Fitting an additional O2 bung on Stock header?
 

I've been given an Innovate LC1 which I plan on fitting to the car to enable street tuning. There doesn't seem to be a good long term solution to disabling the secondary O2 with opensource so I'd rather leave that be.

Have the factory header with Invidia over pipe, catted front pipe and Q300 rear section. Obviously the best place to put it would be before the cat in the factory header but haven't seen it without the head shielding so not sure if there is even room for another O2 bung. Has anyone done this? Photos of location would be awesome if they have!

If there is no room, I'd most likely have the bung put in the front pipe before the cat as getting the over pipe squeezed in is hard enough as it is, without having an o2 sensor attached.

I have no plans of changing headers FWIW but I will need the workshop to clean up the flanges between over pipe and front pipe. The fitment isn't perfect and I notice some condensation from the exhaust leaking around that joint. Guessing if its enough to leak condensation, its not ideal.

I wouldn't bother. If your street tuning an NA the reading from the factory O2 sensor is good enough.

I run an LC1 in place of the second O2 sensor. Easy on catless headers/dump pipe. It's only useful for tuning richer mixtures on a car with FI.

I was under the impression that the OEM sensor was decent but even on N/A not a good enough substitute, at least for tuning purposes? I'm staying N/A but want to refine my 98 and E85 maps and dyno time is difficult.

I'd originally thought of using the secondary spot with the LC1 but mad_sb seems to have had issues with brzedit disabling it, I'm using ecuflash which I suspect will be the same. Everyone else appears to be using ecutek?

The second 02 sensor is a bit more wideband than the primary 02 sensor.
on an oft you can read both the prmary and secondary 02 values.

they tend to be a bit different due either side of stock cat.

if you have tactrix you could also read the second 02 as its just a ram address, unfortunatly i dont know what it is, @Td-d or @ztan may know the ram address for the second 02 sensor on an A01G rom.

You coud then calibrate the stock second 02 reading against the tuners wideband, sure it would be wideband enough for NA tuning.

if you found that ram address then their is no reason you could not do what the oft guys did and repace second o2 with a true wideband and a controller to map values back to levels acceptable to ecu then read the ram address and scale the values appropiatly.

http://www.ft86club.com/forums/showthread.php?t=61724

I'd read elsewhere here that the secondary sensor is a narrowband while the primary is a "Denso limiting-current type wideband sensor".

That said, maybe I am wasting my time with a 3rd bung for the LC-1.

That's true. However the primary O2 isn't what people refer to as either wide or narrow band. It'd kind of in the middle. I find it's within 0.5 of my LC1 and it only reads to 12:1 on the stock rom. You can change the O2 scaling to help it read a little richer. You don't want to go richer than 12:1 NA anyway...

The primary O2 sensor is definitely good enough to tune with. I only got my LC1 so I could have a wideband gauge on the dash. I still tune using the standard O2 sensor output.

If you want to use the LC1 in place of the second O2 sensor just feed the 0-1V output into the factory wiring. You just have to turn off the O2 heater CEL in the ROM.