Mileage SUCKS!!!

[Doughboy21kd]

My mileage is not that great on this new truck... . I know alot of it has to do with only having 1k on it... . But why would my mileage go down after putting miles on it... . When i started out with 10 miles on it and for the first fill up... All mileage is being hand calculated...



2nd fill: 14. 5 mpg



3rd fill: 14. 2 mpg



4th fill: 11. 8 mpg



5th fill: 10. 8 mpg



Yesterdays fill was: 9. 9



Now all these fills the tank WAS NOT empty... I top off once a week so it doesnt hurt the wallet as bad.....



Any ideas??? THANKS



(This is on dads 6. 7... . Not the truck in the sig below)

 

[Wolfy]

My mileage is not that great on this new truck... . I know alot of it has to do with only having 1k on it... . But why would my mileage go down after putting miles on it... . When i started out with 10 miles on it and for the first fill up... All mileage is being hand calculated...



2nd fill: 14. 5 mpg



3rd fill: 14. 2 mpg



4th fill: 11. 8 mpg



5th fill: 10. 8 mpg



Yesterdays fill was: 9. 9



Now all these fills the tank WAS NOT empty... I top off once a week so it doesnt hurt the wallet as bad.....



Any ideas??? THANKS



(This is on dads 6. 7... . Not the truck in the sig below)

Ideas only, no answer:



You say nothing about driving style or loading. Are you becoming more careless or hot-roddish, with increasing familiarity with the rig? Carrying heavier loads, through more traffic, or through hillier country?



The fact that the trend is not irregular, (up-down-up), but increasingly, and steadily "down", indicates, if all your use conditions and fill-level are consistent, that something is wrong, and getting "wronger".



I. e. , if the "trend" continues, you will soon be getting 5mpg. In that case "something wrong" will be undeniable, and most-likely noticeable enough for the service people to find and fix.



Regarding your frequent fill-ups: if you fill a 100 gal tank , but happen to stop short by 1/2 gal, you have effected your "reading" by 1/2%, if at the next fill you top off the tank completely.



If, instead, you put only 10 gals. in, and are short by 1/2 gal,... you have affected your reading by 5% (instead of 1/2%).



Bottom line: If you are after the best accuracy, larger-volume fills will give less % error for any mistakes you make regarding the relative completeness of the fills.



your wallet won't know the difference if the gas money is managed well.



$150(or whatever)/mo. will be the same whether paid in 1 stop or 4. (Your time/trouble investment will be less with 1 stop.



Now that I think about it,... your trouble is obvious :

too-frequent fill-ups.



Since the mileage goes down with every fill, ... the solution is also obvious:

fewer fills!

 

[betterthanstock]

My theory is that these trucks will be OK mileage wise for heavy towing, but empty, they suck the fuel.



Probably the particle filter is getting a little clogged (compared to a brand new one), not that that in itself would cause mileage to go down that much, but that it needs more regenning, which wastes more fuel.



While towing, the engine produces more heat, so that either keeps the particle filter cleaner, or needs less fuel to get it hot to regen.

And it's a 6. 7 vs a 5. 9, so it will burn more fuel at light loads.



The EPA wanted to emulate the gasser emissions (inefficient combustion, little NOx, but lots of CO (the tradeoff), even though OSHA lists CO as much more deadly than NOx), so it looks like mileage is starting to emulate the gassers too.



I posted on here having seen a Chassis Cab with a real smokey exhaust. I wonder if they figured that by poking a small hole (or welding a small bypass) to the filter/pipe, it would regen a lot less (better mileage), but still not set a code?

Kind of expensive to find out, though a bypass valve might allow some adjustability... ... ... . Still, that thing was puffing a small cloud every time he was accelerating a bit, so it may be that these engines are real heavy smokers compared to classic diesels, without the particle filter to catch the smoke. That would explain the lousy fuel economy.



Why would they be real smokey? To cut back on NOx emissions, which are the product of very hot (and efficient) combustion. Does this make you wish Cummins had gone for the cow urine (no joke) bottle injected into the exhaust (like Mercedes), and left the combustion process more efficient, without EGR and all that? I wonder if it could have met the 07 standards (probably not the 2010, like it does now).

 

[TKeeler]

My mileage is not that great on this new truck... . I know alot of it has to do with only having 1k on it... . But why would my mileage go down after putting miles on it... . When i started out with 10 miles on it and for the first fill up... All mileage is being hand calculated...



2nd fill: 14. 5 mpg



3rd fill: 14. 2 mpg



4th fill: 11. 8 mpg



5th fill: 10. 8 mpg



Yesterdays fill was: 9. 9



Now all these fills the tank WAS NOT empty... I top off once a week so it doesnt hurt the wallet as bad.....



Any ideas??? THANKS



(This is on dads 6. 7... . Not the truck in the sig below)

I am just over 1600 miles and my last two fill ups have been 13. 62 and 13. 66 but I did see 17 immediately upon returning from the 600 mile trip driving the new truck home...completely different driving conditions, lots of cruise control and highway. I fully expect to see better than 13. 62 with highway/freeway driving. The 13. 62/13. 66 includes some stop and go driving.



As a comparison my 98. 5 (also auto with 4. 10) would take about 28 gallons at each fill up which was usually around 400 miles. The '07 is again at the 400 mile mark but taking a gallon or two more to fill. For the type driving I do back and forth to and from work the slightly lower mpg with the 6. 7 doesn't seem unreasonable. Afterall I went from a hp/torque of 210/415 to 350/650.

 

[y-knot]

You really don't have enough miles on the truck to establish a reliable pattern. Yes your mileage went down, but your only on the 5th tank or so, start worrying after 3-5K miles. The truth is the new trucks are not going to get the mileage the older ones did, it just a fact. All the EPA equipment and larger displacement prevents that.

 

[jeepit]

You really don't have enough miles on the truck to establish a reliable pattern. Yes your mileage went down, but your only on the 5th tank or so, start worrying after 3-5K miles. The truth is the new trucks are not going to get the mileage the older ones did, it just a fact. All the EPA equipment and larger displacement prevents that.

Report back after you have 60,000 miles on her... ...

 

[betterthanstock]

I assume you looked for the obvious, like a fuel leak. Check your oil level.

 

[Doughboy21kd]

Yeah oil level is fine..... Under the truck is bone dry..... I dont know? But in an early post someone had said that its too frequent of fill ups... . Seems silly but the way explained somewhat makes sense maybe?????



Although i dont know his driving style all that well that might be the problem as well as only having 1k on it..... On my 06 i didnt notice a jump in mileage til about 10k on the clock... . But noticed my biggest increase when i made my truck SMARTY... :-laf :-laf Oo.



guess well just hope for the best and keep rackin up some miles on it... . Unless anyone else has some idea... THANKS

 

[LesStallings]

I wonder if the fuel tank vent is causing problems with getting a consistent fillup. Slight uphill, downhill, left-right can make the venting very different with the stock vented tank.



It does seem to be a consistent decline in mileage. Thank goodness diesel is cheap...

 

[Wolfy]

... in an early post someone had said that its too frequent of fill ups... . Seems silly but the way explained somewhat makes sense maybe?????

Everything in my post after "Now that I think about it," was only a joke.



Everything above it was real.



The main point was that all the driving conditions and fill-ups have to be consistent, week to week, if you want to make accurate mileage comparisons.



Good luck!

 

[Jeb_H]

My 6. 7 got better fuel mileage when I first got it and then got steadly worse till finally setting at 9-10 pulling and 12MPG empty and highway. Still runs OK but not like I would think a motor with 350HP and 650 torque would run though.



I do think we need to hope that BullyDog hurries with the new PMT they have coming out in maybe July for these LOL... I think they have a power pup out now or if not soon to be out. I just will hold out for the PMT as I want the guages as well, to help moniture everything.



I was told to expect mileage to go up around 10-15K on the truck, mine towing a 27' gooseneck 95% of the time and all the time 5 days a week, I feel certain its broken in enough and still no better mileage...



The Dodge place has ordered a new EGR valve and a few other things along this line to help CLE that I have been getting on and off for quite some time. Maybe the mileage will get better then. I don't expect it too though. I do hope that once the Bully Dog PMT can be had, that it will allow me to remove all the EPA nazi crud off this motor and save it from an early dealth

 

[GShelton]

My mileage is not that great on this new truck... . I know alot of it has to do with only having 1k on it... . But why would my mileage go down after putting miles on it... . When i started out with 10 miles on it and for the first fill up... All mileage is being hand calculated...



2nd fill: 14. 5 mpg



3rd fill: 14. 2 mpg



4th fill: 11. 8 mpg



5th fill: 10. 8 mpg



Yesterdays fill was: 9. 9



Now all these fills the tank WAS NOT empty... I top off once a week so it doesnt hurt the wallet as bad.....



Any ideas??? THANKS



(This is on dads 6. 7... . Not the truck in the sig below)

My mileage started out at 14. 3 for the first refill, went up to 16. 1 for the second tank. The third tank was 17. 6 - mostly Highway with cruise set at 65. 300 miles after the last fill arrived home with the overhead reading 20. 0 mpg. I am hopiing when I fill again to be at around 18 mpg judging from the gauge reading.

George

 

[Jeepstang]

we hit a new record high for my truck this weekend of 15. 1 mpg and that was with my wife driving.

 

[MEvins]

My mileage has been terrible. 13. 2 Highway and city, 8. 7 Towing Highway. I currently have 13,000 miles.

 

[Wolfy]

we hit a new record high for my truck this weekend of 15. 1 mpg and that was with my wife driving.

Terrain? Speed? Load? Style(conservative/aggressive)? Mileage on odometer?

Rear axle ratio?



Interested because new truck will be similar, except Quad-cab.



Thanks,

 

[Jeepstang]

Mostly flat Terrain with some rolling hills with a recliner chair in the bed and six adults in the truck. I have about 1500 miles now. She drives very easy on the skinny pedal.