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Discussion Starter · #1 ·
for some reason my jeep is using gas bad my mileage has dropped to 13mpg i tuned it up changed the air filter my driving habits have not changed and nothing about the jeep has changed except the fuel consumption is anyone else having this problem and what is the fix
 

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Discussion Starter · #4 ·
well i guess im not alone i was getting better mileage than 13 but it seems to be avg i know its a jeep i was concerned there was something wrong with such a sudden drop in mpg
 

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my 2.5L gets 15mpg ish on 89 gas with 10% ethanol, but weathers been cold and I warm her up in the morning abit before driving.
 

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My mileage on my 4.0l is terrible as well. Around town probably 11 mpg. I need to tune her up to see if I can get an improvement. She just turned 100k and I bought her used so not sure when last tune up was done.
 

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I notice a steady 1-2 mpg drop every winter in my vehicles. Winter gas? Occasional warming up in the mornings? They both probably have something to do with it. Every late spring the mileage goes back up for me.
 

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No such kind of issue with my 4.0L, '01 TJ. 18 to 20 mpg year around in town. Does go down hill as soon as I hit the highway though, especially if I crank it up to 60+ mph.

I'd have to ask if you are positive you're getting the gas tank COMPLETELY filled. There are MANY topics on here about that kind of stuff. Do a search for gas tank capacity or something similar, and you'll see what I mean.

I know with my Jeep, if I don't get it COMPLETELY filled, the mpg's take a BIG hit!!
 

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How full your fill your tank should not affect your miles-per-gallon at all. Unless your doing some kind magical math based on your horribly inacurate gas guage instead of using your trip/odometer. Gas mileage should be calculated by the mile traveled divided by the amount of gas required to refill the tank (assuming you started with a full tank). And on a helpful note if your MPG has suddenly dropped check your tire pressure and check your engine for codes.
 

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I have a 93 F150 I bought new, from day one I checked the mileage at every tank fill up. It is a good indicator when it drops from what is the normal mpg of 15 that something is not right. It could be anything, plugs, wires, injector or a sensor. Last time it was the number 4 fuel injector. Over time if you keep it long enough you can tell if somethings not right, you can fill it in how it drives or sounds. I don't have it with my Jeep yet, only had it a couple of months. I did find a bad bushing and worn gear on the oil pump drive. It was making a ticking sound, not really affecting drive ability yet. Your mpg decrease could be winter gas as others have said but I would check things out to make sure. Over time when the engine hesitates or coughs you will say that sounds like..... The Jeep will grow on you over time and that experience will make it easier to maintain, notice I didn't say easy. I am tracking the mpg on my 06 Wrangler Rubicon and so far after roughly 3K miles it is getting 15.5 on average per tank. Not to bad, some get better and some worse, its just what my Jeep gets and none are alike.
 

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Last time I checked I got 17.5mpg running back and forth to work in 25 degrees temperature. That was a few weeks ago. Stock tire size and gearing on a 97 4.0 manual transmission wrangler sport. I got something like 20mpg on the highway when I made the 2 hour trip back home from picking it up when I bought it. It had the head replaced right before I got it, so I am sure there are new plugs and the wires look pretty new too. No one seemed to believe me when I mentioned my mileage in another post on here. Guess I got lucky to get a rust bucket with good gas mileage. I am sure my mileage will drop severely when I get some 31 inch tires next month.

What did you change when you tuned it up? Just the air filter? If you changed plugs and wires.... then you may have poor quality wires. Or a poor distributer cap if you changed it. I am not sure if just the air filter quality could change fuel mileage that much.... The quality of spark to the plug is important and that can make a fuel mileage difference. When I replace plugs and wires, I always get OEM parts... I had way too many problems with aftermarket wire sets in the past. I am not sure what is on my jeep right now, they are red wires. I am not gonna mess with them though cuz my fuel mileage is great. My motto is, if it isn't broke, just let it be. I am not sure how bad the spark has to be on a wrangler before it will kick on the check engine light.
 

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When I had AT tires on mine I got about 15-16 on the freeway. When I switched to a MT tire I droped to about 13-14 on the highway. I have also noticed that during the winter when they change the gas formula around here my mileage drops in all my vehicles.
 

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jeepster192 said:
for some reason my jeep is using gas bad my mileage has dropped to 13mpg i tuned it up changed the air filter my driving habits have not changed and nothing about the jeep has changed except the fuel consumption is anyone else having this problem and what is the fix
My 1999 TJ averages at 17MPG.
 

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Winter fuel blends will knock your mileage into the dirt. I just dropped from 20+ to about 17. Same ol' jazz every winter: cut it with alcohol and jack up the price. Then, try to convince everyone that a Prius is what you need to buy, and soon! Those rebates won't last long...hurry in for best selection...
 

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2.5 still gettin 19 <3
 

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Sorry for the obscure reference. The point was that the folks that own the oil fields like Jeeps just as much as we do, but for a different reason.
 
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