I have a 2005 350 with a turbonetics kit. I have a utec with a tuner wb. Nothing has changed on my car not any part, my boost, the outside temp, or any parameter on my utec. but now any time i start to put load on the car my afr goes super lean(>25). the car doesn't knock. the car pulls fine all is well. anyone ever had this problem?

 

Might be a bad sensor.

I would get it checked out at SGP regardless.

 

The car would have to be knocking at that A/F. It would at the very least display some major drivability issues. My bet is your wideband sensor went **** up.

 

ya seems like the wideband sensor has fouled out

 

The tuner wideband can be free air calibrated... try that.

 

+1

They should be free-air re-calibrated every six months or so...

Also, Bosch > VW for 02 sensors.

 

Someone at TurboXS told me that VW uses Bosch sensors as well - and the difference is purely marketing. (FWIW - I don't know - but I ordered the VW and I received a Bosch part from them).