My car (165/maf) at idle shows O2 mv's in the 700's which would indicate a little rich. But my blm's are at 150 meaning its lean and having to add fuel. Why would the computer be adding fuel based on an O2 reading that's high? I've pretty much started to rely on the O2 reading rather than the blm's but it seem there's a contridiction here. Any thoughts?

 

O2 window values along with O2 modifiers for when in idle. In the tuning guide sticky, chap 5, under the '8746/'8063/'7747 ECM section. There is an article on fueling that covers this.

RBob.

 

Thanks RBob, that is great info. I've saved and printed it for digestion later but from what I saw, this is what I have been experiancing. I'll let you know how it works out.