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why in stock ford files i saw the stoich AFR is 14.08 ?
if i changed to 14.7 or 14.68 it will be danger ?
It's possibly a stoich setting to suit gasoline with a small ethanol content. If you change the stoich setting it will have a major effect on the AFR you achieve so you do need to be mindful of this. It 'should' represent the true stoich value of the fuel you're running.
14.08 stoich AFR is probably a safe guess for pump gas in the US. I've got some datalogs showing about 8% ethanol (14.2 stoich AFR) for California pump gas, as measured by that GM / Continental flex fuel sensor that is pretty common.
If you have a map that already runs well with that 14.08 value and change it to 14.7 without any other changes, the ECU should inject less fuel and the engine might run slightly leaner.