New JK / MPG & Lift Question -
LinkBack Thread Tools
post #1 of 8 Old 08-08-2010, 07:31 PM Thread Starter
Registered User
2007 JK Wrangler 
Join Date: Aug 2010
Location: Los Angeles, CA
Posts: 74
New JK / MPG & Lift Question

Hey everyone! Picked up a used 2007 JK Sahara Unlimited last week and boy do I love it! It's got (I believe) a Rough Country 6" X-Series lift. I just put new 35" BFG KM2s on her as well. Few questions if I may from you experienced JK guys/gals!

MPG / Performance
I've been reading a lot of posts about the Superchips Flashpaq etc. on improving performance and mpg. Below is what my JK is running with and without OD.

70mph @ 2850rpm in 4th gear

70mph @ 2000rpm in 3rd gear (downshifts constantly)

I've read A LOT of people have problems with the tranny shifting up and down all the time when hitting the slightest of inclines with OD ON and I'm having the same issue. So I tried turning OD OFF and you can see what my RPMs are above. It's more more stable and I don't get the constant up and down shifting, but I need to know am I running too high rpm to be getting decent milage, or is that a god range? Do you know what gearing I might have? I'm thinking it's 4.10 but feel it might not be stock.

I don't think I'm getting the correct odometer/mpg readings either because of the 35" tires, I don't think the original owner get it re-calibrated but I can't tell....

Rough Country Lift
I think I have the 4" or 6" X-Series lift but really am not sure and there's no information from the dealer on any of the aftermarket stuff. Can anyone tell by the pics if it's the X-Series or regular? This lift is pretty gigantic so I'm wondering if I can adjust it if it's the X.






Anyway, thanks in advance for any help! Just trying to figure out more about what I have hear. I love this beast. Just need to get it tuned to run better.

aermotor is offline  
Sponsored Links
post #2 of 8 Old 08-08-2010, 08:29 PM
Registered User
JK Wrangler 
Join Date: Apr 2009
Location: Hayden
Posts: 2,739
Not sure what type of lift it is by looking at it, but size wise I am going to guess 4" just by where the tires are sitting in the fenderwells.

Not sure about the gears, but you could contact Chrysler for a build sheet and see what was installed. Another way to tell especially if they are aftermarket gears is by doing what is detailed in this thread.

The answers to some of your other questions might be here.
McKBrew is offline  
post #3 of 8 Old 08-09-2010, 05:18 PM Thread Starter
Registered User
2007 JK Wrangler 
Join Date: Aug 2010
Location: Los Angeles, CA
Posts: 74
I looked through most of that and didn't find many answers to my specifics of 3rd gear vs. 4th gear. Not sure if running 2900 in 4th instead of 2000 in 3rd is better for milage.
aermotor is offline  
post #4 of 8 Old 08-09-2010, 09:06 PM
RockyClymer's Avatar
2008 JK Wrangler 
Join Date: Apr 2008
Location: Palmer Lake
Posts: 4,851
I noticed that it appears the vent tube to your rear differential/axle is hanging down in the last picture you posted...needs to be relocated higher up with the original clip. (It is that rubber tube with the white plastic tip in it).

08 JK 23S - Colorado Jeep Club No. 204
Too much to list - see my profile for details on build
16 JK Rubi with all the trimmings
NRA Life member
"It takes a special kind of stupid to believe criminals will follow gun laws."
I do not consider myself a smartass. I point out the obvious, search for the truth, and speak fluent sarcasm. I am, by experience, an accomplished curmudgeon.
RockyClymer is offline  
post #5 of 8 Old 08-09-2010, 09:18 PM Thread Starter
Registered User
2007 JK Wrangler 
Join Date: Aug 2010
Location: Los Angeles, CA
Posts: 74
Ahh yes thank you! I saw that too and wondered what it was, dealer (Chevy) had no clue, bah! It looks like it's snapped off so I'll take a look. It's under Aut Nation warranty and I found some other stuff wrong with it, so if I can't just plug it back in I'll have them fix that.
aermotor is offline  
post #6 of 8 Old 08-10-2010, 01:09 AM
Registered User
2006 TJ Wrangler 
Join Date: Jul 2008
Location: Southwest
Posts: 2,189
The Superchips will definitely help to some extent in that it will move the trans shift points to where they should be for your tire size, while also correcting your speedometer and odometer, resulting in your dash calculated fuel economy being more accurate.

However, for you to get back to close to stock performance levels with that lift and tires, 5.13 gears are required.
asknight is offline  
post #7 of 8 Old 08-10-2010, 08:17 AM
Registered User
2009 JK Wrangler 
Join Date: Jul 2005
Location: Columbus, Ohio
Posts: 580
If you're not sure about the speedo being accurate, might try comparing it with a portable GPS. If you need to correct it, the AEV Procal and Superchips will do the job.
Blu-Jacket is offline  
post #8 of 8 Old 08-10-2010, 08:31 AM
Registered User
2008 JK Wrangler 
Join Date: Oct 2008
Posts: 7,223
These guys have it pretty well tagged for your problems and I've looked at this several times--just noticed that--

The brake lines appear to be streched, at "REST", whick means that your first real "Flex"could be areal problem and

The rear brake lines, besides being streched to far, are rubbing against the swaybar and thats DISASTER, along with the strech !!

checkitout !!

Good luck


Yellow Jeep No. 683

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

JIMBOX is offline  

Quick Reply

Register Now

In order to be able to post messages on the forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
Lift/Tires question and Cleaning soft top & engine question Bryan_16 TJ Wrangler Technical Forum 16 05-19-2012 03:25 PM
Tryin to figure out how I'm running 33's. Lift or body lift question. dm33buckeyes TJ Wrangler Technical Forum 21 08-14-2011 04:06 PM
Stupid question. Anyone ever fab anything to lift rear bumper after doing 1" lift blackruby56 TJ Wrangler Technical Forum 11 09-11-2009 01:15 PM
body lift or suspension lift, no this isnt a stupid question!! lumpster TJ Wrangler Technical Forum 5 05-11-2009 09:19 PM
Kinda newb lift question-lift springs signal34 TJ Wrangler Technical Forum 2 08-05-2008 07:56 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome