I had a zetronix wideband hooked up to my car recently.

The sensor was hooked up to my catback bung, and was wondering if this was a sufficient place to mount it?

I ask this because my afr reading at idle is 21. A local tuner told me this was abnormally lean.

 

If you have a cat installed, the sensor needs to be placed ahead of it. Exhaust gas continues to be processed in the cataltyic converter, changing the "AFR." Your tuner should have told you about this.

 

also you could have a bad exhaust leak, installing it in the wrong place will prob net this afr...21 is madd jdm lean...

 

im running a test pipe, so the cat isnt the problem.

i'll check if there any exhaust leaks

 

there's a ton of lean idle AFR threads lately. I'm curious how many people that have this problem have aftermarket cams since i'm noticing a trend. i myself still suffer from this problem even after correcting an exhaust leak.