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Discussion Starter · #1 ·
I recently came upon a good deal on a 03 GMC CC dually with only 16k miles on it. I am only getting 10 mpg:eek: now. I was wondering when I could expect to start improving on the mpg?
 

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I have 30K on my 03 ccsb and get 18 avg combined city and hwy. that seems exceptionally low
 

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The day I bought mine, I got 9! on the first tank empty. I changed the fuel filter and got 14 on the second tank pulling a 6000 trailer.. This was with 50K miles.
 

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Where are you located? Winter blends cause MPG to go down. Also, when was the fuel filter changed last, or any maintenance?
 

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10 miles per gallon, thats crappy, like 260 miles per tank, i will do double that... you need to install a 60 to 100 tune, help the mileage out lots
 

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Discussion Starter · #6 · (Edited)
I am in WY so the winter blend might have something to do with it. I looked back on the service records that I was given & found that the fuel filter was just replaced only a couple of thousand miles ago. Any other recommendations?
 

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Is this hand calculated? Are the tires the stock size?
 

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Discussion Starter · #8 ·
10 miles per gallon, thats crappy, like 260 miles per tank, i will do double that... you need to install a 60 to 100 tune, help the mileage out lots
FREDW --I am NOT real knowledgable on the "upgrades/aftermarket" stuff. Can you or someone inform me of what a "60 to 100 tune" is? Will this void any of the warranties?
 

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that doesn't seem quite right, then you haven't mentioned your driving style, distances, towing or anything else. I can get anywhere from 14 to 22 mpg depending on overall conditions and drive. Normally this time of year i'm in the 16 to 17 range, summer months, my truck sits a lot, but add 2 mpg to totals.
 

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FREDW --I am NOT real knowledgable on the "upgrades/aftermarket" stuff. Can you or someone inform me of what a "60 to 100 tune" is? Will this void any of the warranties?
what FredW meant was a hand held programmer or a module (box) would help you out some.

It would not void the warrenty as long as you unplug the box or un-load the tune from the truck.

A few good ones are edge(box),bully dog(hand held),predator(hand held),and there's others,but those are the most popular,then there is the crazzy stuff.

also if you go w/ an edge gett he attitude,which shows boost and egt's. If you go w/ a handheld get a set of gauges. 0-30psi boost and 0-1600EGT
 

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Diesels also preform best when warmed up. My milege varies alot depending on how much city vs freeway driving I do. If your making alot of short trips it will drive down the milege, especially this time of year when its cold out. My brother lives in Moorcroft near Gillette....
 

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yes find an cheap aftermarket box, this can give a few miles per gallon right there, winter fuel will hurt the mileage a bit, and i found running the winter fronts when real cold will give better mileage as well

your setup should yeid you close to 15mpg, yours seams a bit low for sure

pm me for more details
 

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Before you get a "60 or 100 tune" you need to find out why your truck is only getting 10mpg. First double check your calculations. Then you might want to see if you have a bad injector. I would take it to your local dealer just to have it checked out.
 

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The only time I have gotten below 14MPG is when towing either my v-nose snowmobile trailer or 26ft travel trailer and then I get 11-12.5. I'm always in the 16-18 range unless running in 4WD over snowy roads in very cold weather, then I'm at 14-15. I didn't think duals hurt the MPG that much but I could be wrong...
 

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Do you idle your truck much? I know if I idle my truck about 10 min in the morning before driving it I got about 10mpg. I have since cut my idle time to about 5 min and now my mileage is around 15mpg. Just something else to think about.

Hop
 

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Mine's getting 17-18 mpg on winter fuel. Almost every trip is at least 15 miles from home. Has about 27K miles and is totally stock except for accessories in sig.
 

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I'm running a mild VA 70 hp tune. Has made absolutely no difference in mileage whatsoever. I'm running about 17 mpg (US), at close to gvw rating.
 

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My fuel mileage usually was 16.25 unless I towed or something else made it lower. Now after 18000 miles I switched to synthetic and my first tank was 17.25 and the next was 18.25 and the third after installing hypertech was 17.38. This is all city driving which includes short trips down the highway. I can't explain why.
Kirk
 
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