fuel mileage down the tubes

bigp38 · **Joined:** Thu Nov 09, 2006 5:44 pm **Posts:** 23

i have recently replace my exhaust with a flowmaster outlaw race muffler made my cat a high flow and upgraded to 245 75 16 maxxis mudders now i am at about 17 mpg its there anyway to bring it up some maybe a chip

midwest · **Joined:** Tue Apr 25, 2006 12:03 am **Posts:** 173

The lift and tires will cost you every time.

wenied · **Joined:** Wed Dec 21, 2005 4:01 pm **Posts:** 107

What's wrong with 17?

We've been getting 17-18.5 for all in town (45mph or less) driving for 1.5 years now and that's with stock tires.

Still gets 25-28 on trips

BVCRD · **Posted:** Wed Feb 07, 2007 9:38 pm

wenied wrote:

What's wrong with 17?

We've been getting 17-18.5 for all in town (45mph or less) driving for 1.5 years now and that's with stock tires.

Still gets 25-28 on trips

I'd say you are short a mile or two than the rest of us in town.

spencevans · **Posted:** Wed Feb 07, 2007 10:03 pm

I was getting 23-24 around town and 27-28 on the highway before F37. Now I am only getting 15 in town and 18 on the highway. I also have a lift and tires but I was getting great milage before F37, now it just stinks.

bigp38 · **Joined:** Thu Nov 09, 2006 5:44 pm **Posts:** 23

i was getting 21-23

RFCRD · **Posted:** Wed Feb 07, 2007 10:43 pm

bigp38 wrote:

i have recently replace my exhaust with a flowmaster outlaw race muffler made my cat a high flow and upgraded to 245 75 16 maxxis mudders now i am at about 17 mpg its there anyway to bring it up some maybe a chip

Did you have your odometer recalibrated for the larger tire size? Those tires are large enough to understate your odometer mileage @ 5%. Also, if you are driving in the cold, you mileage will fall off sharply. I have been lucky to pull 20 mpg from last few tanks running all expressway due to the cold.

litton · **Posted:** Wed Feb 07, 2007 10:57 pm

Don't forget that "around town" is very subjective. Driving around in LA would be totaly differant then those of us in...say Tucson where I can get 22. When we go to San Diego, my "around town" drops to 19.

spencevans · **Posted:** Thu Feb 08, 2007 2:13 am

RFCRD wrote:

bigp38 wrote:

i have recently replace my exhaust with a flowmaster outlaw race muffler made my cat a high flow and upgraded to 245 75 16 maxxis mudders now i am at about 17 mpg its there anyway to bring it up some maybe a chip

Did you have your odometer recalibrated for the larger tire size? Those tires are large enough to understate your odometer mileage @ 5%. Also, if you are driving in the cold, you mileage will fall off sharply. I have been lucky to pull 20 mpg from last few tanks running all expressway due to the cold.

The computer will compensate upto two tire sizes but a recalibration may still be neccesary.

65thKJ · **Posted:** Thu Feb 08, 2007 8:51 am

How can the computer compensate for tire size changes?? It seems like you would need a reflash to compensate for the new tire size.

Emos Way · **Posted:** Thu Feb 08, 2007 9:33 am

bigp38 wrote:

i have recently replace my exhaust with a flowmaster outlaw race muffler made my cat a high flow and upgraded to 245 75 16 maxxis mudders now i am at about 17 mpg its there anyway to bring it up some maybe a chip

Look at the hardware I'm running.. I'm about 17-18 or so.. I do have the EDGE module and love every minute of it.. more power with no reduction in fuel economy.. possibly went up.. but I'd have to get off the pedal to notice..

ATXKJ · **Posted:** Thu Feb 08, 2007 11:19 am

The computer can compensate - if you reprogram the tire size - which the dealer can do - I'm not sure if an EVIC can or not - personally - my speedo was off with the stock tires and is much more accurate with the 245/75/16 MTR's - however I did lose about 1-2 mpg - the MTR's are about 24 lbs/wheel heavier than stock tires - it takes a lot more energy to start them moving and to slow them down, so stop and go traffic impacts it more than highway.

DarbyWalters · **Posted:** Thu Feb 08, 2007 12:36 pm

The dealer can reprogram your computer for a larger tire size but I would rather get the longer warranty...lol

If you can use someones GPS to figure out the mph difference and adjust your miles traveled by that percentage you will get a better gage on mpg. If you tires make your speedo and odometer read 5% slower you have added 5% to your warranty time :idea:

clday25 · **Posted:** Thu Feb 08, 2007 3:14 pm

I'm with DW, take advantage of the slower Speedo/Odometer readings.

With using speed-traps, mileage test, miles traveled, Google maps, ect. I've figured an average speed difference of 6.4% and I'll take it!

Mpg wise, after the % difference from the new tires and 4,700 miles driven I'm getting an average of 19.5..... sure is better then my old TJ!

RFCRD · **Posted:** Thu Feb 08, 2007 8:52 pm

65thKJ wrote:

How can the computer compensate for tire size changes?? It seems like you would need a reflash to compensate for the new tire size.

Must have missed buying the automatic resync option, probably part of the GPS/Nav package??? :lol:

fuel mileage down the tubes

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