Cause for significant drop in mileage in 2.7 L?

[cricex]

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.

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[j_marinelli]

I've had my 2.7L for about two months and have made 3 road trips with it, just crossed 3000 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.

Were you loaded down with more weight on this trip? Or maybe going against a heavy wind?

 

[cricex]

Were you loaded down with more weight on this trip? Or maybe going against a heavy wind?

Nope, less weight this time.

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

 

[Roll Sound]

I've had my 2.7L for about two months and have made 3 road trips with it, just crossed 3000 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 run my tires at 37psi on road, and I've tried Normal and Sport modes a bunch, and done the same road trips a few times. Oddly, I get about a mile per gallon better fuel economy while cruising on the highway in Sport mode. I can get 20mpg going from LA to Tahoe. Go figure. I thought it was a mistake, or maybe I got a tailwind or something, but it's been consistent.

 

[cricex]

I run my tires at 37psi on road, and I've tried Normal and Sport modes a bunch, and done the same road trips a few times. Oddly, I get about a mile per gallon better fuel economy while cruising on the highway in Sport mode. I can get 20mpg going from LA to Tahoe. Go figure. I thought it was a mistake, or maybe I got a tailwind or something, but it's been consistent.

Interesting. My tires are all at 40psi for the highway.

 

[WuNgUn]

It's definitely colder now than it was 2 months ago....
And winter formulated gas is shittier for mileage.

 

[Roll Sound]

Interesting. My tires are all at 40psi for the highway.

So your mileage wasn't low psi related either. Interesting. Maybe try Sport mode for fun? Keep it on for a tank? I'm curious your results. Is my truck crazy? Haha!

 

[Murfman]

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.

You are also going uphill big time, coming from Texas.

 

[cricex]

It's definitely colder now than it was 2 months ago....
And winter formulated gas is shittier for mileage.

Colder would mean more dense air and better mileage, but to your point, it could be winter gas. Didn't think about that.

 

[cricex]

You are also going uphill big time, coming from Texas.

It was ~13 MPG the entire time, even in West TX which is flat.

 

[Jdc]

Don't know if you've already done it but @Cat put together a nice checklist to go through.
https://docs.google.com/document/d/1bCKnGypjpN2g2Qz8UtEC1-eqGUeqm5g9fj0tdrady3E/edit
I believe several folks have complained about loose turbo hoses( Turbo Charge Air Cooler Hose ). Might be worth checking out.

 

[desert_rat]

was your average speed the same? I've read posts where mpg is significantly different between 55mph and 75mph

 

[cricex]

was your average speed the same? I've read posts where mpg is significantly different between 55mph and 75mph

75-80mph, just like my other road trips where I got ~18mpg.

 

[Roll Sound]

You are also going uphill big time, coming from Texas.

I go over a few big summits to get to Tahoe. I averaged 20mpg. Both directions. All 420 miles. Driving around town is where I get hammered with mileage. I'm averaging 14.

 

[WuNgUn]

Colder would mean more dense air and better mileage, but to your point, it could be winter gas. Didn't think about that.

You're looking at it the wrong way. Cold, dense air definitely helps make more power... But you're not wanting more power cruising down the highway at the same speeds you were going in the autumn. However, colder denser air creates higher resistance to passing thru it, so in all likelihood, you were needing more power...

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