Hi all,
picked up an 08 dakota crew cab laramie with the 4.7 last week (90k on it). Love the truck so far but it seems to be going through fuel faster than expected. Im getting 10-12mpg doing mostly rural 2 lane highway 45-55mph ish driving, sorta hilly here but nothing crazy and i dont drive particularly aggressive so i was expecting more like 15 at least. No engine light on and not obviously running rough or anything. Any suggestions or is that just how these trucks are?

 

Cold weather + winter gas = lower mpg's. I need to check my tires, probably low since it's cooled off.

 

Welp ... First thing I would do is a tune up and replace the air filter, oil and oil filter, check tire pressure .... If no improvement after that dig deeper. Injectors and spark plugs. Try some additives like Zmax or Gumout. Some peeps use a tuner for economy. First thing I did when I bought my Dakota R/T was buy an air filter at Crappy Tire on the way back from the dealership.

 

Is the tcc locking up? What are you revving at 55mph?
https://www.fueleconomy.gov/feg/Find...25067&id=24956

 

TCC seems to lockup normally, running about 1800ish at a steady 55. found a tire was like 10 psi low, perhaps that will improve things some. saw another thread where poster was having similar problems, replacing the O2 sensor fixed it, wondering if thats a possibility considering im not showing an engine light? Planning on giving it a tuneup/oil change/air filter/etc this weekend when i head home, just got the and have been out of town for work since that and haven't really got under the hood yet

 

Also don't forget in cold weather, the air density along with longer warm up times... higher electrical loads, defroster use, higher rolling resistance on cold tires. I usually drop into the 13's every winter.

 

You are at the appropriate mileage for a tune-up including replacing both sets of spark plugs. That might help some.

 

[QUOTE=rjohnny89;3418377]TCC seems to lockup normally, running about 1800ish at a steady 55. found a tire was like 10 psi low, perhaps that will improve things some. saw another thread where poster was having similar problems, replacing the O2 sensor fixed it, wondering if thats a possibility considering im not showing an engine light? Planning on giving it a tuneup/oil change/air filter/etc this weekend when i head home, just got the and have been out of town for work since that and haven't really got under the hood yet[/QUOTE
lazy 02 is possible. their is a 02 monitor that test the switching times but it could be passing but near the failure point. pre cat 02 only...post 02 are not used for fuel metering.
checking the plugs is not a bad idea...it its running rich you may see a black plug.
check the fuel trim readings with a scan tool...they should be within +/- 10%. at idle and 2500 rpm...the truck uses speed density fuel metering...anything that skews map readings will skew fuel trim ie. rich mixture

 

Yeah these things aren't the most efficient. Basically 90% the size and capability of a Ram 1500 with 100% of the crappy mileage.

I do think you should see a little better than that but there are too many variables that affect it. To compare, I have a 2011, 2WD crew with 4.7. I've had between 12.6 and 13.5 mpg over the last 10 or so fillups. I've seen as low as 7.2 on e85 while towing and as high as 22.9 on a trip to New Orleans while actively trying to drive sensibly.

I actually bought new O2 sensors also but haven't put them in yet. Looks like the uppers are going to be a real pain and am just putting it off.

My average has a lot of factors such as the 4.56 gear, 20" Ram wheels, wider 285 tires which add to aero drag and I tow a 6x12 utility trailer about 90% of the time. I am honestly impressed I get that much as I'm not gentle with the gas pedal. I use the remote start quite often which I'm sure takes a measurable hit to the economy also.

I'va seen the same complaints even on the new Ridgeline and Colorado owners. There are some owners that are only getting 12-15 mpg and it just boils down to their specific use and environment.

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4.56 gearing? what did you swap in to get that? Was a direct fit?