Big mileage drop

[nadalin]

I hit 8500 miles and my overall mileage went from around 23.x to 18.x no idea what is going on, took it to ford dealer and they had it a week and could not find anything wrong, anyone seen this behavior yet ?

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[Snakebitten]

What part of the country are you in?
Weather change? Winter blend fuel?

There's factors that might not be the truck itself. Did it feel like it wasn't performing the same as it had previously?

 

[nadalin]

What part of the country are you in?
Weather change? Winter blend fuel?

There's factors that might not be the truck itself. Did it feel like it wasn't performing the same as it had previously?

Its not performing as it did for sure, weather was the same during the mileage drop, I live in Washington State so moderate temps, driving habits have not changed

 

[Oxford_Powerboost]

Its not performing as it did for sure, weather was the same during the mileage drop, I live in Washington State so moderate temps, driving habits have not changed

In what way has the performance changed?

 

[nadalin]

In what way has the performance changed?

Slugish, less electric driving, more gas pedal to needed to keep up in traffic

 

[dmac]

See my post here. Colder temps seem to have a big impact on mileage:

https://www.f150gen14.com/forum/thr...getting-with-your-powerboost.1373/post-111247

 

[nadalin]

See my post here. Colder temps seem to have a big impact on mileage:

https://www.f150gen14.com/forum/thr...getting-with-your-powerboost.1373/post-111247

But temps have been pretty consistent here during the 5mpg drop

 

[JerseyGlock]

Bad gas?

 

[allJUMPstyle]

Possible water in the fuel?

 

[Pedaldude]

Winter blend fuel uses more ethanol than summer blend and while some stations add a nominal amount, others are known to mix in the maximum allowed. Especially when oil prices are high.

Ethanol has a much lower energy density than gasoline and when combined with gasoline, there's a net decrease in total energy. Meaning that the combined energy of the blended fuel is less than that in the two components before they're added to each other.

Another possibility is a bad O2 sensor, which can result in extra fuel injected. It won't trip any codes unless it's really bad but hopefully the dealer ruled that out, since it can be checked with even a cheap OBD computer.

 

[nadalin]

Possible water in the fuel?

Don't think so as I have been trough about 5 tanks from different stations and still a 5 mpg drop

 

[nadalin]

This sure sounds like a change in the software when it reaches a certain millage, past the break-in

 

[Snakebitten]

Interesting. I've never heard of a time triggere tune change. At least not on a Ford Ecoboost.
It's actually more common for these trucks to gradually improve in fuel mileage as they break wear in, all things being equal.

(Fuel/Weather/suspension-tires/etc)

 

[Zyvin]

“Build back better” gas.

 

[nadalin]

Interesting. I've never heard of a time triggere tune change. At least not on a Ford Ecoboost.
It's actually more common for these trucks to gradually improve in fuel mileage as they break wear in, all things being equal.

(Fuel/Weather/suspension-tires/etc)

There is a definite change in tune that are mileage driven, but its usually to get better performance not worse as limits were changed in my Focus RS which is also an ecoboost when it reached the end of the break-in

 

[playjack]

Tire pressure check?

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