cyberd0rk

Bought the catted Y from Texas Speed and need to add o2 bungs. Currently I'm tuned out for the rear o2's so I'm hoping I won't run into any trouble, BUT if I have to revert the tuning for emissions testing will the location of the o2 in relation to the cat matter? I would hate to drill a hole in the wrong location and have a forever malfunctioning sensor. This is not a thread of alternatives to bypassing or tricking the sensors, I know I have plenty of options. What I want to discuss is actual reasons of where and why (if any) the bungs are located.

farmington

iTrader: (14)

I would try to replicate the factory distance behind the convertor and the same clocking.

nine8ss

iTrader: (5)

The factory location of the rear o2 is just after the converter flange. This location is chosen because the 2nd o2 just monitors the effectiveness of the cats. Too far from the cats and the efficiency will drop.

cyberd0rk

I'm aiming for 6"-8" behind each cat. Unfortunately I never owned a stock piece to measure off of. I was concerned too far or too near would create some kind of condition where the plug was off temperature or something.