Gas mileage dropping, worried something mechanical.

cddawgs said:

what could explain MPG dropping from 14.7 to 12.5. Its been gradual, I goose it occasionally but try to stay off the turbos, it's a daily, never sees dirt. Only had it new since august, 18. 5000 miles.

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Dirty air filter.... That's why it's gradual[emoji6]


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Tire pressure makes a difference. It was a noticeable drop in MPG when the cold winter temps caused a normal PSI reduction for a few psi (34psi to be exact). Once I pressured back up to 38, the MPG went back to normal.

I was averaging around 16 when I purchased around August. When winter really hit and got cold my mileage also took a major shit. My guess is that you'll start to see it recover when all the winter gas is used up.

cddawgs said:

what could explain MPG dropping from 14.7 to 12.5. Its been gradual, I goose it occasionally but try to stay off the turbos, it's a daily, never sees dirt. Only had it new since august, 18. 5000 miles.

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Pull and clean both MAP sensors. Without a catch can they WILL get covered in oil and mileage will degrade over time (mine did). Also do some calculations by hand, I found the built in meter to be quite optimistic.

My MPG's were dropping as a result of the IWE system not fully engage out of 4WD which is a documented TSB for Ford. Probably not related to what you're experiencing but my MPG's were dropping from 15-16 to 13-14 under same driving conditions.