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-   -   Horrible Gad Mileage (http://www.wranglerforum.com/f282/horrible-gad-mileage-141454.html)

arizonaTJ 02-22-2012 10:52 AM

Horrible Gad Mileage
 
Hey there everybody, I just got my jeep about a week ago, and I bought my first full tank of gas for it a couple days ago, it took about 12 gallons. Then I reset my trip odometer, and I only got about 150 miles out of the tank before I had to fill up again. It is a 4 cylinder and I do a lot of highway driving and my car runs about 3000 rpm at 65 mph, it has a 1" lift and 30 inch tires, so nothing too dramatic, would rehearing help this problem? If so, what should I gear to?

Thanks in advance!

guncrazy72 02-22-2012 11:02 AM

Not sure about gear size for the 30s but for 33s the most popular is 4.10s if you have a auto and 4.56 gears if you have a manual. Your RPMs should drop some but not to much with a gear change. You might want to try and do a tune up on you Jeep. Air filter, fluff ect....

Redsand 02-22-2012 11:02 AM

jeep gas gauges are not exactly always right, and when the light comes on you still have a few gallons left. jeeps just dont get very good mileage anyway

c_goodnow 02-22-2012 11:09 AM

My gauge hits empty around 220 miles, and I would buy 15 gallons or so. Never gave it much thought, until I got a build sheet and hey would ya look at that, its a 19 gallon tank.

The gauges aren't accurate, so check to see what you really have.

Dextreme 02-22-2012 11:12 AM

Quote:

Originally Posted by arizonaTJ (Post 2061427)
Hey there everybody, I just got my jeep about a week ago, and I bought my first full tank of gas for it a couple days ago, it took about 12 gallons. Then I reset my trip odometer, and I only got about 150 miles out of the tank before I had to fill up again. It is a 4 cylinder and I do a lot of highway driving and my car runs about 3000 rpm at 65 mph, it has a 1" lift and 30 inch tires, so nothing too dramatic, would rehearing help this problem? If so, what should I gear to?

Thanks in advance!

The first thing I would do since it is a "new to you Jeep" is replace all the fluids (diffs, tranny, xfer case, engine oil). Then install a new air filter, and cap/rotor if it has it. Also set tires to about 35-40psi. If you milage doesn't get closer to ~15+ mpg, then something else is up.

Redsand 02-22-2012 11:14 AM

Wow, that's a lot of air pressure

SirGeorgeKillian 02-22-2012 11:16 AM

What is your actual mileage? Confirm your spedo is right with a GPS, most of them out now are actually more accurate than the spedo.....

Dextreme 02-22-2012 11:21 AM

Quote:

Originally Posted by Redsand (Post 2061501)
Wow, that's a lot of air pressure

Yes, but I find that I get better gas milage yet I don't run them at the max rated (50 psi) where they jar your teeth on every bump.

SirGeorgeKillian 02-22-2012 11:33 AM

Where is the max pressure? If you are looking at the sidewall, that isnt where you need to be looking. That is the max tested pressure. You are going to wear your tires down quickly that way, and get a rough ride. Any tire pressure related savings you gain will be lost when. You wear out a set of tires 20k miles prematurely.

Dextreme 02-22-2012 11:49 AM

Quote:

Originally Posted by SirGeorgeKillian (Post 2061549)
Where is the max pressure? If you are looking at the sidewall, that isnt where you need to be looking. That is the max tested pressure. You are going to wear your tires down quickly that way, and get a rough ride. Any tire pressure related savings you gain will be lost when. You wear out a set of tires 20k miles prematurely.

Understood...I used the crayon test and find that 35psi works best for my 31's and still get better mpg. I know that 30's "usually" require a few extra PSI due to being a smaller tire. (I keep my 30" spare at 37psi.)

So to the OP...do some searching on here about tire pressure...lots of theorys and also do a search on the crayon/chalk test to determine the psi for your tires. :thumb:

thecheezman 02-22-2012 12:11 PM

Quote:

Originally Posted by guncrazy72 (Post 2061462)
Not sure about gear size for the 30s but for 33s the most popular is 4.10s if you have a auto and 4.56 gears if you have a manual. Your RPMs should drop some but not to much with a gear change. You might want to try and do a tune up on you Jeep. Air filter, fluff ect....


He has a 4cyl. They come stock with 4.10s, youre probably thinking of the 4.0

Jerry Bransford 02-22-2012 12:16 PM

Quote:

Originally Posted by guncrazy72 (Post 2061462)
Not sure about gear size for the 30s but for 33s the most popular is 4.10s if you have a auto and 4.56 gears if you have a manual.

Those ratios are good recommendations for the 4.0L engine but he has the 2.5L engine which comes stock with 4.10 gearing. For a 30" tire and 2.5L engine, 4.10 is a good ratio.

To the OP, drive it a bit more and see what happens to the MPG. You may have been driving it a little extra energetically due to it being new. If the MPG still stays really bad, it may mean you need a new 02 sensor or maybe just a tuneup. :)

MPounds7 02-22-2012 02:52 PM

Quote:

Originally Posted by Dextreme (Post 2061587)
35psi works best for my 31's:

agreed.

sevenservices 02-22-2012 02:59 PM

2 more things to check...

1. make sure your brakes are not dragging. In nuetral, you should be able to push it on level ground with hardly any effort. If there is any drag, get your brakes done.

2. make sure you have a new clean air filter. I saw one packed with leaves once and it really dogged the gas mileage, let alone it would'nt go over 50mph until the leaves were cleaned out of there.

Grateful Parrot 02-22-2012 03:42 PM

Quote:

Originally Posted by c_goodnow (Post 2061487)
My gauge hits empty around 220 miles, and I would buy 15 gallons or so. Never gave it much thought, until I got a build sheet and hey would ya look at that, its a 19 gallon tank.

The gauges aren't accurate, so check to see what you really have.

I bought my TJ used. My gas gauge has never worked since I got the Jeep. My gauge (while running) will never go below a 1/4. I topped my tank off and drove with a gas can all week until I ran out. I got 266 on a tank. Mine almost seems to be where someone did the gas filler mod, but didn't change the sending unit. When I just get to 1/4, I fill back up regardless. But I didn't get the Jeep for mpgs. I got it for the fun.

Of course, you can also do what I did. I found a management job 1.6 miles from the house. I working on biking to work, but it's always more fun to take the Jeep.

KrazyItch 02-22-2012 04:26 PM

Might not help your situation, but im on 31x10.50s with a 3" lift on my LJ (LJ is unlimited correct?). Its not a 4 banger, but the 6 and i get around 13mpg to 16mpg depending on my driving habits... Normally highway im anywhere between 70 to 80mph at around 3k to 3.5k :banghead:

oIIIIIIo 02-22-2012 04:46 PM

I get about 150-160 miles on a full tank of gas. I am running 33's with 4.10 gears, 3sp auto.

The mileage do sux on it.

TOKKIE 02-22-2012 04:52 PM

Since no one has asked. How many gallons did it take to fill the second time(after driving the 150 miles)?

arizonaTJ 02-22-2012 11:28 PM

Quote:

Originally Posted by TOKKIE
Since no one has asked. How many gallons did it take to fill the second time(after driving the 150 miles)?

It took around 12 gallons, but now that I know it's a 19 gallon tank, I guess I could go quite a but further than that

arizonaTJ 02-22-2012 11:31 PM

Quote:

Originally Posted by Dextreme

The first thing I would do since it is a "new to you Jeep" is replace all the fluids (diffs, tranny, xfer case, engine oil). Then install a new air filter, and cap/rotor if it has it. Also set tires to about 35-40psi. If you milage doesn't get closer to ~15+ mpg, then something else is up.

Thanks, I'll do those things and see how that affects my mileage (if at all). Thanks everybody for help!


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