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Help with Lousy Gas Mileage
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=88&t=80352		 Page 1 of 1
Author:  wildemt [ Mon Oct 06, 2014 5:53 pm ]
Post subject:  Help with Lousy Gas Mileage
Looking for any constructive input:

Since buying my KK a couple of months ago, I have been averaging 14mpg. It is stock, minus some skid plates. I do not hotrod off of starts and drive conservatively. My highway/town is about an even 50/50.

I don't have any delusions of crazy great mileage from the Jeep... But I would like closer to 17 or 18mpg.

Where would you start? The KK is still under the full factory warranty.
Author:  lfhoward [ Mon Oct 06, 2014 6:54 pm ]
Post subject:  Re: Help with Lousy Gas Mileage
How many miles? I would try changing the spark plugs (which should be done every 30K), changing the engine air filter, and running a bottle of fuel injector cleaner through your next tank of gas. Try to "blow out the cobwebs" with some aggressive accelerations onto the interstate, getting the RPM's above 4K several times. If that doesn't do it, you could try a throttle body cleaning and changing the PCV. None of these are very expensive, so I would start there.
Author:  NAMoulton1 [ Mon Oct 06, 2014 9:09 pm ]
Post subject:  Re: Help with Lousy Gas Mileage
That's worse than me with my 4" lift, bigger tires, and moderate to aggressive driving...you might need to change diff fluids and transmission and transfer case fluids...
Author:  Texasrugby911 [ Tue Oct 07, 2014 12:52 pm ]
Post subject:  Re: Help with Lousy Gas Mileage
NAMoulton1 wrote:
That's worse than me with my 4" lift, bigger tires, and moderate to aggressive driving...you might need to change diff fluids and transmission and transfer case fluids...


I was thinking the same thing... almost. I get worse MPGs (due to all the extras) but 14 for a stock is really bad. I would definitely do the throttle body upgrade, that'll definitely help.
Author:  wildemt [ Tue Oct 07, 2014 6:23 pm ]
Post subject:  Re: Help with Lousy Gas Mileage
lfhoward wrote:
How many miles? I would try changing the spark plugs (which should be done every 30K), changing the engine air filter, and running a bottle of fuel injector cleaner through your next tank of gas. Try to "blow out the cobwebs" with some aggressive accelerations onto the interstate, getting the RPM's above 4K several times. If that doesn't do it, you could try a throttle body cleaning and changing the PCV. None of these are very expensive, so I would start there.

Perfect. Thank you for coming up with a quick laundry list for me. I pulled the plugs. They looked nice and white. And, they are a bit over the .043 gapping. So, I'm off to pick up a new set. Will grab a bottle of fuel injector cleaner at the same time, as I just filled up.

Yeah, the numbers have been PAINFUL to look at. I really am looking forward to getting it up to a reasonable MPG and then dropping it with the accessories I chose. :lol:

Other than the MPG frustration, this has been an amazing vehicle! I get compliments on it consistently. I haven't had a Jeep since my old CJ-5 prior to our third kid coming along... and I didn't get nearly the same amount of compliments off of it (it had a few, um, issues).
Author:  wildemt [ Sun Oct 12, 2014 8:08 am ]
Post subject:  Re: Help with Lousy Gas Mileage
Into my first full tank after the new plugs and fuel injection cleaner. Also bumped my tire pressure up to 35psi.

Things are looking good... Numbers at the end of this tank!

32k miles on my KK.
Author:  LibertyFever [ Sun Oct 12, 2014 9:55 am ]
Post subject:  Re: Help with Lousy Gas Mileage
There's a number of things that can affect gas mileage.
And of course there's the fact that most Jeeps (except for the Compass & Patriot) aren't built for good gas mileage.

You've been given some good tips already. New & correctly gapped spark plugs and properly inflated tires is a good start. Summer tires roll easier than AT's. Roof racks & baskets and light bars kill gas mileage too.

Just how are you calculating your gas mileage? And are you running on stock sized tires?
If you aren't running on stock sized tires than your speedometer and your gas mileage calculations will be off.

I have an 04 KJ with the gas 3.7 L engine and I only get about 21 MPG.


Sent from my iPad using Tapatalk
Author:  Gageraid [ Sun Oct 12, 2014 10:44 am ]
Post subject:  Re: Help with Lousy Gas Mileage
wildemt wrote:
Into my first full tank after the new plugs and fuel injection cleaner. Also bumped my tire pressure up to 35psi.

Things are looking good... Numbers at the end of this tank!

32k miles on my KK.


Good job! I hope you're up to at least 16 when you report back! :mrgreen:
Author:  ross [ Mon Oct 13, 2014 10:26 am ]
Post subject:  Re: Help with Lousy Gas Mileage
On my 2WD 08 gasser my last tank was 22MPG, mostly highway. I normally get 16-17MPG in the mostly city environment (probably 80% city/20% hwy) I usually drive in.

After driving style, tires are the number one thing. Air pressure, and type of tire make a huge difference. I have kept the same brand and size tires that came on the vehicle from the dealership.

Weight of crap in the back might be a place to look. I basically carry nothing around with me most of the time. If you have a bunch of tools, people, luggage, whatever in the Jeep, having to get the higher weight moving at every stop light might be costing you gas.

Aerodynamics aren't the greatest. It's a brick pretty much. It makes more a difference on the highway, where once you get to highway speed, you're going to be paying more in fuel for each additional MPH. Possibly if you drive slower on your 50% highway portion, you'd pick up some MPG.
Author:  wildemt [ Tue Oct 21, 2014 3:34 pm ]
Post subject:  Re: Help with Lousy Gas Mileage
Alright! Good news from the fill-up yesterday. The mileage crept up to 16.35. That was a true 50/50 tank (highway/city) with just a bit of 4WD mixed in.

My question now: Can I run another fuel cleaner treatment through it? I'm assuming that this hasn't been done for some time and doubling-down may yield more improvement. Thoughts?
Author:  tjkj2002 [ Tue Oct 21, 2014 3:53 pm ]
Post subject:  Re: Help with Lousy Gas Mileage
wildemt wrote:

My question now: Can I run another fuel cleaner treatment through it? I'm assuming that this hasn't been done for some time and doubling-down may yield more improvement. Thoughts?

Just pouring something in the gas tank does not clean much of anything but the top of the intake valves.A fuel induction cleaning is what is needed,cleans the whole intake system.

If you buy gas at a quality gas station it already has some cleaners in it(more for higher grades) so adding anymore then what is already there more then say every 6 months can reduce the life of the cats.
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