Cause for significant drop in mileage in 2.7 L?

[JonathanDuong]

I've had my 2.7L for about two months and have made 3 road trips with it, just crossed 4000 miles last night.

First and second road trip I got 17-18MPG on the highway.

Just drove from Texas to Colorado, about 900 miles, and barely got over 13 MPG the entire way (haven't even gotten to mountains yet.) I tried both Eco and Normal mode and didn't seem to help.

Any ideas what could be choking my mileage? All gauges seem to indicate everything is normal. Also, there were fewer people/weight on this road trip than the other two.

I am a firm believer that cruise control uses more fuel as your engine is constantly fighting to maintain that speed. It means more acceleration when not necessarily needed. I'd rather feather throttle at 75 then have it drop to 71 and back to 75. My feet holds a constant light pressure to where my guage would float in the 20MPG range. Though overall average is still 15.6 but it's just mainly a vehicle I use to go to work so far. No trips yet.

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[Jdc]

I am a firm believer that cruise control uses more fuel as your engine is constantly fighting to maintain that speed. It means more acceleration when not necessarily needed. I'd rather feather throttle at 75 then have it drop to 71 and back to 75. My feet holds a constant light pressure to where my guage would float in the 20MPG range. Though overall average is still 15.6 but it's just mainly a vehicle I use to go to work so far. No trips yet.

https://www.motortrend.com/features/does-cruise-control-save-gas/

 

[WuNgUn]

Absolutely correct, and the new Bronco has a fuel system that CAN deliver 50% more fuel than needed partially for this exact reason. E-85 is drastically cheaper than 93 octane though (at least where I'm at) over $1.55 cheaper per gallon, so that needs to be taken into consideration.

Funny thing is when I run 50/50 E-85, a full tank only gets me 225miles. But those miles are RADICAL with the extra power available from high octane and tuner.

Alcohol doesn't have the BTU's of gasoline... So you need to burn 1/3 more of it than gasoline for the same power. Yeah, mileage is gonna suck ass.... But I've seen tuned turbo cars on e85 make ridiculous power

 

[Realtor]

https://www.motortrend.com/features/does-cruise-control-save-gas/

The facts. A good read, thank you.

Cruise saves for most drivers, especially with constant grades.

 

[Gtrekker]

Nope, less weight this time.

Thought about wind, but it wasn't significantly windy yesterday as it has been earlier in the week.

You were heading north so you were going up hill....

 

[da_jokker]

I am a firm believer that cruise control uses more fuel as your engine is constantly fighting to maintain that speed. It means more acceleration when not necessarily needed. I'd rather feather throttle at 75 then have it drop to 71 and back to 75. My feet holds a constant light pressure to where my guage would float in the 20MPG range. Though overall average is still 15.6 but it's just mainly a vehicle I use to go to work so far. No trips yet.

I could see this being the case if there was a lot of hills where the cruise control was getting on the throttle unnecessarily. But a relatively flat ground, cruise control will guaranteed save you gas mileage assuming you don't have it set at 85

The reality is that as steady as We may think we are on the throttle, we are not, and we're constantly letting off and putting it back on much more drastically than cruise. In addition, cruise control accelerates the vehicle slower, for example coming back up to speed after having to slow down significantly. (Well maybe not in all cars)

 

[blanchardsbronco]

i feel slight uphill and shitty gas

 

[BigMeatsBronco]

Alcohol doesn't have the BTU's of gasoline... So you need to burn 1/3 more of it than gasoline for the same power. Yeah, mileage is gonna suck ass.... But I've seen tuned turbo cars on e85 make ridiculous power

I thought that was common knowledge by now....but some folks need to read it over and over for it to sink in I suppose.

 

[BigMeatsBronco]

I could see this being the case if there was a lot of hills where the cruise control was getting on the throttle unnecessarily. But a relatively flat ground, cruise control will guaranteed save you gas mileage assuming you don't have it set at 85

The reality is that as steady as We may think we are on the throttle, we are not, and we're constantly letting off and putting it back on much more drastically than cruise. In addition, cruise control accelerates the vehicle slower, for example coming back up to speed after having to slow down significantly. (Well maybe not in all cars)

Actually the cruise accelerates FASTER than most humans in front of me...in fact in certain modes (normal and sport)I feel it's too fast. Also many cruise systems let the vehicle fluctuate up to 3-4mph. I know I can keep it within 2 mph with my foot without effort, (which equals consistency), so NO the cruise is NOT most efficient... ”hypermile” folks proved this wrong yrs back

 

[WuNgUn]

I thought that was common knowledge by now....but some folks need to read it over and over for it to sink in I suppose.

I've never even seen it for sale here in Canada, ever....
They just add alcohol to regular gas to save the planet

 

[DrBriGuy]

someone joked about a dropped valve in the responses. maybe it didn't drop yet but is struggling. would be worthwhile to have them all checked considering: https://www.bronco6g.com/forum/threads/2-7l-blown-engine-fail-list-28-so-far-jan-19-update.31951/

If you do have a faulty valve or other contributing component, many people would sure like to know about it.

 

[cricex]

You were heading north so you were going up hill....

Nope, got 14mpg average heading back to Austin.

 

[lenitech]

Actually the cruise accelerates FASTER than most humans in front of me...in fact in certain modes (normal and sport)I feel it's too fast. Also many cruise systems let the vehicle fluctuate up to 3-4mph. I know I can keep it within 2 mph with my foot without effort, (which equals consistency), so NO the cruise is NOT most efficient... ”hypermile” folks proved this wrong yrs back

My anecdotal experience in my Bronco is that the cruise maintains speed within 1mph and is generally dead nuts on at all times. Additionally, I have tested driving the same route multiple times with and without cruise and for me using cruise improved my mpg by about 0.5mpg.

 

[buzpro]

Using the displayed actual, trip, and lifetime.

The mpg display gauge is just estimating your usage, its not accurate at all. If you want proper measurements you have to do it the old style way.

Also:
1. ECO mode SUCKS ... you will use more gas believe it or not
2. Use 2WD normal mode on pavement (better for your tires too)
And
3. Skip cruise control

but when you go on a dirt road or something, sport mode is a blast!

 

[FlyingBronco]

I just drove from Denver to Utah and weather app said wind was around 15-20 in some areas. Relatively “calm” considering I have battled some serious winds in Wyoming. Always a headwind when traveling west. I averaged about 16.5-17 mpg. Not bad considering it was cold, at altitude, windy, high speed limits and driving an almost 3 ton brick. Curious to see the difference when I head back to Denver with a tailwind and gradual descent from 7500’ to 5280’.

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