12.5 mpg all the time?

Piscatory_7 · **Joined:** Tue Sep 22, 2015 12:53 am **Posts:** 11

I'm getting very poor fuel mileage from my 2002 Liberty Sport 4x4. I drive highway sometimes and logging roads sometimes, doesn't seem to matter, every time I fill the tank it's 12.5 mpg. It rolls easy so doesn't seem like brake drag, the engine is new (I just installed it, a rebuild), transmission seems to be fine and oil is still red. Tires are 245/70/16 Cooper STT so I think that could be affecting some but not that much. Dirty/wornout injectors? Engine runs and idles smooth, fires up easy. Does have OME lift. Got new plugs, started with NGK Iridium but changed to Autolite copper. Stock intake with new filter. Is this typical for a liberty with larger tires? 190k on the vehicle but only 1k on the engine.

Gageraid · **Posted:** Fri Oct 02, 2015 12:25 pm

The tires are what's holding you back and the engine should get more mpg after it breaks in at I believe 15K miles.

PhilW55 · **Joined:** Tue Sep 29, 2015 5:41 pm **Posts:** 8

The tires have that much effect? I'm considering a regear to 4.10 to help.

tommudd · **Posted:** Fri Oct 02, 2015 10:16 pm

Don't need to regear for a 29 inch tall tire, ( 245-70-16s ) get up to 30-31/32s yes
You've got other issues, when was the last tuneup?
Good set of copper plugs every 30,000 miles does wonders

riptricket · **Posted:** Fri Oct 02, 2015 11:21 pm

Lol didn't buy a jeep for the mpg...
I get 13 no matter how I drive.
J.E.E.P.

PhilW55 · **Joined:** Tue Sep 29, 2015 5:41 pm **Posts:** 8

tommudd wrote:

Don't need to regear for a 29 inch tall tire, ( 245-70-16s ) get up to 30-31/32s yes
You've got other issues, when was the last tuneup?
Good set of copper plugs every 30,000 miles does wonders

245/75/16 are about 30.5 calculated. Have not physically measured them. New engine, filters, plugs. I was thinking 16 All around. Son in law claimed about that.

PhilW55 · **Joined:** Tue Sep 29, 2015 5:41 pm **Posts:** 8

riptricket wrote:

Lol didn't buy a jeep for the mpg...
I get 13 no matter how I drive.
J.E.E.P.

Well didn't buy expecting samurai fuel economy but hoping for better than 12.5. That's like a70's 350 chev. :roll:

Arkie · **Posted:** Sat Oct 03, 2015 12:54 pm

PhilW55 wrote:

tommudd wrote:

Don't need to regear for a 29 inch tall tire, ( 245-70-16s ) get up to 30-31/32s yes
You've got other issues, when was the last tuneup?
Good set of copper plugs every 30,000 miles does wonders

245/75/16 are about 30.5 calculated. Have not physically measured them. New engine, filters, plugs. I was thinking 16 All around. Son in law claimed about that.

Some folks'll lie to ya! ;-)

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mass-hole · **Posted:** Sun Oct 04, 2015 2:47 pm

Piscatory_7 wrote:

I'm getting very poor fuel mileage from my 2002 Liberty Sport 4x4. I drive highway sometimes and logging roads sometimes, doesn't seem to matter, every time I fill the tank it's 12.5 mpg. It rolls easy so doesn't seem like brake drag, the engine is new (I just installed it, a rebuild), transmission seems to be fine and oil is still red. Tires are 245/70/16 Cooper STT so I think that could be affecting some but not that much. Dirty/wornout injectors? Engine runs and idles smooth, fires up easy. Does have OME lift. Got new plugs, started with NGK Iridium but changed to Autolite copper. Stock intake with new filter. Is this typical for a liberty with larger tires? 190k on the vehicle but only 1k on the engine.

Not the same, but I drove my F150 cross country starting from 1200 miles on the Odometer. All 2300 miles was on I-70 and other 65mph roads and I averaged like 13.2 mpg all highway. Now that I am at 16.5k miles I am averaging 17 mpg daily driving, so highway, 50 mph back roads and in town. Long highway trips will get me around 19mpg if i'm careful.

The point is, I would think you will get a some better mileage once things wear in a little bit.

WolverineFW · **Posted:** Sun Oct 04, 2015 3:17 pm

Did you check to see if your brakes are dragging? Calipers might be stuck.

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u2slow · **Joined:** Sun Mar 11, 2012 7:26 pm **Posts:** 160

My gf pulled off 18mpg this summer on some highway trips. Thats with the V6, 6spd, 3.54 gears, 245/75R16 tires, 2" lift.

Most of the time mpg is less, but overall, roughly the same to fuel the Jeep as one of my old cummins trucks. :lol:

John3:17 · **Posted:** Sun Oct 04, 2015 4:00 pm

One question, do those tires happen to be on 16x8" aftermarket steel wheels?

PALiftedKK · **Posted:** Sun Oct 04, 2015 4:21 pm

riptricket wrote:

Lol didn't buy a jeep for the mpg...
I get 13 no matter how I drive.
J.E.E.P.

same.

was the air filter replaced? maybe upgrade to a K&N drop in unless you have a CAI. using the recommended oil?

was the engine a 3.7l or different? I think that needs to be addressed first. :2cents:

PhilW55 · **Joined:** Tue Sep 29, 2015 5:41 pm **Posts:** 8

John3:17 wrote:

One question, do those tires happen to be on 16x8" aftermarket steel wheels?

No, they are factory alloys from a wrangler Rubicon of about the same vintage, 2002 or so.

PhilW55 · **Joined:** Tue Sep 29, 2015 5:41 pm **Posts:** 8

Update: I did get 14.9 on one fill up a short time after changing out the break-in oil. Put in 5-30 standard non synthetic and will change that out at about 3500 miles. Another tank was 13.8 mpg but it included running around some logging roads. New engine must have a greater effect than I thought it would.

12.5 mpg all the time?

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