Originally Posted by RoadKillDMD
You can use the stock location rear o2 sensor bung to run your wideband, but you can't utilize it with the stock harness to monitor it through your ECU. The stock rear o2 sensor is there as a part of the open loop/closed loop fueling system these cars have to monitor the catalytic converters effeciency. You would need a tune to delete the code that would result from removing said o2 sensor.
A wideband gauge has a kit that comes with another bung that you weld (or get welded) into your DP. You mount it in your cabin to monitor AFRs as you're driving. You can't use your stock o2 to accurately monitor real time AFRs.
If I got a wideband and the rear 02 is going out then wouldn't this still effect my tune? I know that on the newer WRXs the rear effects closed loop. Also i am curious as to why you cant use the stock sensor to monitor is you are catless. I understand its not as accurate as a wideband but shouldn't it do the job for just monitoring?
I guess what I am getting at is that if I get a wideband and still have to replace the stock 02 that may be too much investment right now and I may just replace the stock 02.
Also I have been told it would be possible to hit 18 A/F under boost on E85 and not knock. So it may not be the 02 after all. Uhg been chasing this problem and throwing money at it for over a month now. I do need to get it hooked up to a wideband though to see what is really going on. I just wish there was a way to get a wideband without having to replace the stock 02 if its bad as well. I thought I read somewhere that you can trick the wideband into working with the stock voltage but I have no idea how that works.