So my EJ swap is on the road (thanks to the tireless efforts of dr.suberdave), but with no o2 sensor at the moment.  I got subie101's headers and got the rest of the exhaust done at proexhaust, but they didnt put a bung in for the o2 sensor, and obviously im getting a CEL.  My question is would it be better/smarter/more economical to get the bung and sensor put in, or leave it sensor-less and potentially correct it via a retune? Thanks in advance, I appreciate it guys.

I also have a header from subie101, when I built my mid pipe assembly I used a universal catalytic converter with a integral o2 sensor bung and then an additional one after the cat.

 

I just drilled a 3/4" hole and welded the o2 bung on the pipe. I was able to pick up a weld in bung with a plug from amazon for $10 link [the thread pitch and diameter is the same as OE replacement sensors for a 97 Legacy]

 

it would probably be easier/better/smarter to just run the o2 sensor. plus no CEL would be awesome... (my CEL is not attributed to the oxygen sensors)

 

Ben

Well, no N/A EJ ECU is re-tuneable.....so unless you're running a standalone, that's not an option.

 

 

Assuming this is an up-stream 02 Sensor (it helps to know what year, model, size, etc. EJ you have  ), it is used to constantly adjust fuel trims. Yes, install it.

Well, no N/A EJ ECU is re-tuneable.....so unless you're running a standalone, that's not an option.

 

Well, I beg to differ. 

 

Anyway, yes weld a bung on and put a sensor in.  For anything other than a pure race car it makes a whole lot of sense.