08 Libby 13 mpg

[Travis85904]

I just bought an 08 Liberty limited 4x4 and am getting horrible gas mileage. It has 70k miles, stock 18" wheels, 3.73 gears, automatic trans. The best mileage on a fillup so far has been 13.5. I bought this coming from a Ford Expedition and was hoping that I would gain a few MPG due to the unibody construction on this rig. I've even read in other forums users reporting 17-21 mpg. I probably do 60% city driving with the rest being highway. I've already replaced the spark plugs and was sure to use the oem plugs and also replaced the air filter.

 

[4x4kayak2112]

City driving will kill it....

Sent from my SM-N900P using Tapatalk

 

[uss2defiant]

maybe some fresh gear oil?

 

[4x4kayak2112]

You got the copper core plugs? Also what are they gapped at?

Sent from my SM-N900P using Tapatalk

 

[HoosierJeeper]

That does seem a little low for city driving, I get 14-16 in town even with the bigger tires, lift, etc. Recently I aired up the tires from 33 to 36 and went from barely getting 15 on the highway to getting 19-21. I'd try that too.

 

[uss2defiant]

someone here changed their fuel injectors and got a crazy high mpg.
Don't remember who it was.

 

[RenKJ]

I just bought an 08 Liberty limited 4x4 and am getting horrible gas mileage. It has 70k miles, stock 18" wheels, 3.73 gears, automatic trans. The best mileage on a fillup so far has been 13.5. I bought this coming from a Ford Expedition and was hoping that I would gain a few MPG due to the unibody construction on this rig. I've even read in other forums users reporting 17-21 mpg. I probably do 60% city driving with the rest being highway. I've already replaced the spark plugs and was sure to use the oem plugs and also replaced the air filter.

Look into the usual stuff for the 3.7, pcv valve in particular, try running a batch of full synthetic and see if it starts to dirty unusually fast, might indicate some gunking, also city driving is Brutal for the KKs as i believe they're heavier than the previous model

 

[Travis85904]

I just changed to oil and I normally run Mobil1 full synthetic anyways. Seems to be helping a little bit. Last tank got 16mpg but that was mostly highway. I will try replacing the pcv valve and look into the fuel injectors. Interesting thing about the tire pressure. Mine are around 32-33, I will try airing them up to 36 and see if that helps.

 

[twowings]

What's your commute like? That right foot can be your worst enemy if you get impatient or aggressive...

 

[troutbum]

City driving ,I stay in the eco zone. My 2012 get's 16 mpg. I live 9 miles from my part time job, so i have a 18 mile round trip each day i work. My trip consist of a few country roads, but mostly city. I have had the Liberty for 2.5 month,s now and have yet to take a long trip with her. I would like to see what she will do on a trip.

 

[teeje]

Depends on how you drive. I got 23mpg last night city. 2002 Jeep Liberty. Yet I have a new engine with only 3000 miles on it so I wouldn't know


Sent from my iPhone using Tapatalk

 

[Travis85904]

Honestly i feather the gas pedal. Especially with the mileage ive been getting. I filled my tires from 31 to 38 psi and i got 16 mpg on a long freeway drive... but since then its been back around 13.5, mostly city driving. This is really frustrating =[ I even ran some seafoam through my gas tank and I really don't believe in that kind of stuff.

 

[RenKJ]

Honestly i feather the gas pedal. Especially with the mileage ive been getting. I filled my tires from 31 to 38 psi and i got 16 mpg on a long freeway drive... but since then its been back around 13.5, mostly city driving. This is really frustrating =[ I even ran some seafoam through my gas tank and I really don't believe in that kind of stuff.

Seafoam in the gas might not do much, something with a pea additives like gumout regane will clean things up, if you dont live in Mountain areas you could try switching the differentials to synthetic gear lube.

In the end the kk is almost 1k lb heavier than the KJ but has the same engine.

 

[dude1116]

New plugs? New coil packs?

 

[Travis85904]

Already replaced the plugs. And have no reason to suspect the coil packs are bad

 

[Travis85904]

Just had something come to mind. I have the 18" optional wheels, I wonder if that's what's hurting my gas mileage so bad.

 

[tommudd]

Just had something come to mind. I have the 18" optional wheels, I wonder if that's what's hurting my gas mileage so bad.

Wheels do not hurt mileage as far as diameter, tire size will if you go up 2-3 sizes

 

[HoosierJeeper]

They probably weigh a bit more over the 16s or 17s. But probably not a big difference, could probably look it up.

 

[LibertyTC]

Anytime you see bad gas mileage a tune up check is in order. PCV definitely.
How did your plugs look when you pulled the old ones? Got any pics?
Have you cleaned the throttle body?
Ever run 2 bottles of some decent fuel injector cleaner in full tank like Chevron Techron Concentrate?
I just also seafomed mine with new coil packs.. ah much better!
Mostly city driving, is major carbon build up waiting to happen!
Solid highway runs blows the dirt out, and premium octane may helps clean the engine, w/ long duration trips, which is when to add the Injector cleaners.
(of course keeping safety & speed in mind) Take a trip, ler er rip, none of this put put stuff, over drive off, get the rpm's up to the floor occasionally, & I bet your fuel mileage goes up as carbon burns off!

 

[profdlp]

I'll second the motion on gear oil, but I'd do the PCV for sure. I've also become a fan of Marvel Mystery Oil. (I've never trusted or liked any of that stuff before.) Buy the big bottle and it will carry you through about four tankfuls if used as directed, at which point you should see some improvement. I also (re)gained a few MPGs by getting an alignment.