Thread: Wideband behavior

Finally got around to getting a wideband. Went with the latest AEM UEGO.

AFR is fairly stable (within .2) at idle, also fairly stable once into power enrichment.

But at highway cruise it steadily oscilates from (at most) 13.9 - 15.1. When this is happening I notice my LTFT and STFT's are locked in at 0.

Does this seem normal? I didn't expect to see that much fluctuation.

Probably not normal. 15.1 is common, but 13.9 is pretty rich. Maybe your narrowband o2 is bad since your trims are at zero.

Originally Posted by GTPpower

Probably not normal. 15.1 is common, but 13.9 is pretty rich. Maybe your narrowband o2 is bad since your trims are at zero.

Did a quick data log, narrowband seems to be responding like it should.

Made a quiick little video.

https://www.youtube.com/watch?v=SYxDAvMSFXo

Looks just fine.

Look at how quickly it's changing, it stayed at 13.9 for maybe 0.1 of second. Please tell me how it's abnormal.

We also have 6 cylinders going to one wideband and o2 sensor, all it takes is one cylinder not burning as much fuel as the others on one revolution to make it do that.

Originally Posted by GTPpower

Probably not normal. 15.1 is common, but 13.9 is pretty rich. Maybe your narrowband o2 is bad since your trims are at zero.

This is what I thought when I first read this.... I have tuned a few cars with WB and it most of the time stays north of 14.5 when cruising. And both your STFTs and your LTFTs should not lock at 0.0 while cruising around.

Pcm is constantly switching lean to rich n back...on either side of stoichiometric 14.7.
its normal

Thanks guys. I was kinda thinking it was normal, just wanted to make sure. I tend to worry about nothing.


On another note, I have the sensor installed in the rear o2 bung in my zzp downpipe (no cat). Is that acceptable, or should I have another bung welded in closer to the engine?

It's fine.

Originally Posted by 2004l67

Thanks guys. I was kinda thinking it was normal, just wanted to make sure. I tend to worry about nothing.


On another note, I have the sensor installed in the rear o2 bung in my zzp downpipe (no cat). Is that acceptable, or should I have another bung welded in closer to the engine?

Same gauge in the same location for the last ~3 years with no issues and the same kind of reading you are getting...

Use it to tune WOT and the NB to tune idle and city driving.