New O2 Sensor, Now Car Pops

[Robo's]

I put a new O2 sensor in, now the car pops occasionally on gear changes. It also popped when i turned the O2 sensor off from the PFC but now i switched it back on and the car occasionally pops on gear changes. I know this is rich fuel but why is it so with the new sensor?

[R31Nismoid]

The o2 only works on low throttle/cruise or something if memory serves me correct... so are you under throttle and changing and its popping?

Mine pops (i can make it do it) on light throttle even with O2's (RB26), tune is fine though as im getting 400km's around town and 600 on the fwy

[Robo's]

Yeah medium throttle it pops, not all the time but every now and then where before it never popped once. I will connect the Wideband on it and check the AFR's maybe with the O2 sensor working properly, they might have changed