Gas Mileage...don't laugh

JFWolverine

JFWolverine

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Joined
Jun 7, 2021
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12
Location
Georgia
Alright. I have a 2011 JK. I've owned many Jeeps so as always owning a Jeep is an endeavor of love...it's not a Honda...I get it. And no..I don't expect 20mpg. But hear me out....

My Stats:
2011 JK Unlimited
33" tires
6 Speed Manual

I get 15 mpg.

This is what I've replaced in the last year for various reasons:
  1. New plugs
  2. New plug wires
  3. New EGR
  4. New Fuel Pump/Sending unit
  5. New TIPM
  6. New fuel injectors
  7. regularly changed oil
Again..I realize I won't get 20mpg with a lift and 33" tires...but I feel like 33" tires aren't "large" for a Jeep.

Do any of you guys/gals have some secrets to getting more around 17mpg? And no, we don't dog it...it's a 3.8...it's already a dog.
 
Did you recalibrate your speedometer when you put the taller tires on?

I have same engine and trans but stock tires, do mostly stop and go driving. Half city and half county driving.

According to my dash gauge I average around 16 to 17 mpg's and one time I took a 100 mile round trip and got about 17.5.

Not sure how accurate the dash gauge is compared to hand calculating it.
 
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I doubt if the EGR does much for MPG's, but maybe it does since mine is deleted and gets better mileage.
 
On my way to work (highway), I get 20mpg (sometimes 21) running 35s, 3.6l, 4.10 gears, and an automatic.

My MPG went way up when I put my snorkel on.

Edit: check via dash and by old school calculation.
 
So, how was the calibration done? If you simply entered a 33" tire diameter into JScan or a ProCal, it's not accurate. You should really measure the height of each wheel/tire from the ground to the top of the tire, figure the average and use that. Just plugging in 33, when it's really closer to 32 is going to throw it off.

Do you know if the JKU was re-geared at any time? When you get to cruising speed on the highway are you easily running in 6th gear or are you having to downshift at the slightest incline?
 
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I found the best way was with my Garmin, GPS doesn't lie. I entered it in and went for a drive and it was off some so I changed the setting and got it as close as possible.
 
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I took my hood bumpers off recently. Got some 1/2" Hillman plugs at Lowe's, popped 'em in.
I'll bet that improved my gas mileage by about .0003 mpg.
 
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It doesn't sound like you're too far off the mark for gas mileage. I have a 2008, 3.8l, auto trans, 33 BFG all terrains. I run them around 33 psi cold. My average is just above 16 mpg with mostly city driving. That's based on what the dash gauge tells me. My Sahara has 3.73 gears, no armor, hard top. I run regular gas, which is 85 in Colorado at 7000 feet above sea level.
 
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Anybodyhome said:
So, how was the calibration done? If you simply entered a 33" tire diameter into JScan or a ProCal, it's not accurate. You should really measure the height of each wheel/tire from the ground to the top of the tire, figure the average and use that. Just plugging in 33, when it's really closer to 32 is going to throw it off.

Do you know if the JKU was re-geared at any time? When you get to cruising speed on the highway are you easily running in 6th gear or are you having to downshift at the slightest incline?
Click to expand...
The dash says I get 17 but I never pay attention to that...always calculate it old school.

And I set the tire size using Jscan.

I'm not sure if it was regeared as I bought it used about 3 years ago. On the highway I run it in 6th and do have to drop it to 4th on bigger hills.
 
IndominusHuman said:
On my way to work (highway), I get 20mpg (sometimes 21) running 35s, 3.6l, 4.10 gears, and an automatic.

My MPG went way up when I put my snorkel on.

Edit: check via dash and by old school calculation.
Click to expand...
So while I do most everything on my own with my vehicles I've never regeared. How much would regearing run on average?
 
JFWolverine said:
So while I do most everything on my own with my vehicles I've never regeared. How much would regearing run on average?
Click to expand...
So, you mentioned the Jeep is lifted with 33's on it. Was thinking maybe the PO had larger wheels/tires and possibly had changed the rear end for off-road purposes.
Use this to find out what the Jeep came with (build sheet): https://www.vindecoderz.com/EN/Jeep

A re-gear could go anywhere from $700-$2k, depending on shop and how crazy you want to go.

Oh, and along with removing the hood bumpers, I also removed all the Sahara decals from behind the front fenders. Gives it that "manscaped" look.... I'm sure that also improved my gas mileage. You know, weight and drag.

1630699332417.png
 
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Lately with all the mandatory OT at work the only driving I do is 2miles there and 2 miles home in town. Rocking 12 mpg according to the dash. 08 jk Sahara
 
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Anybodyhome said:
Oh, and along with removing the hood bumpers, I also removed all the Sahara decals from behind the front fenders. Gives it that "manscaped" look.... I'm sure that also improved my gas mileage. You know, weight and drag.
Click to expand...
Good on removing the decals. They cause major drag for sure. On the other side of the coin - I don't know what this will do for gas mileage, but the HP gains are real.

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I haven't calculated my mpg the old fashioned way but my dash says 17.1mpg. I have a 3.6ltr auto trans with 35's on a 6" lift. My build sheet say 3.73's but it's actually 3.21. I'm sure my mpg will decrease in a couple weeks when the 4.56 gears go in.
 
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