Switched off O2 feedback WOW

[NixRX7]

I have been having constant probs the last few months with the car not idleing very well and generally not being "right" if you know what i mean.

I was looking through some old posts and came across one about the Apexi not needing the input from the O2 sensor, so as i have never ever touched the settings in the PFC i got the instruction book out and found out how to switch it off ( hope i got the right one it was under ETC/ ORIGINAL FUNCTION SETTING)

Anyway, what a difference its made, the car no longer just ticksover, it bloody PURRRRRRSSSSSS and it drives completley differently, much much smoother, the only concern i have is that before the car would never boost above 0.8 usually it would only ever get to 0.7, no matter what the temperature was outside or any other factor it would never ever boost above 0.8.

Now however its boosting to 0.93 with an inection duty level of 86% the car is bloody flying, just to check i turned O2 back on and it went back to its normal way of running i.e a bit rough and not idleing

What i want to know is WHY, why would switching off O2 feedback have such a dramatic effect ?
The only thing i can think of is that maybe the guy i got the car off must have originally got it mapped to run at 0.9 when he had it set up by WGT, and when i got it off him a few months later it had developed this fault and has never been running as intended.

Still cant understand why switching O2 off on the Apexi would effect boost tho :xconfused

And if its now going to running at 0.9 boost i had better get me arse in gear and get the WI fitted.

And get the O2 sensor changed and see what happens with a new sensor and O2 switched back on.

Nick