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fxrdriller

Fuel Mileage

32 posts in this topic

I am wondering if everybody has seen there mileage go down with this new fuel. My mileage has been dropping and I figured it was mostly my transmission. Thanks to LUMPDOG! the afficiency of the tranny is back. So I checked my mileage after all of this and I am getting 14 MPG. That is terrible, I have to admit that there were a few burnouts! My overhead varies from 4 to 9 mpg off, from hand calculating it. It has no consistency what so ever and when I first got the truck it was fairly close. I ordered some new filters for my FASS so I can change them. I have not noticed my fuel pressure drop but, those filters have been on for a while. Any feed back would be appreciated! Thanks.:)

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I'm getting 16/17 mpg around town and 21/22 mpg on the highway as long as I stay under 70 mph. Above 70 mph, I get 19/20 mpg.

BTW, I drive an '07 Duramax tuned by IdahoRob and running a tow tune that dyno'd 421hp / 768tq ... :thumbup:

Rob

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A bad vp 44 will net bad fuel milage. On my 01 Dodge with it running right at 400hp setting i got 17-18 mpg with a 6 speed. I ran the edge juice with attitude.

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New fuel as in the ULSD that has been out for 2-3 years now?? :lol:

My truck gets about 15-16mpg. It seems that it used to get better, but I looked at the numbers since I keep track and it hasn't changed from the LSD to ULSD.

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Ummm....I remember seeing the stickers on a lot of pumps around here early last year that were still indicating that the fuel was not ULSD.

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I put a new vp 44 on last year. I picked up some new fuel filters for my fass today, but I was noticing that my fuel pressure is still around 17psi.

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It has been at the pumps for alittle over ayear I payed attention to where it was at becasue I was suppose to run it in my truck

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I haven't noticed any drop but when I do I change my filter and that seems to be the case...

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Ummm , what's your air filter look like? I have seen dyno runs were a dirty air filter will cost someone 25 HP. That tells me it would cost fuel mileage.

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I'm getting 17 in town out of my 02. and about 20ish on the hiway. And I don't baby it.

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My mileage is finally on the rise, got 19.5 this last tank, about 2 better than normal. Thou I am driving a tad easier and now have the Smarty Jr smokeless software.

I am towing the TT this weekend so I am curious what the new software will do for me.

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I have had this drop for awhile, I just have been blaming it on my tranny problems. Is there any way to tell if I have a bad injector? I havent changed my filter yet, I just started riding the Harley.

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Most likely a bad VP as mentioned elsewhere.

I am still getting 23 mpg even on summer fuel. ULSD has been at the pumps for a few years. The first year they didn't even notify the market.

Dave

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I Feel your pain i was getting about 16/17 in town and 19/20 hwy (if i could keep my foot out of it) and i have tryed diffent oil new filters and now i am luck to get 12/13 in town and 14/15 hwy. I would love any ideas to change that.

------------------------------------------------------------------------------

1999 Dodge 24V

F.A.S.S.

40 HP injectors

Bullydog Torque dog (60HP)

Intake

6" Exhaust

:train:

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ULSD has helped lower everyone's fuel economy. You can try cetane boosters and lubricity additives like 2 cycle oil. You might see some increase.

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Well, I just got back from Pinedale, WY and on I84 going to Idaho Falls I got 20.2 mpg at 78 mph. From IF to Pinedale WY and back I got 21.15 mpg. Most of those miles at 70 mph. All numbers were hand calculated.

FWIW, I'm running a 420hp/768tq, Rob Codden's tow-tune.

Thanks RC... :thumbup:

Rob

FYI, I do use Stanadyne Performance Formula at every fillup. Been using it since tank 1...

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I was running Rob's hot tune from boise, made an in town stop at Mountain home, and then here to Twin and averaged 21.4 going 85 on the freeway.

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I was running Rob's hot tune from boise, made an in town stop at Mountain home, and then here to Twin and averaged 21.4 going 85 on the freeway.

That's the tune I dyno'd 473hp/920tq. FWIW, I drove to Minden Nev. last Thanksgiving running that tune and got 22.6 mpg...

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Darn good mileage numbers Rob. That 6 speed Allison with it's double over drive is a god send for anything over 70 MPH. My truck's MPG drop like mad at anything over 70MPH which is 2000RPMs. Seems like the magic number is under 2000 for the 6.0

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Darn good mileage numbers Rob. That 6 speed Allison with it's double over drive is a god send for anything over 70 MPH. My truck's MPG drop like mad at anything over 70MPH which is 2000RPMs. Seems like the magic number is under 2000 for the 6.0

Yeah. I didn't check the mileage coming back from IF though. There was a 30+ mph head wind yesterday...

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I just checked my mileage today and it was 17.5 mpg. This is in town and a lot of stop and go. Basically it took 4 weeks to get 435 mi. So my mileage is coming up. I almost think that I had a clogged injector. I have not gone on any long trips in awhile. So I have nothing to compare with highway but, when I travel on the freeway I go 80 to 90.

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Mine dropped in the last month or so,from 20-22 empty to 17 empty,driving like I was trying to get 22....not sure what the hell.

Used to get about 12 hauling,now getting 8.5

who knows?

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I am at 15-16 empty, town or hiway, pretty close, might be a 14 in there... loaded worst ever with a bad IP, was 9.8, but I weighed 14,760. Not the heaviest loaded pickup I ma sure, but that is some weight. And that was from SLC to St. George, then up through Tonopah, over to Cali, though Benton, and Benton Hotsprings, South Lake Tahoe, then on into Sacramento that is a shitty grade, had to granny over the top to keep the temp down, course I drive scared of the temp gauge, 2/3-3/4 I am dropping gears to where the engine isn't laden, or as lightly laden as it can be.... 25-30 up the grapevine in 2nd (1st real gear, 1st is granny obviously).

With the IP from my 6.9, I see 11- 13 loaded... I am resealing injectors tomorrow, and attempting an exhaust leak as well. It is on the main feed pass bank to turbo, that is 1-2 right there, and I know the pooling diesel under my truck when I idle somwhere isn't doing anything awesome for my mpg, and I have a genuine certified bought it at Lake City fuel filter that needs to go on.

The only "Bomb" this truck has, is a K and N with a homemade intake.

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