wow, i must have a cataclysmic malfunction somewhere! if i was getting more than 22-24MPG, i wouldnt think twice about lifting my KJ!
also, to answer someone else's question... my CEL was NOT on. my spark plugs were REEEEEEEEAAAAAAALLY bad. i replaced them and my MPG jumped a good amount. im just looking to get back to what i used to get(19-20MPG HWY). if i could regularly get above 20MPG i would pay almost any amount of $ for it to be so.
'04 Jeep Liberty and '67 Jeepster Commando
On trips I can average 21-21.5 at 70-75 no problems
Thats with lots of extra weight, ( Kilby Skid,front and rear aftermarket bumpers, 32 inch tires etc )
of course before I went to 4.10s it was about 14-15 I think
04 Liberty, Kilimanjaro Edition, Rock Lizard RockRails/Roof Rack/Front-Rear bumper,32 inch Goodyear Duratracs,Moabs,4.10s/ 4.25 inch JBA Coilover lift /other goodies
My GF just got back from Kentuky got 26 on the way down with a can of Sea Foam in the tank, 28 on the way home. cruise set at 62 both ways and air off. City driving is about 12 average. She has about 117000 miles.
these guys are right if I was you and there werent any codes showing, check the differentials and transfercase. Check your front hubs theres really no way, without looking close to know when those bearings go bad. They will bring down your milage when they start to drag.
Some good tips here and it's a hot topic in other related threads about plug choices and such. However, one assumption needs tested in ALL these various gas mileage claims; that when you refill the tank to measure what MPG you got, you refilled it to EXACTLY the same level. Because if you didn't then the whole basis of your MPG math is wrong. Maybe today's gas pumps are so consistently well metered that this is not a factor, anyone know? Till proven otherwise, unless you're using a dipstick on level ground to test before and after fuel levels to base your math on, it could be a factor.
Lets say in a 20 gal tank you drive 200 miles then refill it, at some other station and/or pump than you filled it up at (add variations in temperature to this also, a small factor). But at the refill you don't get it filled to the previous level, you're about 1/2 gal short of the fuel level you began at. So the pump trips off with a 10 gal refill and you figure you just got 20 mpg, but in fact, you used 10.5 gallons not 10. You think you got 21mpg but you really only got 20.
Was it windy when you drove? Aerodynamics are huge friction sources and our boxey KJ are not exactly built for low drag coefficients. That could give you a 1-2-3mpg variance easily.
Granted these are minor and don't account for say, going from 20mpg to 14mpg but they contribute.
If these 'tests' are done on the same strip of highway or city blocks in the same exact driving conditions and you refilled the tank the exact amount of gas used, then it's fact. Short of that it's a lot of speculation seems to me.
By the way, our gas mileage sucks too but I discovered it's my wife's foot. When I drive the car it goes about 50-75 miles further on a tank doing pretty much (again, not scientific..) kind of driving mix. As someone said, these are heavy beasts but we love our 2005 with almost 100K on it now, it's been rock solid.
hers the scoops for all of you libertys are heavy vehicles, on lite frame, i opened exhaust , changed air to kn and opened air intake, put in chip got more power, only little bit went up to 20 22 mpg noticed if i stay with 86-87 octane, keep injectors clean and keep foot off pedal helps , i notice when i go to nm and fill up i get better gas mileage, they dont use as much additives as colorado utah and az so fuel does have something to do with it but take it from someone who did all the crap to one just slow down some there great little jeeps will take you any where ive taken it everywhere my cj7 goes even up to 12000 feet in silverton co gas mileage is not its greatest feet, but it has others enjoy them alohas