How do I achieve better MPG? - Diesel Truck Forum -
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post #1 of 10 (permalink) Old 11-19-2007, 03:34 PM Thread Starter
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How do I achieve better MPG?

Hello All, I am new to the site, have lurked before and see that everyone likes to help out..And I need help. I have a 2001 Chev. Duramax 3500 dually with a MPRP 4inch exhaust and an AFE stage 2 air filter. What would be my next step in order to get some better mileage? I have been told to get a programmer but is there something else?
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post #2 of 10 (permalink) Old 11-20-2007, 12:38 PM
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Probably not what you want to hear, but driving discipline turns out to be the most significant factor, things like predicting your stops and planning. Rolling for 400 yards without throttle is free mpg.

Otherwise, tire choice, tire inflation, avoiding the temptation to lift it, a tonneau cover, are a few things that help.

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post #3 of 10 (permalink) Old 11-20-2007, 12:46 PM
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I don't think a tonneau cover would be cost effective. Saw this one on mythbusters.

Tailgate Up or Down Revisited: Mesh tailgate, hardcover, tailgate removal
See: Tailgate Up or Down

For the original myth they did a driving test and a water vortex test, both of which showed that you save more gas with the tailgate up. Their viewers suggested that they test three new conditions:

Hardroof cover over pickup bed
Mesh tailgate
Remove the entire tailgate
They had a much simpler test setup this time. They had an electronic flowmeter hooked into fuel line of Jamie's pickup. Adam: "For anyone out there that wants to e-mail telling me that we screwed up this test, we have already calibrated this thing, to this car. So it's going to be perfect!" They drove the pickup truck up and down the stretch of 101 around Candlestick and the Cow Palace.

Tailgate down: 5.2 gallons/hr @ 55mph. 1.2 gallons/hr @ 25.
Tailgate up: 5.0 gallons/hr @ 55mph. No reading for 25mph given, but tailgate up was once again confirmed as more efficient.
Hardcover over pickup bed: 5.0 gallons/hr @ 55mph. 1.2 gallons/hr @25mph
Tailgate mesh: 5% more efficient
Tailgate removed: about the same as tailgate up and hardcover
Mesh was most efficient by 5%

still busted
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post #4 of 10 (permalink) Old 11-20-2007, 02:25 PM Thread Starter
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Thanks for the insight, I have noticed the difference of driving it easier, but I like to hear the echo through the subdivision.
As for tire choice what if I was to get bigger tires that would still fit under the truck without lifting it, from experience, would it make a noticible difference with the MPG?
Also I already have the tailgate removed, not for mileage, but so that the wife doesn't back over cars in the parking lot.
Thanks for the help.
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post #5 of 10 (permalink) Old 11-20-2007, 02:51 PM
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Personally I went from the stock tires to a 285 a/t tread and saw no change in mileage. Now when I run my 285 m/t's I lose about 2 to 2.5 mpg on the highway.
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post #6 of 10 (permalink) Old 11-20-2007, 07:32 PM
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Some sort of tuner or a canned EFI Economy tune would be next. I dont know if your into the performance but I wish I had got the DPS2(?) EFI live and had a street tune and an economy tune.

But I have a predator by Diablo and run teh 85hp tune and still get 18-19 no the highway.


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post #7 of 10 (permalink) Old 11-21-2007, 12:46 AM
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2000rpm is the magic number with the DMax. Keep it at/under that RPM, and you get good mileage....over that the mileage drops off fast.
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post #8 of 10 (permalink) Old 11-21-2007, 03:43 AM
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I have a 03 lifted with 35's and they save you fuel once your at cruising speed but it takes more to get them turning so it would depend on your driving. If it's mostly around town then stay with the smaller tires and if mostly highway then MAYBE bigger tires. You can also get a tranny kit to turn a 5 speed Allison into a 6 with Suncoast Transmission. That would definitely help your MPG but the up front cost will be a bit.

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post #9 of 10 (permalink) Old 11-21-2007, 02:27 PM
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Like Tom said 2000rpm is definately a big factor. Running 285" M/T's cut mine down a bit but running 255" M/T's actually increaded it a bit. A good EFI tow tune/economy can help. My buddy sees 20+ with a 80-100HP tune but my Dad gets 20-21mpg on his stock D-Max quite often. Too bad I haven't mastered the ability to drive with a light foot.

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post #10 of 10 (permalink) Old 11-24-2007, 04:22 PM
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I think curtis (before he broke his truck) said he got 21 or 22mpg with an economy tune and 305s, but yeah a programmer is your best bet, keep your tires at 55psi also. I've heard with the PSD's (not sure about the DMax) that the exetreme race tunes get the best mileage....Its definitly worth a shot..

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