Rear oxygen sensors

[yzfr6i]

Do the rear oxygen sensors (post-cat) have any affect on fuel trims, or do they just monitor your catalytic converter. This is on an 02 GT.

 

[DeepList]

Both front and rear sensors give feedback to the ECM about the air/fuel mix. The rear sensors tell if there is too much fuel that's not being burned. If you want to eliminate them, you can use MILs, but that usually causes check engine lights. You can always do what I did, and just turn them off completely in the tune.

 

[yzfr6i]

I'm currently running no cats, and MILs (with no check engine light or codes). I've replaced both front O2s, but both my rear O2s look to be original to the car (170,000 miles).

The reason for my questioning is because bank 2s fuel trim levels (short & long term) are far higher than bank 1s, which are near perfect. Also if you let the car sit and idle at a stop light for a long time you will get a puff of smoke when you leave. Or if you idle around in a parking lot you will get some smoke as you're backing into a spot.

 

[g36 monkey]

fuel smoke or oil smoke?

 

[yzfr6i]

unfortunately at a car show last nigh my son watched me back into a spot and he said it was blue smoke and smelled like a two stroke dirtbike.