Poor MPG
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Joined: Sep 2007
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From: Brighton, Co
well I'm in new hampshire now, I got about 14 mpg to begain with then the more i drove the better it got, towards the end I was getting around 16.5, dont know if its because its breaking in or if its the fuel, or the thicker air? I did notice my speedo is off, so I might have been getting better then this, My GPS was reading 78mph and my speedo was saying about 72mph, so you figgure 6 mph times 29 hrs thats an extra 174 miles divide by 4 or 5 tanks or so so I might have seen an extra 1mpg? I dont know
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Joined: Dec 2006
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From: Winchester, TN
My truck's best mileage for a long time was 17.89 MPG and that was a 450 mile trip on the interstate with the cruise on 70. I've had Edge EZ, Triple Dog, Quad XZT.....and they never got me better than that mileage figure. Usually always got around 16....with small stock tires or with my new big tires (speedo is re-calibrated). I just recently got my hands on a Smarty and started seeing better mileage. I'm now finally averaging in the 18-19 range...with my best being 19.87. In town, its a solid 15-16 if I drive right...
Just seems these 4x4 trucks are pretty solid at 15-17 MPG....not half bad considering how big the truck is.
And I agree with what Sevir said...if ya want GREAT MPG...get a 2WD diesel. I had a 2002 CTD 2WD and averaged 20-21 easily....best I ever got was almost 24 on a 650 mile trip...
Just seems these 4x4 trucks are pretty solid at 15-17 MPG....not half bad considering how big the truck is.
And I agree with what Sevir said...if ya want GREAT MPG...get a 2WD diesel. I had a 2002 CTD 2WD and averaged 20-21 easily....best I ever got was almost 24 on a 650 mile trip...
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Joined: Feb 2006
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From: vancouver
Your fuel milage will continue to improve for a very long time. The engine takes at least 60,000 miles to be completely broken in.
I have calculated my milage and it's killer if I don't push it, if I push it the engine get very thirsty.
I have calculated my milage and it's killer if I don't push it, if I push it the engine get very thirsty.
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Joined: Dec 2006
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From: Winchester, TN
Different truck I know, but my best ever was 24.6 MPG on a trip from UT to Washington State through the mountains of Montana and Idaho. I set my cruise at 66 MPH and never stopped for 741 miles. This is one tank of fuel mind you so no cheating possible. I filled up all the way to the top of the filler neck and the pump read 30.0xx gals. At that time, I was running 265 michelins with about 60 psi and no leveling kit. Now I have 315's and a leveling kit. I have a best of 20.6 MPG with cruise set at 65 over the same road. I obviously didn't make it the whole way at 20.6 and had to stop for fuel. I hand calculated both of these mileages and of course I add 11% to the 315 figure since my odo now turns 11% slower than it should. I checked this with 100 miles of roadside markers, gps, and police radar displays in construction zones. FYI 265's are 2.9% off as my stock tires were 245's.
Three comments:
#1 Big tires eat mileage!
#2 CTD's get better mileage when it is hot, not only is winter fuel lighter thus less btu's per gallon, the cummins is less efficient as temps drop. I believe somewhere in the neighborhood of 175* is the optimal intake temp for highest economy.
#3 Be sure to check your odometer for accuracy. 10 highway mile markers is 10 miles, if your odometer reads 9.7 for the same distance, you must add 3% to you mileage figure or multiply mpg by 1.03. An even better way to check is on a long trip with 100 miles of road. Every mile off is 1% thus every tenth off "easily viewed on dash" is 1/10 of 1%. " I get bored on long trips so my mind gets to doing math and other tedious things as I heard it down the road.
On a side not, when I got 20.6 on my last trip, my overhead read 29 MPG. I do have bigger injectors and fueling box etc that trick the ecm and make it read high. I do this same trip every winter and my cold weather trips never net more than 18.5 mpg.
Driving style changes numbers a ton as well. When I hotrod a lot, my mpg numbers drop down to the low 15's, high 14's.
Speed on the highway changes my numbers a lot as well. If I set cruise at 84 mph, I usually get around 15.5-16 mpg.
Three comments:
#1 Big tires eat mileage!
#2 CTD's get better mileage when it is hot, not only is winter fuel lighter thus less btu's per gallon, the cummins is less efficient as temps drop. I believe somewhere in the neighborhood of 175* is the optimal intake temp for highest economy.
#3 Be sure to check your odometer for accuracy. 10 highway mile markers is 10 miles, if your odometer reads 9.7 for the same distance, you must add 3% to you mileage figure or multiply mpg by 1.03. An even better way to check is on a long trip with 100 miles of road. Every mile off is 1% thus every tenth off "easily viewed on dash" is 1/10 of 1%. " I get bored on long trips so my mind gets to doing math and other tedious things as I heard it down the road.
On a side not, when I got 20.6 on my last trip, my overhead read 29 MPG. I do have bigger injectors and fueling box etc that trick the ecm and make it read high. I do this same trip every winter and my cold weather trips never net more than 18.5 mpg.
Driving style changes numbers a ton as well. When I hotrod a lot, my mpg numbers drop down to the low 15's, high 14's.
Speed on the highway changes my numbers a lot as well. If I set cruise at 84 mph, I usually get around 15.5-16 mpg.
Wrong. Colder fuel is more dense and contains MORE energy BTU's per gallon than warmer fuel. Don't belive me do a google serach on OOIDA hot fuel debate. There have been congressional hearings on the matter about how we get ripped off buying hot fuel with less energy content. Or maybe you can just ask some of our canadian friends on here who pump fuel from pumps that compensate for temperature differences. You see in Canada where the ambient temperature is much cooler than here in the US the oil companies lose a lot of money when they sell fuel that isn't temp compenstated. Whereas down here in the states, especially in the south, they rip consumers off selling us hot fuel that has less BTU's..
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Joined: Jan 2007
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From: Las Vegas, NV
JRaptor04, you said 78 on gps, and 72 on speedo. That is 8.33%. 8.33% increase on 14mpg = 15.16 mpg, 8.33% increase on 16.5 = 17.87 MPG. Those numbers sound about right to me. Why don't you try setting the cruise for 61 mph, which would really be about 66 mph. Fill up till you can see fuel in the filler neck, and then drive as long as you can stand it at 66 mph, then pull over, fill up to same point so you can get good measurement, divide gallons by miles, multiply answer by 1.083 and I'll bet you are at 20 mpg.
Diesel Junk, I didn't say anything about fuel temp, I was talking about "Intake Air Temp." If you understand a little about chemistry and thermodynamics, you will note that combustion is an exothermic reaction. Meaning it gives off enthalpy as a product, translated to layman terms, when you mix #2 with air it burns and releases energy in the form of heat. This means that the more heat you start with, the more heat you end up with = efficient horsepower. I like everyone else in the world know that hot fluids expand. Here's one for ya to think about, lets say you have the same weight of #2 in two different tanks. One tank is at 150*F, one tank is at 40*F, which tank will give more mileage?
Another one, you have two identical CTD's running down the road side by side. One has a 180* thermostat, one has 190* thermostat, which one will drive further on 10 gallons of #2?
One last one, one identical truck being fed air from the warm cab exactly 68*F. Fuel temp 90*F, Identical Thermostat, Same tires, Same everything, only difference is one truck is driving with outside temps of 40*, and one is driving with outside temps of 90*. Which truck will drive further on the same amount of fuel?
Diesel Junk, I didn't say anything about fuel temp, I was talking about "Intake Air Temp." If you understand a little about chemistry and thermodynamics, you will note that combustion is an exothermic reaction. Meaning it gives off enthalpy as a product, translated to layman terms, when you mix #2 with air it burns and releases energy in the form of heat. This means that the more heat you start with, the more heat you end up with = efficient horsepower. I like everyone else in the world know that hot fluids expand. Here's one for ya to think about, lets say you have the same weight of #2 in two different tanks. One tank is at 150*F, one tank is at 40*F, which tank will give more mileage?
Another one, you have two identical CTD's running down the road side by side. One has a 180* thermostat, one has 190* thermostat, which one will drive further on 10 gallons of #2?
One last one, one identical truck being fed air from the warm cab exactly 68*F. Fuel temp 90*F, Identical Thermostat, Same tires, Same everything, only difference is one truck is driving with outside temps of 40*, and one is driving with outside temps of 90*. Which truck will drive further on the same amount of fuel?
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AkitaSumo
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May 1, 2009 07:38 AM