I think the reading's supposed to be around .6 or so, but am not positive off-hand.
The reading should NOT move around too much when under steady load. The car will run VERY lean when backed off the throttle (infact, 0 fuel is being injected, while rpms drop at 0 load), so if that's what you're implying then all is good. MPG meter will give you a good idea, and it's very precise, but not accurate at all.
The mpg meter is NOT affected by the AFM signal, once the flap is all the way open (this happens around 2700rpm at full load), only throttle position, and crank angle/speed matter after that point. If you make the car run lean through the spring tension alone (and without drilling holes), you may loose a bit of power. I'd seriously look into adjusting the setting at DME.
I'm quite certain that the tighter you make the AFM, the better economy the gauge will show, but the less power you'll make (which may force to apply more gas, loosing economy). Driving technique makes all the difference.
Anyway, have you messed with the DME? If not, 3%leaner with 0 timing change could be the ticket for ya. Let me know what you think.
Ahmet
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