The old stock manifold has the o2 sensor bung where mounted so the whole tip of the sensor is in the exhaust path. The last 2 headers I have bought, pacesetter and Thorley (current) have the bung mounted so high up that none of the sensor tip is in the path. This is causing my cel to come on at a steady cruise and I am sick of it and want to fix it. I was wondering if some of the o2 sensor tips were longer on some brands or if I should ruin the coating on my header and have an exhaust shop cut down the bung on the header.

 

What would happen if you moved the O2 sensor downstream... beyond the header? Maybe plug the header port and then have the exhaust shop add a bung to your exhaust pipe.

Would save the header and might give you the depth you are looking for.

Although, I would be interested to hear if the depth would really make a difference.

 

If you were to look into the tube, you wouldn't see any of the o2 sensor. It's not getting the right flow. That's an idea, I can have a bung welded onto the midpipe. That's how the pacesetter's was but it was a high mount also.
Here you can see how high the bung is off of the header.

 

I'd just weld the $10 bung (if that) into the header at a more appropriate location. There may be 02s that are set to go deeper, but I don't have a part number for ya...

 

I am not an expert of what the O2 sensor is looking for, but in your pic it seems to be monitoring only one cylinder.

I'd think the computer would need to monitor them all in order to operate properly.

I'd move the sensor off the header or at least after they all join together.

You sure that's not a bung for something else.... emissions maybe?

 

I would put it after the header before the cat.. just plug off the bung on the header (make a plate) my downey header on my 22re is the same way but its blocked off and the o2 sensor is right before the cat under the truck..

 

I find the Denso sensors have a longer tip on them and I use them in my LC header w/oissues. Get them from http://www.sparkplugs.com/

 

Technically speaking, you're right.. it's really only the mixture on that cylinder.
In pratical use, it works. The injectors are "batch fired" (fired all at once) and they're the same cc/min, so the mixture in one cylinder *should* be the mixture in the other three.
Course, if you had a bad plug, this could hose you a bit... But even with an 02 sensor in the collector a bad plug throws the mixture way off anyway - too far off for a narrowband to do anything other than measure "rich". I've run a narrowband sensor with the 02 in the header tube on a supercharged rig.. worked fine.

 

^^ Thanks for the explanation. Good to know. ^^