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No matter what i do. My 04 awd 5.3L tahoe VIN Z is eating gas badly. It has 26" wheels and ive done about everything to it that i can think of to improve and nothing is working to compensate for the extra weight the wheels have. Ive put a cat back flowmaster exhaust, spectre cai.,new fuel filter, new msd wires and ac delco plugs, the 2815 flashpaq, and nothing is helping. Getting around 10.5 mpg city probably around 14 ish hwy. Currently running tow tune with all superchips values, Ive tried every tune and none do any better. Anyone got any suggestions besides taking off wheels? Truck runs great no dtc's, just bad gas mileage. And I have adjusted the tire size option on tuner correctly. Anybody?

Mine's an 04 AWD too, and I noticed that the only thing that really seems to have any significant affect on my MPG is my lead foot.

In the last three weeks I have added a Magnaflow catback, and the Cortex Perf Tune to my K&N 77 intake already on my hoe. I get a little bit better mileage, but not much. (maybe 1.5-2mpg better). I'm in the same boat you are, minus the 26" rims. (I'm running the stock 17"s with Michelin AT2s)

I assume that with the mods you've done you check the tire pressure, and don't buy crappy gas. (if yours is a FLEX Fuel, you're better off running cat @ in the tank than ethanol, if you want HP, MPG gains...etc.) I make sure to keep the throttle body clean, and the MAF clean. I'm considering an e-fan upgrade to free up the HP lost on the clutch fan. Don't know how much it will help, but it's a cheap mod and worth a try. A

I have read that the AWD hoes just *h gas. Period.

If you find something that works please let me know!

BH

bahollis

Thanks for the input about your hoe.



Measuring the tire height physically on the truck with a tape measure, for a correct set up. What kind of mileage are you getting on the stock tune with the tires corrected.

Ron

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Ron, running the Perf tune with 3.73 gears and my tire info corrected I get anywhere from 12.7 - 13.7 MPG highway. The problem is, my daily commute is a tollway (70mph speed limit) and I'm only on it for about 8 miles. I run about 80mph to keep from getting run over, and that's no bueno for my MPGs in this 5,600 lb monster. After that, it's stop & go traffic for another 5 miles which also makes my MPG *h.

I'm going to Abilene this weekend (200+) miles, all highway (65MPH speed limit)
and I should get a better idea of what my real highway mileage is, and I will report it back to you when I return.

BH

Just drove the hoe to Abilene, loaded with people & heavy crap.

Using the Perf tune with tires corrected. I got 14.5 mpg avg.

I expected higher, but I feel like I'm riding a race horse on a walking path. I got on it at about 65mph to pass a slow poke, and was topping 90 in seconds. It's scary quick for a 5600 lb AWD SUV.

I'm going to try a different tune on the way home and see what happens.

BH

OK, I tried the same trip back from Abilene to Dallas, using the straight unmodified Mileage XS Tune. With the cruise set at 70 or below almost the whole way (198 miles), I had 17.4 MPG. That's nearly 3 MPG gain over the 91 octane Performance Tune I used going out. I used 87 Octane on the Mileage XS tune too. And to top it off, I had an extra person & their luggage on the trip back. The acceleration was not as quick, but I had the cruise control set most of the trip, so who cares?

Sooooo, if I want to drive it like I stole it it's the 91 Octane Performance Tune. If I want to drive it 400 miles without gassing up, the Mileage XS tune. I was very happy to see a significant difference in MPG between the two tunes too. I have seen where some have had pretty much the same numbers.

I can't wait to try the 87 octane Performance Tune.

Ron, what's so special about the Mileage XS tune? I mean, whats so different from the 91 Perf tune that I got 3MPG gain?

BH

i currently have the XS tune in mine for the first time. i am almost on 'E' right now and have had it in the whole tank. i have done extensive testing with the 91, tow, and stock, in my '07 Ram 1500 4x4, Quad Cab, 4.7L.
what i have found so far with over 1000 miles of driving on each tune was 10.8 stock, 12.4 tow, and 12.7 perf 91.
the truck is 100% stock with 15,000 miles on it. these numbers are pretty low because about 75% of my driving is less that about 3 miles, meaning it never gets up to operating temp.

so far on this tank my overhead is reading about 13.7 but i drove about 50 highway miles on this tank.

yes i have corrected the tire size in the performance tune, they measure 32.5 inches exactly. Tire pressures are correct all the way around. 40 psi is the recommened pressure for these size tires, 305 30 26, .Running stock tune is even worse, i think, although i cant say ive actually tried it. All i know that running stock with the 26"s is like driving a 4 cyl. Dont know what else to try, have tried them all perfromance stock 87 and tow, is there something else i can do with the tuner to try out, And where is this cheap elec. fan set up that bahollis is talking about? cheapest ones ive found are anywhere from 600 to a grand.?

here you go. it's a DIY write up, but it saved him several hundred dollars.

Web://z71tahoe-suburban.com/iboard/ind ... 19926&st=0

Honestly, I would be saving up for a gear change on the truck, to do it right. Pricey, but it is what you need.

Ron

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not wanting to hijack your thread but trying to keep all info in one place.

UPDATE: i just filled up after running a whole tank with the mileage XS tune. 270.6 miles and 22.602 gallons=12.0 mpg. about 50 miles of this was highway. not very impressive but i will try a few more tanks. i reviewed my past results and had some perf. tune tanks that were this low also but it averages 12.7 so i'll update as i obtain more data.

and i drive it like a grandma! this was in 90+* weather so the AC was cranked up the whole tank.

Okay, i'm jacking this thread a little bit since it was already started on gas mileage. I have an 06 4.8 V8 crew cab. I use the FLaspaq 2865 in Economy mode w/ my wheels changed as needed. I am getting worse mileage now than I have in performance mode> I don't get what else to do. No I don't put my foot in the gas. I drive a constant 70 mph or less too and from work everyday. Over 60miles each day..