Suffer poor MPG???

[Old Jeeper]

I had this happen when I ran on 35s, Mopar lift, on the stock 3.45 gears. I was getting 13 MPG on the highway as well. The transmission wouldn't shift beyond 5th and 6th gears.

As soon as I re-geared, the transmission started shifting to 7th and 8th gears again. I now get 15 MPG at 75 MPH; 18 MPG if I stay under 70 MPH.

I would think with my 4:88 cogs that getting to 7 & 8 would be fast and easy, LOL.

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[av8or]

I didn’t read through this whole thread, but I’m going to point at gears. My JLUR when stock was great, then I put on 35 inch Goodyear mtr tires and I had similar results. My trans rarely shifted into 7th or 8th, and mileage on the highway was 13-15mpg hand calculated. Then I went to 37s and never really checked the mileage but it was obvious the gearing wasn’t going to work for the 3.6.
After changing gears to 5.13s the number one and two biggest differences was now it hits 8th gear on the highway always and I get 17-18mpg.

 

[Bryce]

I would think with my 4:88 cogs that getting to 7 & 8 would be fast and easy, LOL.

Sure sounds like something is wrong here. I have no issue getting into 7th and 8th in my JLUR with 35s (315/70R17) and stock 4:10 gears in my '19 JLUR. If you have 4.88s and 35s, there should be no issue with getting into the upper gears.

6th is a 1:1 ratio in the transmission, and 7th and 8th are both over drives at .84 and .67. So if you are never getting into those, your fuel mileage is surely going to suffer, like you are seeing.

 

[azjl#3]

I would agree, if the tire/wheel acceleration and rotation is assessed in isolation. When you look at the combined vehicle weight, aero, frictional losses, tire rolling resistance, and all driving conditions, the acceleration of the tire/wheel is small. But the lever arm of the tire still works to exacerbate all of those variables, while the tire/wheel weight acceleration requirements remain constant.

agreed to a point. Changing only the Tire weight/size will dramatically effect MPG.

When I put Toyo 35s on, they weigh about 105lbs, up from 65 lbs KM2s, my mileage took a dive from 17 to 15. a 12% mileage hit only for tires. Sure, put a rack on with a tent, more loss. I also noted braking was more an issue, trying to stop rotating 100lb tires.

 

[Old Jeeper]

agreed to a point. Changing only the Tire weight/size will dramatically effect MPG.

When I put Toyo 35s on, they weigh about 105lbs, up from 65 lbs KM2s, my mileage took a dive from 17 to 15. a 12% mileage hit only for tires. Sure, put a rack on with a tent, more loss. I also noted braking was more an issue, trying to stop rotating 100lb tires.

Take a look at ECB Green pads, I use them WHAT a DIFFERENCE it makes and I put on a drilled disk, all only up front, rear is fine.

Also look at the ECB Orange pads.

 

[3TV]

No off road and less than 3k miles since last Oct. I just noticed it due to sound in the cab about a week ago and did not think about to much. But I had to drive down south to Naples FL and about 200 mi rd trip and that is where I really discovered it...at 75 mph, loud engine and high rpm and it was in 6th. I was not driving it hard or pushing it, just on Cruise control. I will be trading it soon when my 2024 JLR-X gets built and let the dealer sort out.

Headwind? Both ways no less.

 

[Old Jeeper]

Headwind? Both ways no less.

No, not that day, besides I 75 is a N-S road and the winds comes from the W Gulf of Mexico mostly since I 75 is on the west side of FL....

 

[Jeepeto]

I quit watching my MPGs long ago and I’m a happier person for it

 

[Old Jeeper]

I quit watching my MPGs long ago and I’m a happier person for it

Cost of fuel is just the cost of getting there, no more, no less...

 

[multicam]

I’m just happy to get Miles Per Gallon rather than Gallons Per Mile

MPG > GPM

 

[roaniecowpony]

I’m just happy to get Miles Per Gallon rather than Gallons Per Mile

MPG > GPM

I try not to look. My 2018 has 29,000 miles on it. I don't drive enough miles a year to make much difference in the scheme of things.

 

[CBIRD]

Interesting. I have 37x13.5 Nitto Ridge Grapplers with Black Rhino 22lb rims for a total weight of 118 lbs per wheel/tire. I also have steel, bumpers, a heavy duty spare tire carrier, door hinge steps, and a 12K lb winch, so my JLU is pretty heavy. I get into 7 & 8th gear easily and get 21+ MPG at 65 on the highway, about 17 mpg at 75-80 mpg, and 15-16 around town. And I have a lead foot. I did adjust the tire size with my Taser, but I still have 4.11 gears. 2L turbo using premium gas

 

[Mos.Jeep]

Stock Rubicon 2L just finished 1,200 mile highway trip got just over 22mpg doing 90% trip at 75+ mph

 

[Ratbert]

They said they did it when I put them on which was back around Dec. Just noticed the engine nose this past week., not even 3k mi since Oct. I don't it often. So will live it since most drives are at city speeds and let the dealer sort out when I trade in for my 2024 JKR-X that should be on the way in early Aug.

If they neglected to do that then that could explain your transmission shifting issues. The simplest way to verify that they did it is to compare what a GPS-based app says your speed is versus the speedo. If they didn't adjust it your speedo will say that you're going slower than you really are.

 

[racerdude90]

I switched to 35’s not long ago but have not checked what gear i’m in. now i’m curious, if i remember i’ll switch the display and see what gear i hit on the freeway

also if i had a dollar for every time i read someone dismissing good mpgs on here i would buy a 392. idk what the deal is with that lol

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