I can tell you Roush had the rear 02 sensors turned on in my tune. Because of their C.A.R.B. certification, they would have to be operational.

 

wouldnt it be the same as ford certification? i know the f150 ran good without the roush and no rear o2's?

 

I'm know Ford doesn't turn off the rear 02 sensors, but there are parameters in the PCM to do that. If you turned them off, you must have had a custom tune to achieve that. If that's the case, and you've been running no rear 02s, your rear 02 sensors could be in bad shape. If you've removed them, the truck might be going into a default or limp mode without them.

 

Troyer doesn't either, I tried to get him to turn off mine and he said no. Get yourself a set of O2 sims or MIL eliminators to hold you over until you get a tune with the rears turned off.