MPG fall off recently - Cold Weather related?

[Mark S.]

We've had two weeks of cold temps here in the STL area, culminating in today's frigid temps.

This was right before I filled the tank. Note the number of miles on this tank, and the computer's calculated MPG. That turned out to be optimistic: actual MPG was 23.3. That's more than three MPG lower than the car's lifetime average of 26.7. Winter's here!

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[max the dog]

The MPG on my '21 Outer Banks is starting to fall off and I don't know why...

I always kept an eye on my MPG (typically around 29 - 30mpg) but I recently started a new job with a 75 mile one-way commute. Ouch, I know. 90% of the commute is highway. Southern NH to far west of Boston, so unless there is an back up or something, I'm typically able to do 65 - 80MPH most of the way. During the first month of the new job I was getting right at 30mpg. I have to fill up every two days (and trust me, gas is way cheaper in NH vs Mass). But suddenly my MPG dropped off to 26mpg. And it's not just the MPG - the 'Miles to Empty' gage also showed a decrease. Normally when I'd refill it would be about 440 miles to empty. Now it calculates 410 miles to empty (after a refill).

I thought maybe I'd gotten a bad tank of gas (I did stop at a new station). But after 4 refills at my normal Mobil station the MPG has not returned. The only thing I can think of that would cause this is that the temps have consistently been below freezing recently. Would the cold temp affect MPG that much?

Background notes:
New tires & brakes just before I started the new gig.
When I started the job I had 40k miles on the Bronco. The MPG fall off started around 50k miles.

Thoughts?

You are pushing a box. Winter blend does not help With my Bad Lands around town, if gentle, I get 30mpg. Once I go above 60 I lose 3 mpg.

 

[Mwittke5857]

The MPG on my '21 Outer Banks is starting to fall off and I don't know why...

I always kept an eye on my MPG (typically around 29 - 30mpg) but I recently started a new job with a 75 mile one-way commute. Ouch, I know. 90% of the commute is highway. Southern NH to far west of Boston, so unless there is an back up or something, I'm typically able to do 65 - 80MPH most of the way. During the first month of the new job I was getting right at 30mpg. I have to fill up every two days (and trust me, gas is way cheaper in NH vs Mass). But suddenly my MPG dropped off to 26mpg. And it's not just the MPG - the 'Miles to Empty' gage also showed a decrease. Normally when I'd refill it would be about 440 miles to empty. Now it calculates 410 miles to empty (after a refill).

I thought maybe I'd gotten a bad tank of gas (I did stop at a new station). But after 4 refills at my normal Mobil station the MPG has not returned. The only thing I can think of that would cause this is that the temps have consistently been below freezing recently. Would the cold temp affect MPG that much?

Background notes:
New tires & brakes just before I started the new gig.
When I started the job I had 40k miles on the Bronco. The MPG fall off started around 50k miles.

Thoughts?

be interested to know what grade of gasoline you use. I always use premium and get about 29-30 with mostly highway miles

 

[Mark S.]

be interested to know what grade of gasoline you use. I always use premium and get about 29-30 with mostly highway miles

Try a few tanks of regular. I'm guessing there won't be any difference.

 

[Major Kong]

heat blower fan on high
wiper motor
window defroster
heated side view mirrors
heated seats
heated steering wheel
fog lights
extended time driving in dark. more lighting

 

[BLUEOVALRACER]

Did they provide any data, or just opinion? Ford sells spark plugs through its Motorcraft division, giving it a very good reason to suggest shorter replacement times, yet it doesn't. Ford's recommendations are based on data.

Just opinion and i think some of them had been tuned!!Although a friend of mine had a bone stock F-150 with the 3.5 Eco Boost and he said it was running crappy IIRC it didn't have a CEL on Auto zone told him probably an Oxygen Sensor!!He didn't think it was that he thought it was the spark plugs changed them and it was back to running fine!! IIRC he said this happened around the 40-50,000 mile mark!

 

[Mark S.]

Just opinion and i think some of them had been tuned!!

Some tune vendors suggest different (slightly hotter/colder) spark plugs to accommodate the different engine operating parameters. I've inspected the plugs on all of our EcoBoost-equipped cars over the past decade or so; Ford's service interval seems correct to me based on my own personal experience.

 

[Bronco Blue]

Mine has gone down too like it did last winter. It’s with having the heat on full blast and the heated steering wheel and seats, it uses a lot of gas. Also using the remote start drains it too.

I should also point out because I have the issue with mine is that a lot of interstate driving reduces the mpgs, for me at least. Idk why, I’m assuming it’s because it’s a box on wheels so that greater airflow is making the car work harder to cut through it but again, idk. Never had that problem before (the Escape I had gained mpg on the interstate), so that’s my only guess as to why I lose mpg on the interstate going 75 mph.

 

[Scapino]

Hi All:
Thanks for the responses & feedback. Glad to know the MPG drop off is normal. I always keep an eye on my MPG as it can be an early indicator to something else going wrong. Especially interested in the comment about possibly needing new plugs. I might do that.

And yes, I do need to check my tire pressure (recently got an oil change but noticed that they didn't check my pressures). Side note: On the way home last week my right rear TMPS went inop for about 10 miles. Bronco threw a Flat Tire warning but the tire pressure was showing XXXX. Then strangely, it came back on...

To answer some of the questions: Yes, this is the first full year my Bronco has seen snow. But, when I was in Chicago I drove a Ford Exp Sport Track for 15 years (for over 200k miles) and never noticed the MPG difference in winters. Granted, completely different vehicle with a different engine...

And yes, I should slow down. But the limit on part of the commute is 70mph. And I like to be(at least) 10 above the limit.

 

[Scapino]

EDIT: Corrected a slight error. Denser air makes more power because there are more oxygen molecules in a given volume.

You might be interested to know: When I was in the Air Force (a lifetime ago), the B52 (when fully loaded) needed water injection into the engines on takeoff for greater thrust. We didn't need to do that in the winter because the air was naturally more dense (and obviously, the water would freeze which would be a bad thing).

 

[Scapino]

be interested to know what grade of gasoline you use. I always use premium and get about 29-30 with mostly highway miles

I just use the recommended low grade 85.

 

[Mark S.]

You might be interested to know: When I was in the Air Force (a lifetime ago), the B52 (when fully loaded) needed water injection into the engines on takeoff for greater thrust. We didn't need to do that in the winter because the air was naturally more dense (and obviously, the water would freeze which would be a bad thing).

Ahhh, memories. I spent many a night heating water at Minot AFB, ND. We were on satellite alert from Ellsworth AFB, SD. Our EC-135A/G models were equipped with J57 engines which, as you note, required water injection to achieve full takeoff thrust. Below 20F the cold, dense air was enough, but above 20F we would inject nearly 700 gallons of water into the four engines for two minutes during takeoff and initial climb. So why was I heating water? Between 20F and 40F cold water would freeze when pumped into the low pressure engine intake. The water had to be at least 60F. The water tank in the jet was equipped with heating elements, which we would turn on every so often to keep the water hot enough. We shared the duty with our crew chief (maintenance personnel) so they didn't have to spend all night out at the jet keeping the water heated. You can read more about it here if you're interested.

Fun times!

 

[Mark S.]

I just use the recommended low grade 85.

You shouldn't use fuel with lower octane than 87. You can get away with 85 in normally aspirated engines at altitude because you get less air in the engine. The turbocharger in your engine pressurizes the air before it goes to the engine, so the amount of air is essentially the same at most altitudes accessible in the USA. Bottom line is you need to stick with 87 octane.

 

[Scapino]

You shouldn't use fuel with lower octane than 87.

Sorry, I meant 87. I think 85 is only available in the mountains as you suggested.

 

[Ford Motor Company]

The MPG on my '21 Outer Banks is starting to fall off and I don't know why...

I always kept an eye on my MPG (typically around 29 - 30mpg) but I recently started a new job with a 75 mile one-way commute. Ouch, I know. 90% of the commute is highway. Southern NH to far west of Boston, so unless there is an back up or something, I'm typically able to do 65 - 80MPH most of the way. During the first month of the new job I was getting right at 30mpg. I have to fill up every two days (and trust me, gas is way cheaper in NH vs Mass). But suddenly my MPG dropped off to 26mpg. And it's not just the MPG - the 'Miles to Empty' gage also showed a decrease. Normally when I'd refill it would be about 440 miles to empty. Now it calculates 410 miles to empty (after a refill).

I thought maybe I'd gotten a bad tank of gas (I did stop at a new station). But after 4 refills at my normal Mobil station the MPG has not returned. The only thing I can think of that would cause this is that the temps have consistently been below freezing recently. Would the cold temp affect MPG that much?

Background notes:
New tires & brakes just before I started the new gig.
When I started the job I had 40k miles on the Bronco. The MPG fall off started around 50k miles.

Thoughts?

Hi there! Would you send us a private message with your VIN and dealership name and location? I’d like to look into this concern on my end.  

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