O2 sensors on 818R and stock ECU?

[C.Plavan]

Please educate me on the use of O2 sensors.

What I think I know is that the manifold (front) O2 sensor should be used for A/F readings correct?

The rear O2 sensor is optional since I do not have any cats correct? This spot you can possibly use a wideband sensor correct?

Again, this is for a race car 818R without any emission stuff-

FYI- I have a V3 Cobb Accessport.

[RM1SepEx]

your exhaust is so short that the second sensor will have issues due to backwash of ambient air (from my friend with the Dynocom 150000 dyno in his garage) I'm not sure what we should do, I'm also using the Cobb V3 and I'm not sure if I should even install the O2 senser bung after my cat and before my muffler... Our entire exhaust systems are less than 3 feet long!

[waruaki]

On advice from someone I consider knowledgeable (certainly more knowledgeable about Subaru tuning than myself) suggested that during my wire diet I remove the rear O2 loom as I also do not run cats on my build. I now run only the front sensor for the air fuel data for the ecm. I had to have several permanent CEL codes deleted TGV and the rear O2 to get the motor to run smoothly (I believe the motor was in limp mode). Motor now runs great, no check engine light but will need to be put on a dyno and get a tailored map when the body work is finished to maximize performance.

[C.Plavan]

Thanks for the info Guys.

[mekohler]

I have read different things, the best I could determine is if you are running a 32bit engine computer the rear O2 does functions that are needed to run properly, the 16bit is for emissions only. I would welcome a difinitive answer as I am running a 32bit EMS.