2014 Explorer Sport eco HORRIBLE gas mileage even with new plugs

[jryanbass]

Hi everyone! I just bought a new to me 2014 Explorer Sport Ecoboost 4x4. It has 81k miles on it. 2 days after I got it I noticed the gas mileage was terrible. 10-11mpg. Took it into the shop and got all new plugs and the fuel system cleaned, and it was better for a few days, averaging 17mpg in the city. Now a week later its idling bad again and averaging 13mpg. Any ideas what is wrong?! I love my car but this is awful.

 

[peterk9]

Welcome to the Forum.
Does drive okay? No misfires, hesitation etc? When you say you had the fuel system cleaned, did that include the throttle body? I've noticed a very slight mpg improvement using 91 octane but definitely not enough to offset the cost of it.

Peter

 

[Odrapnew]

Pull codes, sounds like a sensor is bad/dirty(oxygen sensor or MAF sensor come to mind)

 

[jryanbass]

He cleaned them both. New air filter and a commercial cleaner ran through the fuel system as well. It drives fine, no hesitation, but when I crank it and its idling it feels like it is going to die. He did say it was one of the dirtiest cars he'd seen in a while.

 

[blwnsmoke]

Bad throttle body? Injector not functioning properly?

 

[KayGee]

What was original diagnosis that led to new plugs and the fuel system cleaning?

Did you take it back to shop after it started running poorly again and inform them it was running the same as when you brought it in originally? If so, what did they say?

 

[jryanbass]

They said the plugs were slightly out of gap and it was just filthy. I haven't taken it back yet, I plan on doing that Monday.