Major Tank Mileage Estimate Drop in Car Wash

[Darry_Lavid]

Not sure if this is the first time I’ve seen this happen, but went through the car wash this AM, and watched the tank estimate drop from 410 to 380 during the duration of the wash (in neutral, mpg estimate never). Ended up settling at 380 after exiting…

Anyone ever see this drastic of a drop in a 30 second wash / know what would cause it?

I have a 2022 Lariat 5.0 for reference…

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[ds635h]

Happen to be running E85 this tank? I’ve watched my miles to empty plummet when idling with E85

 

[My 2ND Ford]

If this was after a fill up and you reset your mpg, they always drop while idling.

 

[Darry_Lavid]

Happen to be running E85 this tank? I’ve watched my miles to empty plummet when idling with E85

87 - filled up about a week ago

 

[Darry_Lavid]

If this was after a fill up and you reset your mpg, they always drop while idling.

Filled up about a week ago. Haven’t reset in over a month.

 

[My 2ND Ford]

Filled up about a week ago. Haven’t reset in over a month.

Other than suggesting that the mpg computer had a brain fart, I have nothing else. I don't remember ever seeing that large a drop in that short a time. Good luck.

 

[powerboatr]

How long was car wash??

 

[Darry_Lavid]

How long was car wash??

No longer than 1 minute - machine wash

 

[Pcabe5]

I've noticed that while idling or remote started. I would say it's normal as your MPG is going down so your miles to empty will decrease.

A less than a minute car wash??? More likely about 5 minutes or so. Don't think I've ever been in an automatic carwash that was less than a minute.

 

[adyaro77]

Not sure if this is the first time I’ve seen this happen, but went through the car wash this AM, and watched the tank estimate drop from 410 to 380 during the duration of the wash (in neutral, mpg estimate never). Ended up settling at 380 after exiting…

Anyone ever see this drastic of a drop in a 30 second wash / know what would cause it?

I have a 2022 Lariat 5.0 for reference…

Interesting to hear this. I will be getting great gas mileage with my 5.0 and if I sit and idles it drop a great deal. Was at dealership getting the 360 recalubrated. Dropped it off with 20 mpg avg and picked it up saying 11. Technician said he was sitting in it and letting it idle while pulling in and out of parking spots. Not concerned because I'm constantly getting more than 19.5 miles per gallon on avg.

 

[Darry_Lavid]

Interesting to hear this. I will be getting great gas mileage with my 5.0 and if I sit and idles it drop a great deal. Was at dealership getting the 360 recalubrated. Dropped it off with 20 mpg avg and picked it up saying 11. Technician said he was sitting in it and letting it idle while pulling in and out of parking spots. Not concerned because I'm constantly getting more than 19.5 miles per gallon on avg.

Was the first time I noticed it. There have been times that I’ve sat in the truck an hour or so in park and the mileage barely changed. Hopefully just a one off…

 

[Pedaldude]

The remaining mileage is an extrapolation of your driving habits.

If you’re idling a lot it will assume that you’re going to be idling a lot and will adjust accordingly. If you’re driving on the highway, the estimated mileage remaining will start to increase because it assumes you’re going to continue driving on the highway.

Anytime you change states it will adjust. You get zero miles per gallon while idling, so any change in that behavior will increase/decrease most dramatically.

The major difference is that you’re more likely to notice any changes when you’re idling getting 0MPG than when you’re driving 65MPH on the highway getting 20MPG.

In my truck at least, the eco behavior is based on the key on/off and not the trip meter unless you’re selecting the specific page in the myview setting where the trip meter info is displayed.

Who knows what the inputs are for the miles to empty in the gen14 trucks are but they’re least accurate with a full tank because who knows what happens in the next 400 miles or X hours of engine idling. Even towards the end of a tank the miles to empty is more accurate for the trip meter on my 2001 Lincoln than my 2021 F-150.

This is all pretty standard and I wouldn’t worry about it at all. Degradation of fuel mileage is something to pay attention to but I would only take notice of hand calculated MPG and not anything that the trip meter is guessing.

 

[Murrk847]

This must have been a bug. My truck did the same thing yesterday. I filled up and drove about 60 miles. getting around 21 mpg. DTE was around 410. Started my truck up a few hours later and my fuel gauge dropped fast and my DTE dropped like 35 miles. I got out and looked under my truck to make sure i didn't have a fuel line leaking lol.

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