Can a wideband O2 be installed in the rear O2 bung?

[RGurleyJr]

Instead of welding a bung near the l/t headers, can it be screwed into one of the rear O2 bungs? The a/f ratio doesn't change within a foot does it?

 

[the98stang]

Instead of welding a bung near the l/t headers, can it be screwed into one of the rear O2 bungs? The a/f ratio doesn't change within a foot does it?

No, you can't put the wideband sensor in the stock o2 bung. It needs to be in between the upstream cats and exhaust manifolds to get the best reading.

 

[LaserRed01GT]

The closer to the collector the better, but if you cannot get a bung welded right after the collector then the next best place is the rear O2 bungs considering you don't have cats. If you have cats, you will not be able to place the wideband sensor after the cat because the cats release oxygen and will severely skew the readings. If you have cats, you will have to weld yourself a bung close to and right after the collector.

If you end up welding bungs, make sure that you weld the bung so that teh sensor will sit upright or at least upwards at 15°. This prevents moisture from collecting between the sensor housing and sensor element which can damage the sensor.

EDIT: And yes a few feet will change the readings. The cooler the exhaust gas gets, the less accurate your readings will be.