I noticed after a few WOT passes that my scanmaster was reading 007 milivolts after I got off the throttle, it would stay low like this for a few seconds untill I slowed way down then the milivolts would go back to jumping around. Anyone have a possible explanation for this? I assume the lower the O2 readings the more rich, correct?

 

High is rich, low is lean. WOT is usually .880 or higher. Your O2s either could be dead, or you are lean enough that they can't read accurately, it may be in the low 14:1 or even 15s, it doesn't take much before they dont read accurately.

 

So what do you recommend I do? Replace the O2 sensors? Or is my car allright, becasue this only happens when coming off a WOT pass. Is there any way to check the O2 sensors?
Thanks for the reply
Tony

 

I think what you are describing is DFCO (deceleration fuel cut off). This only happens when you lift off the throttle right? Basically, the PCM shuts off the fuel injectors at high vaccum, high vehicle speed, and high RPM since fuel isn't needed. Once the conditions are met to reenable fuel it does so. This is perfectly normal behavior, and as long as the O2's oscillate rapidly when you see pulsewidths commanded for the injectors, you are fine. Or are you describing something else?

 

its normal. you just arent getting any exhaust readings because the tranny is pulling down the motor.

EDIT: or what buttercup said... either way its normal.

 

Thanks guys...........Buttercup- your right it anly happens when i let off the throttle.

 

Its a benefit to modern FI, little to no wasted gas on coast