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-   -   bad gas mileg (http://www.wranglerforum.com/f218/bad-gas-mileg-141860.html)

87jeeper 02-23-2012 11:35 PM

bad gas mileg
 
94 yj 2.5 on 31s i,v changed the oil regulary and changed the air,oil,and fuel filters. im geten 15 to 17 miles to the gallon. does any body know whats up this thing?

87jeeper 02-23-2012 11:38 PM

allso i,v done fuell ijecter clener and made sue the tires were at proper psi

rebelBullDawg325 02-23-2012 11:40 PM

that sounds about right. jeeps are very un aero dynamic and the small engine works to push it down the road.

Wrangler06 02-23-2012 11:42 PM

honestly, its a jeep..
not being rude at all i promise but this question is asked atleast twice a week...the 2.5s are known to get bad gas mileage with bigger tires..its the 31s most likely..15 to 17 is not bad for your set up..if you have changed oil air and fuel filters,, try plugs and wires but really not much is going to help...keep all of that up to date, make sure to keep the throttle body clean and use good gas and properly inflated tires, thats really all you can do man

87jeeper 02-24-2012 12:07 AM

hey thanks alot guys.

natax 02-24-2012 12:11 AM

Hey I have a 95 Rubicon Express with 33's and I get decent gas mileage, I filled it up when I first got it and have put about 50 miles on it and my fuel gage has just gone a tick below the F. I know the gage works just fine as I checked everything out. Maybe I am lucky, but so far I am surprised with how well the gas is on it, specially with a 2.5 and 33's.

87jeeper 02-24-2012 12:41 AM

how many miles?

natax 02-24-2012 12:42 AM

That right there is probably the kicker, mine is about to hit 90k miles.

BT 02-24-2012 12:49 AM

@87jeeper Dude I'd be stoked if I was getting the same mileage as you! I am running a '91 4.0 I6 HO with 32X11.5 BFG AT's. I get about 11 and a half to 12 MPG.

Xpress 02-24-2012 01:07 AM

Your MPG is right in the usual range. Jeeps don't get anything over 18-20mpg on a good day.

Do a full tuneup and you might gain about 1mpg, but at least the engine will run like new.

natax 02-24-2012 01:12 AM

Quote:

Originally Posted by bta2011 (Post 2068712)
@87jeeper Dude I'd be stoked if I was getting the same mileage as you! I am running a '91 4.0 I6 HO with 32X11.5 BFG AT's. I get about 11 and a half to 12 MPG.

I am running 33x12.5 MTs as a DD and I get the same if not more as 87jeeper.

rebelBullDawg325 02-24-2012 09:19 AM

gears could also be the difference

Peepers 02-24-2012 09:25 AM

Also is your speedo calibrated for the 31's? You could be traveling farther than you think you are.

bmac6324 02-24-2012 10:08 AM

I estimate for every mile it says I add ten percent, doing the mile self cal on the road I was hitting the marks at .9 mile on odometer, I am also a 2.5 with 31's. So I average about 160ish miles for 10 gallons, add 16 to that for the tenth difference, so my average mpg is around 17-18. Just try it out if you see a mile by mile road markers and see what your is at.

Xpress 02-24-2012 11:42 AM

31" tires would offset the speedometer by 10%, and since it's a linear number, every 10mph you add 10%. So 10mph really is 11mph. 40 mpg is really 44mph. 60mph is really 60mph, and so on and so forth.

ChiliJeep 02-29-2012 01:57 PM

Quote:

Originally Posted by Xpress
31" tires would offset the speedometer by 10%, and since it's a linear number, every 10mph you add 10%. So 10mph really is 11mph. 40 mpg is really 44mph. 60mph is really 60mph, and so on and so forth.

Is that for all jeeps? Or just a certain type?

Xpress 02-29-2012 04:59 PM

That's for any vehicle that has 28-29" tires as stock, and is now running 31" tires. Your speed is off by 10-11%.

ballistx 02-29-2012 08:20 PM

6.9%
 
Actually it is 6.9% more with the 31's than the 29's.

Just filled mine today, all town driving with one short, in-town, interstate jaunt, and got 16.46 mpg. That is with totally stock and 235/75R/15's instead of 225/75R/15's which are extremely close in diameter/circumference.

Yjpower94 02-29-2012 08:39 PM

I'm on 31s with a 2.5 94 also. I read this and was like wait what's the problem haha I keep up with the jeep to and I'm lucky to get 15.

95Mayhem 02-29-2012 09:27 PM

milage
 
I have 95 with the 2.5 on 31's. I put a 62mm 1" throttle body spacer and a cold air system. I was hesitant about the spacer if it really worked, it does help but the mileage didn't go up that much but it's diffidently better on the low and mid range. 14-17 depending:thumb:

benjnewberry 03-01-2012 12:58 AM

I have the small engine and I get about 15 on a good day, 12 if I'm just driving around town. I've heard that the 6-cylinder may get about 22 highway.. Is this true, anybody have the straight 6?

benjnewberry 03-01-2012 01:01 AM

Quote:

Originally Posted by Peepers (Post 2069354)
Also is your speedo calibrated for the 31's? You could be traveling farther than you think you are.

How do you "calibrate" for larger tires? Or is it just adding the 10% to whatever your trip says?:confused:

ChiliJeep 03-01-2012 05:48 AM

Quote:

Originally Posted by benjnewberry

How do you "calibrate" for larger tires? Or is it just adding the 10% to whatever your trip says?:confused:

You can buy a new tooth size for speedo for your size tire, ranges about 35-75 dollars for it depending on where you buy it

busemans 03-01-2012 06:03 PM

i get 9-11 with a 4.5 liter and 225/75/16 tires and no lift. i wish i could get 15

Xpress 03-02-2012 12:03 AM

You have a 4.5L engine in your Jeep?

Details.

darkproximity 03-02-2012 12:24 AM

Quote:

Originally Posted by Xpress
You have a 4.5L engine in your Jeep?

Details.

Probably a stroker with a 258 crank and no over bore

busemans 03-02-2012 04:14 PM

yup.


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