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Old 08-04-2013, 12:11 AM   #1
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Smile Bad gas mileage

Hello, I'm new to the jeep world and I'm having some problems. Now I have a 06 rubicon with 6 speed trans 245-75-16 tires airaid intake rest of the jeep is all stock. I bought it after I sold my Mini Cooper and I don't regret it at all but I have some concerns. I'm getting around 10 to 11 mpg in town and that just doesn't seen right. I've been an ASE tech for years and I can't figure this out. So far I have replaced the o2 sensors ( all four of them) pulled and cleaned the idle air valve , replaced the plugs and coil boots , cleaned and reoiled the air filter, reset the PCM and still not any better. I heard the some of the jeep and wonky fuel gauge and that it can misread the level in the tank.

I'm open to anything to help fix it thanks shane

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Old 08-04-2013, 03:41 AM   #2
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Welcome! How are you calculating your gas milage? By gauge or by actual gallons?

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Old 08-04-2013, 05:42 AM   #3
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Old 08-04-2013, 09:20 AM   #4
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The way I've been calculating it has been by how many gallons put in for half a tank ( I have a thing about not going under half). I'm willing to admit that I don't know every thing about all automobiles and there are times I get stumped on a repair.
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Old 08-04-2013, 09:26 AM   #5
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cats may be clogged/damaged
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Old 08-04-2013, 11:19 AM   #6
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cats may be clogged/damaged
yea I have not checked those yet
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Old 08-04-2013, 11:27 AM   #7
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I get an average of 14 mpg on my '01 TJ, with an auto trans, 4" lift, 33" tires, and geared with 3.73s. When my wife drives it, she averages 9 mpg. When she used to drive our '00 TJ, I noticed she tried to drive it like our Miata, my fingerprints embedded in the "Jesus" bar will testify to that! While it might be fun, jackrabbit starts and constant heavy acceleration are not condusive to good gas mileage. Driving technique goes a long way when driving a Jeep...
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Old 08-04-2013, 12:03 PM   #8
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IDK im leaning towards the fuel gauge issue
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Old 08-04-2013, 12:05 PM   #9
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The way I've been calculating it has been by how many gallons put in for half a tank ( I have a thing about not going under half). I'm willing to admit that I don't know every thing about all automobiles and there are times I get stumped on a repair.
As long as you calculate it by how many gallons you put in, that's fine. How about how far you go? Jeep speedometers are often off by a few mph and larger than stock tires mess with it too. To get an accurate mpg reading I would fill the tank full, drive a set distance (like 100 miles to a friends house or whatever), refill the tank, and see what you have then.
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Old 08-04-2013, 03:46 PM   #10
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You could use your GPS to calculate milage driven, if you dont trust speeo odometer or tripometer. Also only technic I know is to record the amount of gallons-VS milage driven. (put in gas, @ pump- record how many gallons) drive x miles, put in more gas(at gas @ pump-record how many gallons) do that a few times and simple math = MPG. I would not know how you would use the dash gas gauge to estimate this- even close. My TJ w/4.0L auto w/3.07 gears gets 14-16. That it, no mas- and that is driving easy. It would probably inprove if I put 3.55 gears, even if the engine was turning more RPM-it would probably be more efficient in my case.
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Old 08-04-2013, 06:44 PM   #11
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My 05 was getting bad mileage also. I have the Goodyear mtr with kevlar. I was running them around 30Lbs pressure for a softer city/highway ride. I increased the pressure to 36Lbs and the difference in mileage is very dramatic. Just a thought. Check your tire pressure.
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Old 08-04-2013, 06:57 PM   #12
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My 05 was getting bad mileage also. I have the Goodyear mtr with kevlar. I was running them around 30Lbs pressure for a softer city/highway ride. I increased the pressure to 36Lbs and the difference in mileage is very dramatic. Just a thought. Check your tire pressure.
by running your tires with too much air you will gain some increase in mpg, but you will also be wearing out the center of your tread faster.
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Old 08-04-2013, 07:55 PM   #13
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cmon kids, please don't make a moderator stick you all in a time out!


I get 14 city, 17 hwy. K+n air filter, the rest is stock.
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Old 08-04-2013, 08:15 PM   #14
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Jesus people I thought jeep people were friendly!
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Old 08-04-2013, 08:16 PM   #15
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I don't know if you did any tune up work on it, but cleaning the throttle body couldn't hurt. New air filter too. If you are really getting 10 mpg-avg seems kinda low, then have a dealer stick a sniffer up the tail pipe to check air/fuel ratio, might be able to go from there. I assume you know for sure your check engine light works-and you don't have any fault codes. I worked with a guy that would never fix anything that made the check engine light come.He would just drive it. He would go through the trouble of pulling the insterment cluster and removing the bulb before he sold or traded it in.
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Old 08-04-2013, 08:21 PM   #16
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Unemployed for the last 15 months and only need to drive to the park with my dog for her walk on nice days. May need to sell the TJ and get something that only requires me to buy gas every 60 days.

If I could find a job like I had for the last 31 years and drove 50 miles each way I would go back to filling up every 3 days and make 6 figures again.
Dude that blows, hope you get back on your feet fast. My jeep is not my DD, my F150 is and the mpg is just as bad... Maybe I'll put new tires on the Bike and ride when it cools off, that would save some fuel cost.
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Old 08-04-2013, 08:48 PM   #17
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Hello, I'm new to the jeep world and I'm having some problems. Now I have a 06 rubicon with 6 speed trans 245-75-16 tires airaid intake rest of the jeep is all stock. I bought it after I sold my Mini Cooper and I don't regret it at all but I have some concerns. I'm getting around 10 to 11 mpg in town and that just doesn't seen right. I've been an ASE tech for years and I can't figure this out. So far I have replaced the o2 sensors ( all four of them) pulled and cleaned the idle air valve , replaced the plugs and coil boots , cleaned and reoiled the air filter, reset the PCM and still not any better. I heard the some of the jeep and wonky fuel gauge and that it can misread the level in the tank.

I'm open to anything to help fix it thanks shane
Hello! I have same Jeep, but average closer to 16 mpg with the hard top on. The mpg go down as the fun goes up, meaning it's worse with the soft top and worse still topless and doorless. I'm going to assume you are hard top tho. What plugs and sensors did you put in? Bosch doesn't seem Jeep friendly from my readings. Another, and probably bigger factor is how you drive her. I drive mine like there's a tray of crystal vases on the hood, nice and smooth. Slow starts, slow stops and shifts around 2100-2200. That's during the week. When the suns shining, the tunes pumping, topless, doorless, it's party time my friend, and to hell with mpg, lol. Oh yeah, and 62ish is the magic. Above 63 mpg and she guzzle fuel. Bad. More efficient around 62 IMHO.
I recently found out my speedo reads about 4 mph faster than my GPS at 60 mph. I use a free app called aCar to track mileage and other stuff. Pretty neat. Anyway, hope it helps, good luck!

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Old 08-05-2013, 06:58 AM   #18
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Old 08-05-2013, 08:26 AM   #19
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Oops, on post #17, I meant "above 63 mpH" not mpg, lol.
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Old 08-05-2013, 02:16 PM   #20
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start here.
clean your throttle plate. mine had 12 years of black soot on it.
change your spark plugs, go with bosh platinum 2 or 4, they claim better mpg, <I use autolite>
change your plug rail, less work better mileage
change your air filter, I will recommend a K&N, they claim better mpg
put your soft top on, <less weight to haul>
make sure your tires are inflated to 35 lbs. no more, no less
try a synthetic mobile 1 oil, slipperier oil, better mpg
run a few cans of injector cleaner through your tank, less work, better mpg
try, if you can do it, changing the filter basket on the bottom of your pump. Again, Less work....
suck a can of sea foam through the intake manifold through a vacuum line, little by little. unrestricts the intake
run a few tanks of premium gas through your truck to get the gunk outta the system.
if all that doesn't bring you at least 4 mpg difference, I don't know what to suggest anymore.
This is what I did to mine and I went from 10 city to 14 city, and 14 hwy to 17 hwy
Remember, your driving a cinder block around.

Try doing the cpu discharge, its lengthy, I posted something on it. I went from the crap gas mileage to about what it is now, and I did all that. I think it wasn't too much of a help but noticeable after I have been seriously tracking my mpg.
<maybe I can convince the wife into a 2013 Trail rated JK>
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Old 08-05-2013, 02:25 PM   #21
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start here.
clean your throttle plate. mine had 12 years of black soot on it.
change your spark plugs, go with bosh platinum 2 or 4, they claim better mpg, <I use autolite>
change your plug rail, less work better mileage
change your air filter, I will recommend a K&N, they claim better mpg
put your soft top on, <less weight to haul>
make sure your tires are inflated to 35 lbs. no more, no less
try a synthetic mobile 1 oil, slipperier oil, better mpg
run a few cans of injector cleaner through your tank, less work, better mpg
try, if you can do it, changing the filter basket on the bottom of your pump. Again, Less work....
suck a can of sea foam through the intake manifold through a vacuum line, little by little. unrestricts the intake
run a few tanks of premium gas through your truck to get the gunk outta the system.
if all that doesn't bring you at least 4 mpg difference, I don't know what to suggest anymore.
This is what I did to mine and I went from 10 city to 14 city, and 14 hwy to 17 hwy
Remember, your driving a cinder block around.

Try doing the cpu discharge, its lengthy, I posted something on it. I went from the crap gas mileage to about what it is now, and I did all that. I think it wasn't too much of a help but noticeable after I have been seriously tracking my mpg.
<maybe I can convince the wife into a 2013 Trail rated JK>
not to be a downer, theres a lot of good info but also a lot of that is bad info.

do not use the bosch platinum plugs, they dont run well in our motors
no need to change the coil rail unless a coil pack isnt firing
a new AC-Delco air filter is a great idea, stay away from oiled filters like K&N
use the chalk test to keep your tires at the proper psi, 35 is usually too much
injector cleaners usually dont do anything
filter basket on the bottom of a pump???
running higher octane fuel through a lower compression engine will actually leave more deposits than running regular old 87
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Old 08-05-2013, 03:27 PM   #22
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My 05 was getting bad mileage also. I have the Goodyear mtr with kevlar. I was running them around 30Lbs pressure for a softer city/highway ride. I increased the pressure to 36Lbs and the difference in mileage is very dramatic. Just a thought. Check your tire pressure.

Just dropped my pressure back to 33.
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Old 08-05-2013, 04:23 PM   #23
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Have any of the posted suggestions helped?
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Old 08-05-2013, 04:27 PM   #24
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So I was about to pitch a bitch fit at the gas station. Pulled up, put in 14 gallons, checked my trip odometer, 124.3 miles since I last filled up... Turns out my TJ is having that common gauge cluster connection issue. I was watching my trip odometer and sure enough it didn't move at all, my regular odometer didn't move either. So since this was intermittent and not always an issue my jeeps mileage is not accurate. Just fixed my cluster per a write up in a diff thread and counting miles again.. Wish me luck.


OP, make sure your odometer is working and actually counting miles when you measure fuel mpg. Or use a GPS. My $0.02
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Old 08-05-2013, 06:59 PM   #25
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Why not get a k&n oiled filter? Jw i have one in my jeep ans i like it
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Old 08-05-2013, 07:55 PM   #26
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K and n filters do not stop dirt particulates. They are made for mass air flow and are bad for the motors when off road.
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Old 08-05-2013, 07:56 PM   #27
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Why not get a k&n oiled filter? Jw i have one in my jeep ans i like it
Like mine too.
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Old 08-05-2013, 08:54 PM   #28
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Oh well i live in Florida were fine dust particles are really a problem mostly just red clay, thicker grained sand and some black mud by swamps
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Old 08-05-2013, 10:15 PM   #29
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For reference I have an 03 with 140k miles with 31x10.50 and I get 14 in town and16.5 highway. I do not baby it so I suspect something is wrong but not sure what.mileage seems way low for what you have. Mine is a 4.0 and I live in Florida too. I run 30 psi
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Old 08-06-2013, 07:25 AM   #30
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this dawned on me last night as I was driving also, make sure your brake calipers are not stuck/sticking shut.
....
....
I stand my ground on the K&N. Love the heck out of it.
Do not use it for off roading. It says it will void the warranty in the instructions. This is my D/D. I live in Wisconsin.
The fuel strainer is at the bottom of the fuel sending unit. My bad.... He would have seen it when he pulled it. Lets not split hairs over trivial stuff.
I had bosch platinum 4's in my Jeep for years. loved them
Ran higher octane, no problems I'm not saying run it all the time, just one tank.
Ran Mobil 1 oil, outperformed all others. <and I waited for 6000 miles before and oil change.>
I said all that from experience. I did not say any of that in thought, or wish I had...
No offense.

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