Months back I hooked up a multitester to my o2 sensor to read it's output voltage and gague whether or not my car was running rich or lean based on its readings, everything came out reading normal, and my SES light has never shown a rich condition, however today I went to a dyno and when he hit WOT the car went really rich, ran 15:1 at 2000rpm then dropped to 10:1 around 4000rpm before it came back up to 11:1 at 5000rpm. My fuel pressure is at 12psi, set by the factory I've never changed it, and I've got a Jet chip in there, anyone have any ideas on why my car is riching out so much? Shouldn't the ECM see that in the o2 outputs and be reducing the amount of fuel its sending into the motor? Thanks.

 

This is not surprising. Several stock L03 dynos I've seen produce the same results AFR wise.

The factory sends them out rich to protect the CAT and to limit the possiblity of detonation.

The O2 is NOT used by the ECM at WOT. It won't correct a rich condition.

 

my car is the same way, what can i do to fix it

 

it looks like you need to data log and burn a chip. the area that needs tuning is PE(power enrichment).