O2 sensor break-in required?

[FlyNNN]

Is there such a thing? I just replaced mine in a 1990 XJ with 130k. I was not having any problems with it prior. With the new unit in I see my O2 voltage jumping around and the exhaust status quickly changing from rich to lean when monitored on a MT2500. Without looking at the scanner, one would think all is well. If you go to the 3/4 mark of my YouTube video you can see the status for yourself. Suggestions?

http://youtu.be/TExI8YnNWzs


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[Tim_MN]

O2 sensor break-in required?

No.

At idle that voltage should read 1-4 volts oscillating quickly back and forth roughly once every second. At 2000 rpm it should run between 2 and 3 volts max, and is optimally running between 2.3 and 2.6 volts at 2000 rpm (in park). A digital meter can NOT be used for reading the O2 sensor voltage, but it can be used to test the ground and the 12-14 volts to the heater and the 5 volt feed from the ECU with power on and engine off. You must use an old style analog meter with the needle gauge on the display to see the voltage swing back and forth with the engine runing.

 

[LYKOS]

I changed my two upstream O2 sensros recently and saw an immediate drop in fuel economy.

The other day I had my battery disconnected for a while and when I stared driving again my idle smoothed out, the Jeep ran better...

I'm sure it's a noob question but do you have to reset the computer when you change O2 sensors? Or like the OP asked is there an break in period?

 

[Jnida63]

you reset your long term fuel trims when you unhooked the battery, so yes it does make a difference.
the cars computer uses the long term fuel trim data to set the injector pulsewidth.
Most good scan tools can reset your fuel trims.
Driving it for a while will gradually bring the trims back to normal.

 

[Porch951]

Yes, it's generally a good idea to disconnect your battery (reset the computer) when you replace your o2 (or use a good scan tool to do it, as Jnida mentioned above).

 

[5-90]

Is there such a thing? I just replaced mine in a 1990 XJ with 130k. I was not having any problems with it prior. With the new unit in I see my O2 voltage jumping around and the exhaust status quickly changing from rich to lean when monitored on a MT2500. Without looking at the scanner, one would think all is well. If you go to the 3/4 mark of my YouTube video you can see the status for yourself. Suggestions?

http://youtu.be/TExI8YnNWzs


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Not that I know of.

And, while OBD and OBD-II may have an abbreviated "re-learn" procedure, RENIX doesn't care. It will re-learn immediately (if not within 30 seconds or so,) and you'll be off and running.

EDIT - let me know if you decide to part with that MT2500 - I've been wanting to get my paws on one for a while, but haven't had the readies...

 

[magimerlin]

EDIT - let me know if you decide to part with that MT2500 - I've been wanting to get my paws on one for a while, but haven't had the readies...

They are all over Ebay thats where I got mine.... Usually have atleast 10 on there at any giving time.

 

[magimerlin]

and to the OP the readings are suppose to fluctuate. I looked at mine the other day and it was stuck at one voltage reading through out the rpm ranges. I was using my MT2500 to check it. I went into my trouble shooting cartridge set up and found out what it is suppose to do. And it is suppose to fluctuate like you are getting on the new one.

 

[FlyNNN]

... And, while OBD and OBD-II may have an abbreviated "re-learn" procedure, RENIX doesn't care. It will re-learn immediately (if not within 30 seconds or so,) and you'll be off and running ... EDIT - let me know if you decide to part with that MT2500 - I've been wanting to get my paws on one for a while, but haven't had the readies...

Well, OK. So my RENIX ECU does not store any fuel trim history. Therefore, no resets of any kind required. I've only been idling in the driveway since the replacement. I'll do some driving around and see what changes.

Regarding the MT2500, sorry, you'll be waiting a long time. I just got this setup and got some learn'n to do. There are lots available on eBay. $100 gets you in.

...At idle that voltage should read 1-4 volts oscillating quickly back and forth roughly once every second. At 2000 rpm it should run between 2 and 3 volts max, and is optimally running between 2.3 and 2.6 volts at 2000 rpm (in park).

Thanks, gives me a reference to go by.

...and to the OP the readings are suppose to fluctuate. I looked at mine the other day and it was stuck at one voltage reading through out the rpm ranges. I was using my MT2500 to check it. I went into my trouble shooting cartridge set up and found out what it is suppose to do. And it is suppose to fluctuate like you are getting on the new one.

Good to know. My voltages were a lot more stable before the swap. Although, they did fluctuate, just not as much. I do have a troubleshooter cartridge, it just isn't recognized when I plug it in.

 

[5-90]

They are all over Ebay thats where I got mine.... Usually have atleast 10 on there at any giving time.

Yeah, I know. But we're still recovering from assorted medical bills, I can't work for anyone else, things are going goofy for her, and most eBay folks don't want to do swaps...

 

[Jnida63]

http://www.autolabscopediagnostics.com/sensors2.html
it shows how 02 patterns are supposed to look like, a good sensor and properly tuned engine will switch rapidly, at least the upstream sensors (before the cat)

 

[FlyNNN]

...it shows how 02 patterns are supposed to look like, a good sensor and properly tuned engine will switch rapidly, at least the upstream sensors

Thanks for the link. Good information. I guess sinusoidal is the way to go. I wonder why they would design it that way?? Looks like monitoring the waveform on the oscilloscope is the best way to see whats going on. I guess the newer Snap-On's would provide that waveform(?).

After a drive today I hooked up the MT2500 and noticed the injector pulse width time was the most noticeable change, dropping a full (1)ms less. That means less "on" time, less fuel use and hopefully better fuel economy. It'll take me a few gas tank refills to find out the actual results.

EDIT: Spent some time on that wave-form site. Looks like interpreting the waveform on a O2 sensor would be a valuable troubleshooting tool. Sure would be handy to have some kind of "Automotive Scope Meter" in the tool box.

 

[BotakBeng]

Thx for the video.
Just wondering why you would use a thread sealant rather than an antiseize?

 

[FlyNNN]

Thx for the video.
Just wondering why you would use a thread sealant rather than an antiseize?

I wondered myself when I was at the store looking specificaly for an anti-seize product. This was all I found. It said that it has anti-seize properties on the label.

 

[Ecomike]

Thx for the video.
Just wondering why you would use a thread sealant rather than an antiseize?

I have never seen that stuff, or seen an antiseize labeled as sealant?

If it is not labeled O2 sensor safe, it may have silicone in it that can damage the sensor chemistry permanently.

 

[FlyNNN]

I"ll have to contact Permatex and get some clarification on this thread sealant.

 

[Ecomike]

I"ll have to contact Permatex and get some clarification on this thread sealant.

Does it say O2 sensor safe on the container?

 

[FlyNNN]

Does it say O2 sensor safe on the container?

No

 

[5-90]

Thx for the video.
Just wondering why you would use a thread sealant rather than an antiseize?

Anti-seize should have come with or already applied to the new sensor.

I've never needed to wipe it off to apply something else, and the HEGO usually also uses a crush washer to seal, akin to the washers found on flat-seat spark plugs.

Never-seez and 19 pound-feet of torque seem to be the industry standards for HEGO sensors - remove them while they're still warm, and the job is caek!

 

[5-90]

Yes, it's generally a good idea to disconnect your battery (reset the computer) when you replace your o2 (or use a good scan tool to do it, as Jnida mentioned above).

If you're going to wipe the KAM (Keep-Alive Memory) in your ECU, merely disconnecting the battery requires letting is stay disconnected for a few minutes.

Or, just disconnect both battery cables, and touch them together for thirty seconds to drain the KAM caps.

Not generally necessary - and definitely not necessary on RENIX - but that's the way to do it.