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Discussion Starter · #1 ·
Okay I'm new to jeeps. And new to this forum stuff so take it easy on me. With that said I need help I'm totally lost on what to do next!

I have a pretty much stock 1998 jeep wrangler tj, 2.5L 5speed 4x4 144,000 miles NO check engine light! Pretty much stock. No big tires or lift

When I bought with in the first tank of gas I noticed it got VERY poor gas mileage! I burn up a quarter tank in about 25 miles!!!

So I figured okay it needs a tune up bad! So I changed the oil, spark plugs, wires, rotor and cap. And the gas mileage didn't improve.
So I got a AEM brute force cold air intake, once again no improvement!
So I got a Airaid throttle body spacer, with no improvement! A friend tolde maybe my CAT or my muffler was bad!
So I got Pacesetter headers, Magnaflow Cat, and Magnaflow Cat back.

STILL NO improvement! I have no idea whatelse to check an or change!!!!

Please someone for the love of god help me!! Gas prices the way they are this is chewing a big hole in my pocket every week to and from work!
 

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Discussion Starter · #2 ·
One tank of gas gets me about 87-113 miles! That's from over flowing to gas light coming on! There is NO Leaks in the fuel system! And I don't think the brakes are hung up cause I don't smell them or hear them! So I have no idea what it could be!
 

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i have a 98 jeep as well but jeeps in general just have poor gas millage
i believe the 98 four cylinder as 14-15 mpg on the city
 

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113 miles out of a 15 gallon tank on your 98 equals about 7.5 mpg...something is definitely wrong, you should be getting about 17-18 mpg out of a stock 4 banger.

Have you replaced your 02 sensor yet? If not give that a try.
 

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You have a legitimate complaint. An owner who is getting 14mpg and higher has no complaint and I'm going to keep up with this thread to see how it goes for you. I'm surprised that it doesn't burn your eyes a little when you stand near the exaust pipe.
 

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Discussion Starter · #6 ·
No I haven't replaced the O2 sensors yet, I figured they were okay because I didn't have a check engine light, now I have the one before the cat unplugged because it's about 2 inches too short with the pacesetter headers. So when I replace that one, I'll just do them both! Could it be anything else? Fuel injectors? But wouldn't it smell rich if it was those?
 

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Corey_mclinko said:
One tank of gas gets me about 87-113 miles! That's from over flowing to gas light coming on! There is NO Leaks in the fuel system! And I don't think the brakes are hung up cause I don't smell them or hear them! So I have no idea what it could be!
The gas lights are notorious for being skewed. Mine comes on at about 180 miles and I can drive another 60-70 miles before I actually put any in. When you fill it up, the question is how many gallons does it take? If only 7 or 8 no big deal just ignore the light. You could carry a gas can with a couple of gallons in it and just see how far you can go once the light comes on. I don't worry about my gas gauge, only the number of miles since fill up.
 

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Discussion Starter · #11 ·
Yea I guess I could try that! I had thought about the gas gauge being messed up, an honestly I haven't really payed attention to how many gal. I put in, I just know it takes about $40 to fill it, and I'm dumbing 20 in it after about 30 miles.

Right now the gas gauge is at half a tank, with only 57miles.

I plan on 35inch tires and a 4 inch lift. But with the gas milage I'm getting I'm not sure I'll do that! There is a girl at the local autozone that has a jeep with a Chevy V8 and she gets better gas mileage then me! LOL
 

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Discussion Starter · #12 ·
Let's say I get 10 miles per gal. With 70 miles on this tank, It should fit 7 gals of gas give or take right. But I should be getting 15-18 miles per gal. And if that's the case it should fit 5 gals of gas give or take. Does that sound about right?

I'll check it out when I fill up before work!
 

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Yeah if you've only been 70 miles since fill up, go fill up again, it should be around 5 gallons or so, mine would only need 4. Just dont let your gauge fool you into thinking there isn't gas in there. After this fill up, drive it down well past where the light comes on. Just be prepared with a can for backup just in case. If you are getting less than 10mpg and your engine runs good, there is something amiss....
 

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You should start by filling it up, make note of the mileage on the odometer.
Run it through a tank of gas and again make note of the miles on the odometer.

Subtract your starting odometer reading from your ending reading.
That's your total number of miles driven.

Now, divide that total number of miles driven by how many gallons of fuel you put in the tank when you filled up the second time.

That will tell you what your ACTUAL gas mileage is.

Otherwise, it's just a wild assed guess.
 

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How are you checking your gas mpg? They sell some ob2 plug ins that will correctly monitor which is what I plan on getting. Currently I know I'm at most getting 10mpg, that being said I'm running 33s with 4.56 gears so my rpms are very high, I actually managed to shift straight into 2nd unless I'm going up a nice hill. So in my case if I put 35s on I will get better mpg, which is what I plan on doing
 

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you should start by filling it up, make note of the mileage on the odometer.
Run it through a tank of gas and again make note of the miles on the odometer.

Subtract your starting odometer reading from your ending reading.
That's your total number of miles driven.

Now, divide that total number of miles driven by how many gallons of fuel you put in the tank when you filled up the second time.

That will tell you what your actual gas mileage is.

Otherwise, it's just a wild assed guess.
x2..

This is the best way to get an exact figure..
 

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3025826 said:
How are you checking your gas mpg? They sell some ob2 plug ins that will correctly monitor which is what I plan on getting. Currently I know I'm at most getting 10mpg, that being said I'm running 33s with 4.56 gears so my rpms are very high, I actually managed to shift straight into 2nd unless I'm going up a nice hill. So in my case if I put 35s on I will get better mpg, which is what I plan on doing
OBD II monitoring isn't a good option for the 98 Wrangler. It doesn't have all of the required PID's installed for electronic monitoring. That didn't happen until 2003 model year IIRC.
 

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Susiee said:
i have a 98 jeep as well but jeeps in general just have poor gas millage
i believe the 98 four cylinder as 14-15 mpg on the city
My jeep 2005 gets like 17 mpg and my wifes new sahara is like 19 mpg but it has this new feature that you can use ..like economy version of this new engine ..50$ for mine lasts like a month...
 

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