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I'm wondering while at idle is it normal for the air fuel ratio to fluctuate between 14.4 and 15? It seems as if when it drops to 14.4 the idle will also act a little funny while I'm cruising it also fluctuates between those same number but drives fine I know 14.7 is ideal just wondering if this range is normal conditions? Also it has been cold like 3 to 20 degrees for over a week and is now going back up to around the 50's didn't know if this could play a factor as well?
 

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Your cruising AF ratio will always be fairly lean, same with idle. As long as it fattens up under boost and wide open throttle there's nothing to worry about.

At cruising RPM, as well as idle, your engine will be most efficient in a lean state and is this not detrimental as cylinder temps are not elevated as they are under boost.

The ECU will compensate for air temperature variances.
 

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I have a Stratified OTS 93 octane tune and live in Massachusetts. Driving non-WOT my AFR seems to fluctuate between 14.55 and 15.10 on average. 14.70 seems to be the median at normal cruise; but it definitely does not stay right at this value. I find that my AFR fluctuates up and down "around" this value.

I am not concerned.
 

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As long as when you go wide open throttle it hovers below 11.5-12 then you're fine. Now, if it's abnormally rich and hovers at like 9-10 (mine is typically 10.5 which is rich-ish but fine) then you should have that adjusted...but lean is much more bad for the car than rich.
 
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