Fuel economy dropping

[wchevron]

2021 JT with 55,000 miles. Added a 1.5" front leveling kit at 30,000 miles along with Falken Wildpeak 35's at the same time. Used my JScan to adjust the tire size. For quite a while was seeing 16-16.4 mpg average weekly. Combination of highway and city driving. Noticed the past couple of weeks I'm averaging low 14's. Tire pressure is 35 psi. Haven't changed anything on the truck or adding any weight.
Had it at the shop, was getting a check Electronic Stability light coming on. Maybe when they plugged in to pull up the codes it changed the tire size back to 33's?
Was going to plug the JScan back in to make sure the tire size didn't change but other than that can't think of why the drop off. Thoughts?

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[Gmac03]

Winter blend? ?

 

[kennyglm]

probably the winter blend gas . Certain times of year it has more ethanol in it . I can tell when they switch it over my mileage drops.

 

[DylanM]

+1 on the winter blend fuel. You also have colder, more dense air which requires more power to push the vehicle through at the same speed. Additionally, that more dense air getting into the engine also means more oxygen present, which in turn means the PCM will need to dump more fuel into the mix to keep the o2 sensor readings where they need to be.

 

[Hootbro]

Yeah, another vote for winter blended fuel kicking in. I get about 1.5 to 2 MPG drop every time it comes into rotation.

 

[kennyglm]

Yeah, another vote for winter blended fuel kicking in. I get about 1.5 to 2 MPG drop every time it comes into rotation.

yup i go from 15/16 to 14.5 / 15.5 for my average

 

[kevman65]

Even if you use ethanol free gas (yes it's still out there) you will find a drop in MPG's in the winter because of other additives that can rob power from the gas.

Even warm weather States will receive a winter blend with the possible exception of Hawaii.

 

[Billkowski]

Had my for two months, barely getting 14.5 mpg, maybe it will get better once it gets broken in.

 

[Maximus Gladius]

Maybe when they plugged in to pull up the codes it changed the tire size back to 33's?
Was going to plug the JScan back in to make sure the tire size didn't change but other than that can't think of why the drop off. Thoughts?

I’ll throw my hat in and say their diagnostic inspection changed the tire size. You were going to check it with your JScan, have you done that yet?

If you’ve noticed your mileage drop in the last couple weeks, it’s not winter fuel. We’ve had that since October.

 

[Lunentucker]

Winter blend. It's butane added, not more ethanol.

And more....


Why is winter fuel economy lower?
Cold weather affects your vehicle in more ways than you might expect:

• Engine and transmission friction increases in cold temperatures due to cold engine oil and other drive-line fluids.
• It takes longer for your engine to reach its most fuel-efficient temperature. This affects shorter trips more, since your car spends more of your trip at less-than-optimal temperatures.
• Heated seats, window defrosters, and heater fans use additional power.
• Warming up your vehicle before you start your trip lowers your fuel economy—idling gets 0 miles per gallon.
• Colder air is denser, increasing aerodynamic drag on your vehicle, especially at highway speeds.
• Tire pressure decreases in colder temperatures, increasing rolling resistance.
• Winter grades of gasoline can have slightly less energy per gallon than summer blends.
• Battery performance decreases in cold weather, making it harder for your alternator to keep your battery charged. This also affects the performance of the regenerative braking system on hybrids, plug-in hybrids, and electric vehicles.

 

[wchevron]

Thanks everyone. Will just confirm the tire size with the Jscan today or tomorrow, if it's still good, I'll chalk it up to winter fuel. Tried it this morning my but the app needed to be updated and I had no signal on my phone.
As far as it being the winter fuel, I only noticed the drop a few weeks ago. May have been going on longer and I just didn't know. I don't check the mpg to often.

 

[KevinC]

Even Florida gets winter blend fuel. I have noticed a decrease in MPG in just the last two weeks. I will also note that the wind has picked up and that also effects every Jeep brick going down the road.

KevinC

 

[MattKay]

But why do we have to have winter blend? Would it be so bad to have summer blend in the winter?

 

[DylanM]

But why do we have to have winter blend? Would it be so bad to have summer blend in the winter?

https://living.acg.aaa.com/blog/automotive/winter-blend-gas

 

[MattKay]

https://living.acg.aaa.com/blog/automotive/winter-blend-gas

Great quick read! Thanks!

I do however think it’s dumb that it is changed based on the month of the year and not the actual weather. But we live in an imperfect world. So it is what it is.

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