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st-evo-9*corn fed-8urvet* · 08-04-2008, 04:03 PM

oh ya crystal ass clear!!!

so ya after my tune my highest vacuum is 10-9 in numerical value which yields me about 65mph at on cold nights or cold weather in general

but this is only because of my tuning. a stock evo would probably hit 50-60mph

and if u look at just about every stock tune out there

there fuel areas read at 14.7 in the idle and cruising cells in relation to engine load and rpm.

this is because 14.7 is the air/fuel ratio that is perfect for best emissions....all cars i have seen that have installed a wideband o2 air/fuel ratio monitoring system will read at 14.7 no matter where u are in the cruising area of ur stock tuned factory map

so in essence u arent really gonna yield to much better gas milage by letting off the throttle because the car is always gonna compensate the afr and make it 14.7:1 which most cars to get the best fuel efficiency there afr needs to be at 15.8:1 to 16.1:1 on petrol based fuels.

08-04-2008, 04:03 PM	#20
st-evo-9corn fed-8urvet Senior Member Join Date: Jul 2008 Posts: 501 Tweet	oh ya crystal ass clear!!! so ya after my tune my highest vacuum is 10-9 in numerical value which yields me about 65mph at on cold nights or cold weather in general but this is only because of my tuning. a stock evo would probably hit 50-60mph and if u look at just about every stock tune out there there fuel areas read at 14.7 in the idle and cruising cells in relation to engine load and rpm. this is because 14.7 is the air/fuel ratio that is perfect for best emissions....all cars i have seen that have installed a wideband o2 air/fuel ratio monitoring system will read at 14.7 no matter where u are in the cruising area of ur stock tuned factory map so in essence u arent really gonna yield to much better gas milage by letting off the throttle because the car is always gonna compensate the afr and make it 14.7:1 which most cars to get the best fuel efficiency there afr needs to be at 15.8:1 to 16.1:1 on petrol based fuels.