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Unread 01-30-2012, 02:01 PM   #1
Doubblea
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1999 TJ Wrangler 
 
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HORRIBLE MPG Help

I have a 99 wrangler tj with AEM air intake and banks header, 4.0L, and 3.5" lift with 33x12.5. I drive my jeep like a grandma and i still get around 10 mpg. most of this driving is going 55 to school. I realize i did not buy this jeep for mpg, but honestly 10? ive read of the normal being 15 and good around 20 on this forum. any suggestions on what to check or replace is greatly appreciated.

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Unread 01-30-2012, 02:04 PM   #2
Jrob05
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Lugging the motor kills mileage, Lifts kill mileage, and so does a improperly calibrated speedometer.
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Unread 01-30-2012, 02:05 PM   #3
rlkelley
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i know this is a dumb question but how old is your air filter ? if its several years old and has never been cleaned or replaced it could affect mileage.

also, the lift doesnt help, but you should get more than 10 i would think. has the jeep ever had a tune up ? same factory plugs, wires etc........
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Unread 01-30-2012, 02:06 PM   #4
duhamel17
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Not sure what gears you have, but I have a 3 speed auto with 4.10's and 33's. With this combo I am getting about 12mpg on a good day. I think this has a lot to do with the three speed auto tranny. That is all I now on that. I hear about some people getting 20 or better, but not sure if that is actually possible.
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Unread 01-30-2012, 02:40 PM   #5
schwany01
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i get 10mpg with a 4 inch lift and 33s, stock gears with D44, with 31s for the winter i get 13-15mpg
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Unread 01-30-2012, 02:52 PM   #6
jkiech
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From what I've learned either drop down to smaller tires or re-gear to different gears like 4.56's.
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Unread 01-30-2012, 03:29 PM   #7
Dangermouse
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I used to get that but now it's up to 11 mpg. Sounds normal to me.
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Unread 01-30-2012, 05:49 PM   #8
Doubblea
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First off I would like to thank everyone for the replies. I have 3.07 gears, and the 5 speed ax15. I cleaned the air filter out a month ago when I bought the jeep. I do not know if they are the factory plugs or wires, anyone know what to look for on that?
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Unread 02-03-2012, 04:44 PM   #9
ACRay
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4'' lift, 33'' BFG KM2s, 4.56 gears in my 06 TJ with a 4.0 and an automatic with a correctly calibrated Speedo (GPS checked with 3 different GPS units) and I get almost 19 mpg..... maybe I'm the exception, either way, I win
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Unread 02-03-2012, 04:50 PM   #10
vanek11
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Important...Check to make sure the speedo is correct. I thought the same also but then realized my speedo is about 10% off. I have a 4" lift and 33" tires also. Just calculated roughly yesterday and found to be getting 14mpg in 75% city driving. When I am going 50 I am actually going 55, so assuming that the odometer is also going to be off, meaning if I travel 50 miles I am actually going 55 miles. Someone correct me if I am wrong but if the speedo is off it would be common sense to me that the odometer would also be off. I am happy at 14mpg with the lift and tires and not driving easy.
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Unread 02-03-2012, 04:51 PM   #11
FZY1
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You Drive a Jeep, with the aerodynamics of a brick.
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Unread 02-03-2012, 04:56 PM   #12
hesterj
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I really thought this was a joke....like all the other million same posts here.
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Unread 02-03-2012, 05:17 PM   #13
cjtheodo
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Check your rpms when driving.It seems that to get better gas mileage it needs to be around 2200-2800. There are different ways to get it there.
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Unread 02-03-2012, 05:19 PM   #14
djflyy
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Your problem is the same as every other person that has created one of these threads (scroll to the bottom here and click ANY of the resembling thread links).

- Check your speedometer gear, make sure it's appropriate for your tire size and axle ratio. There's also a speedo swap thread on here, you might be able to get one for free.

- Swap your plugs for new ones. AutoLite is a favorite of many. Get a new distributor cap, and new plugs. Below is a pic of the old ones from my TJ just to give you an idea.

- Make sure your tires are appropriately inflated (read: do not overinflate)

- Check air filter condition

- Re-gear.




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Quote:
Originally Posted by bmosing View Post
Cleaning this thing up is similar to a slightly abused pornstar throwing on a bunch of makeup to try to hide her eternal scars, but I think she doesn't look too bad
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Unread 02-03-2012, 05:21 PM   #15
DevilDogDoc
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Quote:
Originally Posted by Doubblea View Post
First off I would like to thank everyone for the replies. I have 3.07 gears, and the 5 speed ax15. I cleaned the air filter out a month ago when I bought the jeep. I do not know if they are the factory plugs or wires, anyone know what to look for on that?
I have the same setup as you but without the bull**** "power adders", running 33/11.5's and I get 15 MPG all day everyday. Look at tuneup stuff first....
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