Another mileage question?

[Lifted Mega]

First off let me say that i did a search and brought up numerous posts regarding this issue. But not specific to my question. What im wondering is my mega is 1 month old and ive put 4300 miles on it already. From day 1 this truck have been reading on the overhead 12. 5 mpg at 70 mph if i run up to 74-76mph my reading is 11mpg. Upon checking by hand calc. it was less actually 10. 3mpg. When empty not towing and driving at 53mph (rpm1400) i will see the overhead read as high as 16mpg, But no one drives that speed. That is the best ive ever seen. Was your guys mileage actually that low then increased as you put more miles on it? I love the truck but this mileage sucks!! What im wondering is possibly having the ecm flashed to see if that helps. I really don't want to start adding programers and ect. I don't want to mess with the warranty, thats the reason i bought a new truck and sold my 96 dodge diesel. What do you all think??? Oh by the way i live in cental calif and this truck has been driven up and down the valley no hills at all. The truck has been to Oregon and ive also pulled a car trailer once with a toyota tercel on it with about the same mileage as empty. Thanks Jeff

 

[roperteacher]

Sounds pretty Low. I bought mine Dec1 06 and it's an o6. I got 18 around town right off the lot and iv'e seen 22 on the open fwy going 65 ( 2000 RMP). 12 pulling a huge trailer.

 

[Mark1si]

I have an 05 with 30k on it and I get 10-12 mpg in town and 15-17 on the highway @2k rpm unloaded

 

[jelag]

I've got 3 trucks... 04, 04. 5 and 05, all working... the 04 pulls 22K most of the time... and gets 10 - 11 mpg stock... now with 230K miles... empty all the trucks see around 15-18 when driven under 2,000 rpm on the highway... . when we push the speed limit that drops 1 - 3 mpg... . the 04 has never had a tank full of fuel when the truck didn't have a load on it... . so its real mileage empty might be different...



We saw improvement's when the trucks had 4500 to 5000 miles and it sort of leveled off... . Don't know if this is the answer your looking for... .

 

[SMasters]

Lifted Mega - Did you recalibrate your speedo for the 35" tires? I have a 07 Mega dually. It has about 2500 miles on it. I am getting 16 mpg at 65 mph all highway burning winter fuel. I hope it goes up a little once we start burning #2 this summer.

 

[Lifted Mega]

Thanks guys for the help. I still seem way lower than everyone else i guess. I still have yet to pull my 38ft toy box. If what i'm currently getting is any indication to what to expect it will go down to 7mpg towing my trailer. I sure hope something changes soon!!!!! Any ideas as far as flashing the ECM? I called the service mgr to ask if there are any updates need to flash the ECM he told me that were no flashes needed for my truck that he was aware of. And just flashing the ECM won't help the mileage. But i told him after they lifted the truck and put on the 35" tires shouldn't the ECM be flashed he said he never heard of that. I wondering if even knows what he talking about?

 

[SKing]

go to your dealer and have them plug into your truck and change the revolution size of your tire to the correct tire size. I have 38s with 456 gears on my mega and I get 13-15mpg. It cost about $65 to program or you can buy a programmer/scan tool at most car part stores for about $150 and change it yourself.

 

[p-Bar]

go to your dealer and have them plug into your truck and change the revolution size of your tire to the correct tire size. I have 38s with 456 gears on my mega and I get 13-15mpg. It cost about $65 to program or you can buy a programmer/scan tool at most car part stores for about $150 and change it yourself.

You need the DRB III scan tool dealer only

 

[raxley]

I thought Smarty would change tire sizes? LOL, a $685 tire diameter changer (not counting performance!)

 

[Lifted Mega]

Talked to the GM at the dealership regarding if the ECM had been flahed after they had the truck lifted and 35" tires installed. He said that he was unaware of that needing to be done and doesn't beleive it was done. Basically i need to prove to them its required after the mods they did. This is the first truck they have every had lifted w/ bigger tires sold new. So now my mission is to find another dealer or the shop that lifted it to convince them that its needed. Or maybe i will just tell them(dealer) that the overhead display has been giving me somw funky readings along with a rough idle (1-3sec)when first starting in the morning so they will flash the ECM.

 

[Lifted Mega]

 

[SKing]

WOW You mean to tell me that they sold you a vehicle with a false reading speedo as well as a false reading odometer. Hope its not auto. I would hate to think that you have drove around with improper shift points. Sounds like all your readings. like odometer and shift points are all wrong in your ECM. . Your tire size dictates how all these functions work. If your dealership is so stupid to sell you a truck lifted, and not recalibrate your ECM to the new tire size I would tell them to buy back the truck due to stupidity. Any lawyer would eat there lunch in a case like this as I know due to the fact my wife is a lawyer. If you asked them to put the lift on and they made you sign a as is statement they are still responsible if they didn't do it right. All the dealer has to do is plug into the port under the dash and go through the list on the hand held computer stop at tire size press enter and then program the revolutions per mile of your tire. It sound like there to stupid to know that so you might have to call a tire store and tell them what tires you have and ask for the revolutions per mile witch for most 35s is in the 600 range. Print this post take it to your dealer so he knows that we know how stupid they are.

 

[SKing]

And its not a flash its a reprogram.