O2 sensor issues!?!

[endeffect0]

Im tossing this up in the newb thread because I have basicaly no prior knowledge of this particular subject.

I threw a CEL that read something to the effect of "too long entering closed loop fuel control".
In conjunction with that my idle has jumped to about 1500rpm. When I did some data logging the O2 sensor signal looks like a cosine wave most of the time at idle and mid throttle, it stops that and starts acting more logicaly under heavy throttel. At times when i glance over at the data logger I'm getting little or no voltage and it drops off the graph entirely.
None of these behaviors seem to come with any additional symptoms or under any specific circumstances...

I dont know if any of this is normal behavior or even a normal way for an O2 sensor to fail.

anyone's opinion (who knows what their talking about) is welcome.

 

[luv2rallye]

Proper O2 sensor operation: O2 Sensor FAQ

 

[endeffect0]

Thank you wise man for the info. Most helpful.

That certainly gives me a base knowledge to work from, and im glad i have the ability to data log rather than voltage test... but i now have more questions.

I now get that the sensors wave pattern is proper behavior.

BUT is seeing the sensor flat line at zero volts at times or flutter around at higher voltage and a relatively flat and high line under load makes me think the sensor is starting to fail or failing in a weird way.

?

 

[luv2rallye]

Yes I'd say your sensor is starting to fail. It should not be flat lining [unless something is wrong that is causing the mixture to stay at the same O2 content for a time period (during the flat line) - but that is not the design intent and is not as likely as a bad O2]. The ECU constantly causes the mixture to be slightly rich and then slightly lean typically at least 1 or more times a second and then uses the O2 signal to monitor the effect (thus an always changing O2 signal). That is how it knows it's injector pulse width and ignition advance are where it wants them to be for proper mixture (14.7 to 1) for the current conditions. And a changing O2 signal also lets the ECU know the O2 sensor isn't stuck/broken/disconnected.

 

[endeffect0]

Thank you,

Given that, I think I'm going to double check that their is no faulty wires that have rubbed through and that their is no gunk on the out side of the sensor that would be affecting it.
Is their any way to clean the exhaust side of the sensor? carb spray, gasoline ect?

 

[spyderturbo007]

You will see the systematic bouncing of the signal during light cruise and idle, which is normal. Keep in mind, that under deceleration you will see the voltage drop to 0, as the ECU shuts down the injectors. At WOT, you should see the voltage of the sensor stabilize in and around the 0.9v range. This is normal, since you have entered open loop.

Once the car is warmed up, what is the reading on your logger for the coolant temp? Make sure you're looking at the logger and not the dash, since they use different sensors. What about IAT?

 

[luv2rallye]

Is their any way to clean the exhaust side of the sensor? carb spray, gasoline ect?

There's various opinions on whether solvents will do any good or not due to the extreme heat the sensor sees. Some say yes others say no. Search internet for opinions and methods. Here's an example: can you clean oxygen sensor? - Ford Truck Enthusiasts Forums.

The best way to clean it is probably as the article in the link states:
"...the sensor may be carbon fouled. It is sometimes possible to clean a sensor in the car. Do this by unplugging the sensor harness, warming up the engine, and creating a lean condition at about 2000 rpm for 1 or 2 minutes. Create a big enough vacuum leak so that the engine begins to slow down. The extra heat will clean it off if possible."

A lean condition can be created by unplugging a vacuum hose that comes directly out of the throttle body.

 

[endeffect0]

for this one particular log i'm looking at (though i have many others that look similar), which is pretty long because it was playing in the snow as well as some road driving.

the water temp around 190degrees +- about 10 i guess..
the intake air temp hovers in the 40s

for the first half or so of this log the o2 sensor cycles about once every half second(peak to peak) it drops to nothing under decell and occasionally gets flatter toward the top under heavy throttle.. fairly normal from my understanding..

About half way though the peaks start to get long up to 3 second for a cycle.. and also sporadically disappearing while the throttle conditions have not changed. right after a full boost period at 4000 rpm (which has happen before in the log with out the effect on o2 and might just be coincidental) the signal drops off and then proceeds to vary around .20v or lower for the rest of the time as a mostly flat line with no cycle.. though does move up from just about nothing to .20 or so mimicking the arch of boost under hard accelerations, sometimes.

that is probably the best i can describe the behavior unless i come up with new info in other logs.

 

[JoEgsX90]

I have a similar problem, and im wondering if anyone can tell me the proper o2 voltage that i should be looking for with my PALM logger. Im new to logging so sorry. Im using Palm n stein Under my o2 valtage whats normal vlatage at idle and wot?

 

[endeffect0]

O2 Sensor FAQ should have all the information you need as far as the voltage outputs .. i dont know why it would be different for a pocket logger..

 

[endeffect0]

Anyone have any thoughts at what would cause the above mentioned behavior.

i checked all the wiring today and found no issues. I'm going to try some of the various cleaning techniques tomorrow and see if that yields results unless anyone has suggestions.