But I have a MPG question. Now I know that a JKU is not the most economic vehicle out there and I have always been a Jeep guy, so here it goes. My JKU is getting about 15.2 MPG all city never gets on the highway pretty much stock. I have a AIRAID intake and flowmaster exhaust. that's it. I cant figure out why its so low. I just changed my diff fluid but and its been about 30 degrees here, I cant think of any reason why it is so low. Any hypothosis' on this. Thanks guys.

 

Sounds about right to me for all city, short haul stop and go. May be the largest, widest, heaviest(?) Jeep ever made. Aerodynamics of a brick. Complete set of additional running gear under the front end.

After installing the FlowMaster and Airaid intake did you disconnect the battery for 10 minutes to reset the programming so on restart the computer would learn how to manage the new setup for best efficiency over the first tank or so?

If so equipped try using the ECO / ECO On prompt, to modify your driving style.

It's trite, but it's a Jeep

 

You should be happy-seems about normal-see what happens when you put on a lift and some bigger heavier tires.

 

No kidding. I was nudging 14 MPG on the Interstate Saturday.

 

humm I get around city (chicago) about 16-17 and on the highway about 20-21 and that based on the Jeeps computer which is not accurate I hear but may give you an idea.

 

So you have made modifications to get more air and fuel through the system. But have not retuned the system to the new flow. And you wonder why your fuel econimy has suffered? You need to purchase a tuner to take advantage of your new flow without wasting fuel and energy. That is why they call it the BIG 3. Air, exhaust and tune.

 

x2... that'll do it...
i have a powerflow exhaust on my 2 door...
and a k and n filter on order...
when it arrives i'll re-tune.

 

Keep in mind that your driving around in something with the same aerodynamics of a cinder block. That should explain it all .

 

Yeah, Superchips is next on the list and I want to get it before I move back to AZ. I read that a lot of guys here are running superchips. What tune is the best for MPG? Like I stated earlier I know that Jeeps are not economic and I have heard the whole "If you want MPG buy a prius" thing before. It just hurts filling up 66.00 a tank, and if I can squeeze 2-3 more mpg out of it I will.

 

Like a sucker I tried a K&N FIPK intake & stainless Borla exhaust on my Toytota Tacoma years back. The only thing they seemed to do was to create more noise.

It reduced torque & moved the powerband to a higher point than I regularly used.

As a result, my MPG really seemed to suffer. I installed the stock airbox again & noticed an increase in MPG & seat of the pants torque.

My hypothosis is that your intake & exhaust mods may be working against you.

I would take off the intake & buy a Superchips programmer. Its really the biggest bang for the buck you will find for the JK, especially if you have an auto trans.

There really isn't any "hidden horsepower" left to find in the JK.