03 liberty 13mpg.help

[jrp79]

just bought a 03 liberty sport 3.7 2wd.new plugs,new air filter.has 217k miles.only code is bank 2 sensor 2 high voltage but shouldnt effect anything.average mpgim getting is 13-14mpg.normal driving.oem tire size is 215-75-16 and have 235-70-16 on it now which is the same size in height but alittle wider.
it runs great,no skips,no hesitation.what could be causing me to only get 14mpg?

 

[CzarKJ]

If the O2 sensors are reading incorrectly it could be telling your computer to give it more gas messing with the air/fuel ratio. Just an idea.

 

[tjkj2002]

just bought a 03 liberty sport 3.7 2wd.new plugs,new air filter.has 217k miles.only code is bank 2 sensor 2 high voltage but shouldnt effect anything.average mpgim getting is 13-14mpg.normal driving.oem tire size is 215-75-16 and have 235-70-16 on it now which is the same size in height but alittle wider.
it runs great,no skips,no hesitation.what could be causing me to only get 14mpg?

In bold is your issue,also the type of plugs used can effect mpg's also.

 

[jrp79]

In bold is your issue,also the type of plugs used can effect mpg's also.

i used ngk cooper plugs.i thought downstream o2 sensors were only there to make sure the converters were doing there job and have no effect on drivability

 

[LibertyTC]

Replace with NTK sensor bank2 and replace the rear axle lube would be a good idea.
My Jeep is heavy & lifted with 245-17's and all is up to speed, and I only get 15mpg on the hwy.
Get alignment/bump up a few lbs in tire pressure, empty interior load, drive easily /not spirited, all have effect on fuel mileage.
Even Dave would agree the jeep can be a "pig" on fuel! ha ha..
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I did not buy it for the fuel mileage! :gr_grin:

 

[tommudd]

Drive it like you stole it
driving any of mine easy they get crappy mileage
fast take offs/ 75 -80 on the highways/ the right gearing / 21-22 all day long

 

[LibertyTC]

Gearing does help for sure.
Spirited driving today for KJ after adding some..
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Had it to the floor to blow the carbon out. I burned a 1/4 tank pretty quick!
Jeep seems to have liked it though!

 

[HoosierJeeper]

Drive it like you stole it
driving any of mine easy they get crappy mileage
fast take offs/ 75 -80 on the highways/ the right gearing / 21-22 all day long

x2. I started "not babying it" (I don't abuse it, but letting it hit 3-4k RPM for accelerating if possible with traffic, I don't try to keep it low), and now in town I get 15MPG instead of 13. I've also stopped letting idle to warm up, just start it and go.

I tested the highway speed and I get better MPG at 75-80+ (about 21-22MPG) than like 70-75 (17 MPG), but with a speed limit of 70, a ticket would negate the gas savings...:favorites68:

 

[Jeremy-WI]

A bank 2, sensor 2 issue should not affect mileage as it should just measure catalyst efficiency. I would use a scan tool to check what the Intake Air Temp and Coolant Temp sensors are reading as the computer will compensate for cold temps with extra fuel