 year old thread?