Low Gas Mileage

[ZiadKiwan]

Hello Jeepers!
my jeep Liberty 2003 Sport V6 3.7L does MAX 80KM/20L in Mixed road 120KM/20L in HIGHWAY, it's a second hand jeep that i bought it ~ 2 years ago and since i bought it i was not confident with its gas mileage but my dad told me its normal, but i kept trying to fix its mileage it didn't work until at last i gave up, what i did:

1- Changed Spark PLUGS and COILS.
2- Changed Engine Oil type.
3- Change Gearbox Oil.
4- Used Fuel Injector Cleaners.
5- New Oil Filter For Gear Box and Engine.
6- Changed the Engine Temperature Sensor.
7- No Check Engine Light Problems.

i couldn't find a solution :shrug: , so please help!!
PS: my friend have a Grand Cherokee Laredo V6 4.0L 2000 and his gas mileage is 100~120KM/20L and he lives just next to my house... so please help.

 

[dude1116]

For all of us imperial users I believe that's ~9MPG city, 14MPG highway.

To the OP - have you modified this KJ at all? How long have you had it? How many miles are on it? Could be worth it to change the rear (and front - but not as important here) dif fluid...but I don't think that would get you all of your mileage back. O2 sensors might also be a good investment to change as well...although you would likely be getting a CEL if you had an issue there.

Engine oil should stick to 5w-30.

Bear in mind that winter will SERIOUSLY drop MPGs due to cold, warming up your Jeep, and Winter gas.

Edit: realized you're in Lebanon now. Might not be an issue.

 

[CzarKJ]

Ok so converting... it gets around 9mpg mixed 14mpg highway. That is slightly lower but not out of the range of possibilities. What type of plugs did you put in? Could you specify but what you mean changed engine oil type? How does the air filter look?

Also I see you are in Lebanon. What do the highways look like there? What is the typical speed you are traveling and elevation?


Edit.. Dude beat me!

 

[tombo_ontario]

I'd check tire pressure (I know it's sounds obvious), brakes may be rubbing somewhere, make sure you used plain old copper core spark plugs, clean air filter, proper alignment...soooo many things that could be the issue

 

[ZiadKiwan]

~

For all of us imperial users I believe that's ~9MPG city, 14MPG highway.

To the OP - have you modified this KJ at all? How long have you had it? How many miles are on it? Could be worth it to change the rear (and front - but not as important here) dif fluid...but I don't think that would get you all of your mileage back. O2 sensors might also be a good investment to change as well...although you would likely be getting a CEL if you had an issue there.

Engine oil should stick to 5w-30.

Bear in mind that winter will SERIOUSLY drop MPGs due to cold, warming up your Jeep, and Winter gas.

Edit: realized you're in Lebanon now. Might not be an issue.

No i didn't modify the KJ at all it's still on its standard tune since it came.
i had it for 2 years and it have ~180K KM - the rear and front fluid dif are in good condition, O2 Sensors are in good shape i think but sometimes engine light trigger and say (High Voltage) i think its because of the high gas pressure coming to it, about engine oil we i use 10w 40.

 

[ZiadKiwan]

Ok so converting... it gets around 9mpg mixed 14mpg highway. That is slightly lower but not out of the range of possibilities. What type of plugs did you put in? Could you specify but what you mean changed engine oil type? How does the air filter look?

Also I see you are in Lebanon. What do the highways look like there? What is the typical speed you are traveling and elevation?


Edit.. Dude beat me!

The Types of plugs are Champion - i changed the Engine oil from castrol to another type i don't remember its name now. air filter is clean i keep an eye on it always. we don't have very high speed highway max you can reach is 120KM/H

 

[ZiadKiwan]

I'd check tire pressure (I know it's sounds obvious), brakes may be rubbing somewhere, make sure you used plain old copper core spark plugs, clean air filter, proper alignment...soooo many things that could be the issue

tire pressure is good 33, how do i detect if my brakes are rubbing ?, anyways i don't think they are but i just want to make sure

 

[ZiadKiwan]

i just forgot to mention, when i drive in high elevation road, i feel like the jeep lost it's power like it keeps switching between 2nd and 3rd gear i don't think its normal for an engine with that power right ?

 

[uss2defiant]

MPG also depends on road conditions. Sounds to me like you drive the jeep in hilly areas.

 

[ftaa]

this sounds normal to me lol but the higher altitude you breathe differently so does the jeep . could be messing with the air fuel mixture but i assume the pcm would adjust

 

[tjkj2002]

When driving at higher altitude you will loose power thus loose mpg's,nothing can change that.Your engine oil weight is another factor,for hot weather year round you can use 10w-30 but should stick to 5w-30.10w-40 is to thick and will rob mpg's,more so when the temps drop.

 

[LibertyTC]

Extra MPG can be found by: Using a full synthetic engine oil 5w-30 like Mobil1 EP (extended performance) or Penzoil platinum (made from natural gas) 5w-30
Bump the tires pressure up to 35-36.
Get all extra junk/weight out of the Jeep.
Larger, heavier tires can rob mileage and re gearing 4/10s then needed, restores mileage.
Rear diff servicing should be done every 20 k miles! and if you have a posi or Trac-lok rear diff in there, you must add a posi or 4 oz of mopar limited slip additive #MS- 10111
The rear diff requires 75W-90 or 75W-140 if pulling a trailer.
Turn off the overdrive (switch on side of auto shifter knob) when climbing hills to prevent roaming from 3rd to 4th.
Other than that forget gas mileage, and carry your charge card to keep er filled.
After all this is a fairly heavy SUV that gets a 4WD job done well.
This aint No light weight Honda were talking about here! :gr_grin:

 

[ZiadKiwan]

i just wanted to make sure that my car gas mileage is like all other KJ's thank you guys