If its flex fuel rated, there should be an actual ethanol sensor on the fuel line that reads ethanol content on the fly, the ECU then uses this information to adjust the fuel maps accordingly, and any fine tuning is done by o2 sensor readings.

 

If there's no ethanol sensor, it will work off the Long Term Fuel Trims and knock sensor feedback.

 

There is a sensor if it is flex fuel rated as mentioned. If it's not flex fuel rated and you put E-85 in it, you risk engine damage.
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So can I assume that the 5.0 coyote mustangs don't have this sensor?

 

Sure you can assume that. I have no idea. The 5.0 coyote in my 5.0 F150 however IS flex fuel and HAS the sensor as well as the injectors/fuel pump to support the increased fuel requirement and PCM strategy to make it all work.

What exactly is your question? This is a truck forum last time I checked.
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I've never heard a for sure answer as to why the mustang coyote is not flex fuel. Same injectors and same pump I believe.

 

Think it has to do with expected uses (agricultural) and possibly the increased power output of the mustang tipping the scales on the fuel systems ability to use E85. Government fleet contracts are another big reason for the F150 to use E85. I haven't crunched the numbers, but there is usually a 30-40hp spread between the Mustang and F150 5.0 ratings on any given generation, and that might just be enough for Ford to not want to run E85 on the Mustang without upping injector sizes.

For another piece of information, most Mustang tuners require the addition of 47lb injectors before you load an E85 tune, but I'm pretty sure that requirement applies to E85 F150 Coyote tunes too.

 

 

^^ Reiterating what the above poster along with another poster said. THERE IS NO ETHANOL CONTENT SENSOR ON ANY 5.0 LITER MUSTANG OR F150. Period. It uses a strategy with the wideband sensors and longterm fuel trims snapping back to zero after adjusting stoichiometric afr as it learns the ethanol content and estimates it based on fuel trims.