Brandon1024

The air dam has been off for awhile so thats not the difference. I am just using the stock tires. And lastly yes 87 octane

jhol111964

I think everyone is convinced, that you've got something wrong. Its an uneasy feeling to see how different everyone's mileage is, with carbon copy Jeeps. It makes me wonder just how consistent Jeep's products are? I'm getting almost 18 mpg all-purpose driving, otherwise I'd be nonplussed with anything less.

Ant

I would suggest checking the e-brake again. Mine seized earlier in the year and the first indicator I had was my mileage dropping. I had a squeek everytime I started moving after it sat for a bit.

I track my mileage every fill so it was pretty obvious something was wrong when I went from about 15l/100km (~15MPG) to almost 20l/100km (~11MPG).
After getting it fixed and retuning my Superchips to the 87 Octane tune I'm around 14l/100km (~17MPG).

I have a stock '08 Rubicon Unlimited. The only thing I did recently was add a MBRP Roof Rack . Hasn't really affected mileage from what I can see.

Cheers,

GearWhore

Have you checked your actual mileage numbers (not just what the computer says)? Your mileage does seem really low. If you haven't, I'd keep a log of actual mileage driven and fuel consumed. I know my computer mileage numbers are usually off by as much as 2-3 mpg.

The stock air-dam (if you still have it and the bumper) will make a pretty considerable difference. I have an 09 JKU Rubi 6-spd with the stock tires and wheels (on spacers) and a 3" TeraFlex lift (closer to 4.5" since I don't have heavy bumpers or my hard top on) and I average 17-19.5 mpg for very mixed driving (live at 7200' and pretty much daily drive through a few thousand feet of elevation change in the mountains, as well as town/city driving, and highway miles). I generally try to be really good with my right foot, but have a couple times a day when I get pissy and stomp on it. Also tow my boat in and out of the water as well, and am off-road usually once or twice a week up in the mountains playing. When I'm just driving on the highway, I can get 21-22mpg if I'm careful and also keep my speed below 65. When I go over 65, I can really notice a difference in mileage.

Good luck with solving your issue!

Brandon1024

Well while out driving last night I noticed that it starts to climb (get into the 11's) but then at the stop light it drops to around 7... So I need to do the number myself and see. the only problem is I'm at college and take months to go through a tank :new: also how do I go about checking the brakes?

ScaleJK4x4

By chance, do you have an Android based phone? There is an AP called "Mileage" in the Market. It is a GREAT ap! Check it out!

Brandon1024

i don't have an android but i have an iPhone... chances are they have an app for it... As for the brakes they aren't that hung up but when I'm at a stop light it doesn't idle forward it stays right in place making me think they could be somewhat.

Doc Holliday

easiest way to track your mileage if your computer is calibrated to all the modifications you have made is to reset your trip after fill up then when you stop to get gas divide your total miles by how many gallons it has taken to fill the Jeep back up with (my jeep's mileage deal was off by anywhere from 1 to 2 miles). I know this is 2nd grade math so don't take offense to my simple minded explanation above. just trying to throw out an idea

Freewill

The Jeep (or any automotive electrical system) will not let your battery run at constant discharge, so any and all electrical draws are supplied by the alternator when the engine is running.

If your lights, engine computers, AC fan, and a stereo demand, lets say, 750 watts, the engine and alternator do all the work required to produce the 750 watts.

750 watts happens to be equal to one horsepower, so with all your stuff running the engine must produce one extra horsepower. On a 210HP engine that's about 0.5 percent more power.

You could loosely interpret this to mean the MPG might go down 0.5 percent with all your electrical accessories running. So, yes, electrical stuff does require some engine power, but it doesn't explain a drop of several MPG.