Really really bad MPG...

[a_guerrajr]

I went from 18 to mid 13's with heavy trail grapplers and leveling kit.

I went down to stock height and 22's and am at 16

 

[king99]

The mileage booster tune in my R/T got worse gas mileage than the 93tune did. My truck almost felt like it was straining with the booster tune. It was very odd, guess it was because of my 4.10's?

I completely agree, mileage booster felt like truck was working extra hard to get moving. So far, other than bone stock tune the Hemifever 93 tune is the best mileage at 12.6+/- a little.

I put the stock tune back in and pulled the neg battery cable to reset computer and I was back to about 13-14+/-. Then I downloaded Hemifever 93 but then realized I had 87 in the tank so went back to stock until I can get a tank of 93. I think I am going to pull the neg cable again to reset then download a fresh Hemifever 93 tune and see what happens. I feel like writing the computer over and over again something gets lost in translation and screwed things up.

Maybe I should just download the Hemifever tune and stop whining about it and enjoy all the power.

Maybe a set of rear gears will move those big ole tires better.

 

[craigsez]

Stock wheels and tires weigh in at 75 according to another post I looked at. I honestly do not see the 35x12.50x20 trail graps and your rims weighing in at 83 sadly. lol
Id say the rims are around 30 and the tires around 80 alone. Just guessing.

I feel your pain though. You're gonna have people saying "what do you expect". lol But I agree with you.

Get this.... I'm pretty sure my fender flares added a decent knock to my mileage! Gonna play around with it when I get home and see what happens. I'd like if someone made an underbody aero dynamic package for our truck for when we lift. something from the front bumper to guide the wind over the cross members and etc. instead of it just hitting the cross members getting chopped. < am I grasping at straws? lol

Dont know about the flares costin mpg but im almost sure an under belly areo kit would help...I drive a rig for a liven and i listen to a sirius radio program about areo stuff for big rigs....Same probs with wind hitting the trailers axles,so a company came up with a system that redirects the air under the axles...I dont remember the company off hand but there is a claimed mpg increase so i dont see why it wouldnt help in the auto world..Heck the cars that run daytona and all the tracks have a solid bottom for that purpose..

 

[Casper]

If GPS is reading 50mph Speedo is at 53mph. Don't ask my how or why but thats what they are reading. Works out wel when I am not paying attention because if i am speeding at least its 3mph less than I think I will have to try 33.5".

I do have it leveled. Pulled out the 3" kit and put in Bilsteins all around. Not that that makes a difference but just figured i'd throw it out there.

In regards to the weight of the wheels and tires i'm sure I was off on that. For some reason I remember seeing someone post that their 35's came in at about 83lbs but again I'm sure I am off on that.

The strange thing is that no matter what tune I have downloaded the MPG is basically the same. You would think that there would be some sort of difference given that different tunes mean difference fuel consumption. I figured i'd at least see a difference running the mileage booster tune.

If you have only witnessed this dramatic decline since about November (or as it got colder), you may want to consider that winter formulated gas (ethanol and other oxidizers) has fewer BTUs per volume measure and therefore delivers worse miles per gallon of fuel consumed. If your mileage suddenly improves in the spring, you'll know its chemistry and not aerodynamics (or not entirely aerodynamics).

 

[Chewy]

Dont know about the flares costin mpg but im almost sure an under belly areo kit would help...I drive a rig for a liven and i listen to a sirius radio program about areo stuff for big rigs....Same probs with wind hitting the trailers axles,so a company came up with a system that redirects the air under the axles...I dont remember the company off hand but there is a claimed mpg increase so i dont see why it wouldnt help in the auto world..Heck the cars that run daytona and all the tracks have a solid bottom for that purpose..

I see those on I-80 all the time. HUGE plastic wedges mounted just forward of the rear trailer axles to shove air under them. That and the side pieces to keep the air streaming down the side.

 

[king99]

Dont know about the flares costin mpg but im almost sure an under belly areo kit would help...I drive a rig for a liven and i listen to a sirius radio program about areo stuff for big rigs....Same probs with wind hitting the trailers axles,so a company came up with a system that redirects the air under the axles...I dont remember the company off hand but there is a claimed mpg increase so i dont see why it wouldnt help in the auto world..Heck the cars that run daytona and all the tracks have a solid bottom for that purpose..

Maybe someone here has the skills to fab something up. In my mind it seems pretty easy. Almost like a skid plate that bolts up to redirect wind.

 

[Chewy]

Maybe someone here has the skills to fab something up. In my mind it seems pretty easy. Almost like a skid plate that bolts up to redirect wind.

Yes, but in a truck you have a driveshaft and exhaust to contend with as well as ground clearance.

It's doable, but I don't think in this application you'd see a large enough gain. Putting a larger wind dam on the front to compensate for the lift would probably help more than anything. That of course would look stupid. Look at the GM Hybrid trucks and there huge lower front wind dam. UGLY!

 

[dtru1222]

Is your truck 4x4?

Weight from 4x4, your sub and amp, 3 inch lift and 35 inch tires and your only getting 3 mpg less than I am. I would say theres not much you can do about it because it sounds about right to me.

Plus the 180 stat doesnt let your engine burn gas as efficiently.

 

[SFD213]

I have the 93 tune installed and it been the best for me, not only in power but mpgs as well. Now bigger tires isnt gonna kill you drastically, as long as you have a balanced driving route (hwy/city)
I have a 2500 qclb, and although it doesnt have a lift, level, or 35s, when i went from stock 31.5s to 33s, my mpgs went up nearly 2 mpgs with the speedo dead on.
The trick is how you drive. Driving like grandma from up the block isnt gonna save you because its making next to no power for the fuel you put in, but driving like a lunatic isnt going to help. I keep it, within reason, not much higher than 2500 rpm and then cruise around 60, but not use cruise control. Now i dont drive like a pig nor run around like speed racer.

Cliffs notes: 91 tune is best for both and be mindful of how you drive, it really does help beyond belief

 

[Slowpar R/T]

The only thing that comes to my mind is how you are calculating Mileage; Are you hand Calculating or going by the in-dash display?

 

[Andrew09HEMI]

Also, switching back and forth between tunes wont give you accurate results.. From what Ive recorded when using the DiabloIntune on the last 3 hemi's it took about 3 tanks to get the mpg accurate. At first it shot up drastically, then down and then finally leveled out at 12.5 city and 19.1+ highway at 72 mph or less. Im not sure if its just my experience or anyone elses but thats what I see. Now recently my mpg has dropped under 11.5, Im do for oil change, my cats are shot and Im been even more inpatient with Charlotte drivers.. I assume youre up to date on maintenance?