from 19 to 12 mpg...Is something wrong?
JK Freak
Joined: Dec 2009
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From: Boulder County, CO
Thread Starter
JK Freak
Joined: Nov 2009
Posts: 565
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From: Dublin, CA
If you have an AT, then being in the 12's is on the low side, but nothing out of the ordinary.
Few questions:
What size did you input when calibrating your tire size? 35's are rarely ever really 35" tall. Double check your speedo with a GPS. My 35's measured out at about 33.1".
Are you unknowingly driving around with your airconditioner on? If it's set to "Mix" or Defrost, then your A/C kicks in automatically.
Whats your average speed when on the highway? I find that anything over 65mph and I'm burning gas faster than taco bell.
I'm at about a 80% highway 20% local road mix right now and I'm getting 13.5mpg's on my JKU with 35's, armor, lift, kids, etc.
Few questions:
What size did you input when calibrating your tire size? 35's are rarely ever really 35" tall. Double check your speedo with a GPS. My 35's measured out at about 33.1".
Are you unknowingly driving around with your airconditioner on? If it's set to "Mix" or Defrost, then your A/C kicks in automatically.
Whats your average speed when on the highway? I find that anything over 65mph and I'm burning gas faster than taco bell.
I'm at about a 80% highway 20% local road mix right now and I'm getting 13.5mpg's on my JKU with 35's, armor, lift, kids, etc.
No air conditioner on, but that is a good point. I drive around 70 usually on highway, but my mix is about 50% city, 50% highway...so I know that is not helping out the gas mileage either.
Thanks for the input!
JK Super Freak
Joined: Jul 2008
Posts: 1,944
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From: bay area, ca
From everything I've read on this board, it seems that the auto trannies are far far more susceptible to mileage decreases than the sticks.
I keep my tire pressure at 42 and this gives me a mile or so more per gallon and no my tire wear hasn't been affected.
I keep my tire pressure at 42 and this gives me a mile or so more per gallon and no my tire wear hasn't been affected.
JK Super Freak
Joined: Feb 2009
Posts: 1,038
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From: Lancaster County, PA
Wow, the shop had my 35" BFGs at 38-39 and the ride was more harsh (than now at 30-32) and I cannot see how they would have worn well. The inside and outside nipple thingies were still on the tire after 900 miles?! meaning inside and outside tread blocks were never hitting the road. Not worth 1mpg for me, to chance wearing my tires (pricey - $1400 for a set) incorrectly... Can't say if deflating them to 32 will kill more mileage or not, I just did it yesterday.
JK Super Freak
Joined: Sep 2007
Posts: 1,253
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From: Hamilton, Ontario
I put in some premium fuel the other day and it really boosted my fuel mileage. I dont know if it was because it was better fuel or because it had this crap in it that helps clean up your injectors at the same time.
All, i know is that it gave me more kms on my tank of gas.
All, i know is that it gave me more kms on my tank of gas.
JK Super Freak
Joined: Feb 2009
Posts: 1,038
Likes: 0
From: Lancaster County, PA
I put in some premium fuel the other day and it really boosted my fuel mileage. I dont know if it was because it was better fuel or because it had this crap in it that helps clean up your injectors at the same time.
All, i know is that it gave me more kms on my tank of gas.
All, i know is that it gave me more kms on my tank of gas.
JK Super Freak
Joined: Jul 2008
Posts: 1,944
Likes: 6
From: bay area, ca
I don't see how higher octane gas would give you better mileage since it's likely that you burned less fuel per power stroke due to the lack of temperature/compression to ignite all of it. Must've been a coincidence. The JK engine doesn't have the temperature/compression to maximize that octane's burn ratio.
JK Super Freak
Joined: Feb 2009
Posts: 1,038
Likes: 0
From: Lancaster County, PA
I don't see how higher octane gas would give you better mileage since it's likely that you burned less fuel per power stroke due to the lack of temperature/compression to ignite all of it. Must've been a coincidence. The JK engine doesn't have the temperature/compression to maximize that octane's burn ratio.
And I highly doubt he gained 3-5mpg by switching octanes...
JK Freak
Joined: Jul 2009
Posts: 555
Likes: 0
From: Crandon, WI
I don't see how higher octane gas would give you better mileage since it's likely that you burned less fuel per power stroke due to the lack of temperature/compression to ignite all of it. Must've been a coincidence. The JK engine doesn't have the temperature/compression to maximize that octane's burn ratio.