Holy bad gas mileage!

CTjeeper16 · **Posted:** Tue Jun 26, 2007 11:05 am

Ok, so driving back and fourth (90% highway) this past week, I only got 252 miles on an entire tank of gas. Now IIRC, the tank is 18.5 gallons, so one would figure I used about 18, so that's what, about 14mpg???? That is miserable, especially considering it was highway driving. I'm not lifted, and have 245/70 grabbers and skids.

What could be causing this?

What can I do to improve this? I'm thinking swapping the muffler for some help, maybe a K&N or something along those lines too. Cause if this stays the way it is, I'll seriously need to consider just getting a TJ, because the gas mileage will be the same, but I'd also have a removable top.

Video Guy · **Posted:** Tue Jun 26, 2007 11:17 am

How fast are you driving? Try keeping it under 60 mph. I have the same year and model KJ and same tires, plus a little lift, and I normally get about 270 miles on 16 gal. commuting through the 'burbs. You should be getting about 20 mpg on the highway, unless you're one of those people who cruises at 70 mpg. Your KJ is basically a big box on heavy tires, so it's anything but aerodynamic, which keeps highway mpg down.

I'll tell you straight up: the Grabber AT2 tires will hit your mileage 1-2 mpg, but your mileage, however, seems eceptionally poor. Things to consider:

When was your last oil change?
How old is the fluid in your rear differntial? (My mileage improved when I changed it at 45K miles.)
Have your alignment checked.

Good luck. Let us know what you find out.

KW AV8R · **Posted:** Tue Jun 26, 2007 11:24 am

Keep in mind that some KJs will read empty on the gauge when they still have a decent amount of gas left. For example: when I am reading completely empty I can only fit 15 gal and that is with a 19 gal tank. The best way to figure it out is to fill your tank completely, reset your trip odometer, drive your allotted distance, fill your tank completely, then divided the distance by the number of gallons to get your mpg. I know quite a few know this but I thought I would throw it out for those that don't.

hyedipin · **Joined:** Thu May 11, 2006 10:20 am **Posts:** 1667

No, did you fill up the tank before you started and is that until the low gas light came on?
That's only 15 gallons.

253 from fill up to light will be about 16mpg. That's pretty good..
forget mpg.
I am getting 220 miles to full tank of gas.
If i drive strictly highway, and no flooring, from tank to tank i will get 280 MAYBE!

So stop complaining already.

just kidding, lose the skids and go skinnier tires.

hyedipin · **Joined:** Thu May 11, 2006 10:20 am **Posts:** 1667

^ posted about same time with KW AV8R.. you got the idea..

Jeepjeepster · **Posted:** Tue Jun 26, 2007 11:29 am

Yea, the bigger tire size shouldnt change anything but those aggressive tires will hurt the mpg. I had those tires then switched to the geolander A/T-S and Im very pleased..

How many miles are on the spark plugs?

And you probably didnt use 18 gallons. Ive ran mine till the gauge was pegged on E and I got 17gallons in it, but I have the 19.5gallon tank.. How many gallons did you put in the tank? thats a better way to figure up mileage..

hyedipin · **Joined:** Thu May 11, 2006 10:20 am **Posts:** 1667

what's the deal with the spark plugs, everyone has been referring to them
Only if they weren't so darn dificult to replace.

chefdab · **Posted:** Tue Jun 26, 2007 1:19 pm

The 03's had a 19.5 gallon tank too. When I had mine, the low fuel light would come on with about 3 gallons left. To get a more accurate reading of your mpg, divide the number of miles driven by the number of gallons you put in. There is still a margin of error but it will be a lot closer to your actual mpg. You may be pleasantly surprised when you calculate it this way. Probably more like 16 or 17 mpg.

Dje Ryu · **Posted:** Tue Jun 26, 2007 2:42 pm

one other thing it doesn't look like anyone else has brought up. How much weight do you have in your KJ? tools, etc? I took out one of my tool boxes and gained one mpg. lol. The sliders add quite a bit, also.

Tokyojoe · **Posted:** Tue Jun 26, 2007 3:14 pm

While it is really hard to determine the exact amount of the tank saying it is empty, you can be sure there is about 3-4 gallons of reserve. When I fill up and I am around the ZERO miles left in the tank (according to the EVIC...low fuel light comes on at 20 miles left), I put in only around 15.3 gallons.

If your odometer is correct, just divide total miles by how much you put in. It is still not accurate since you may have had more or less in when you started.

hyedipin · **Joined:** Thu May 11, 2006 10:20 am **Posts:** 1667

Tokyojoe wrote:

While it is really hard to determine the exact amount of the tank saying it is empty, you can be sure there is about 3-4 gallons of reserve. When I fill up and I am around the ZERO miles left in the tank (according to the EVIC...low fuel light comes on at 20 miles left), I put in only around 15.3 gallons.

If your odometer is correct, just divide total miles by how much you put in. It is still not accurate since you may have had more or less in when you started.

Same here. I have 19.5 tank and I can never fill up more than 16 when EVIC says 0 miles to empty and actually driving for about 2-3 miles. Cold Sweats!
However if you stop the Jeep, wait about 2-3 minutes and restart it, you will see that magically you will have "10 miles to empty" on EVIC and sometimes even the low-gas light will turn off! Ahh jeep..

Jeepjeepster · **Posted:** Tue Jun 26, 2007 4:11 pm

When a spark plug is worn or dirty hyedipin(cant see your sig to spell your real name, hehe), it doesnt burn the fuel as efficiently as it would if it was clean and new.

And yes, weight can take the mpg down more than you think. Once you get all the skids, bigger tires, rocker rails, extra people in the Jeep, maybe a sub, hitch, steel rims(if you have them), extra tools and such, you can get over 500lbs of extra junk in the Jeep.

Ive weighed some of the stuff I have on/in my Jeep.

-Me 155lbs
-Engine skid, tranny skid, tcase skid, around 15-20lbs apiece. Gas tank is probably 20-25lbs, ive never weighed it.
-My custom rocker rails are 60lbs a piece and they are lighter than normal rails
-Sub is 75lbs
-Hitch is 65lbs(drawtite)
-Extra tools and such-around 15-20lbs
-Cragar rims with 245/70/16 Geolander A/T-S' 75lbs apiece and the stock 17"chromes with 235/65/17's are 50lbs a piece. Thats rotational mass which has a greater effect on mpg and torque.

thats around 450lbs.

The weight adds up alot quicker than you think it does.

I only use my cragar rims in the winter and really do not notice a drop in mpg or performance. It may kick down into 3rd just a tad earlier than it would with the stock rims.

I can have my rocker rails on and off in under 30min and since I only go offroad 2-3times per year, I just leave those off.

Taking the rocker rails off takes that down to 330 and without the rims its just 230.. Which isnt much at all.

Brigrat · **Joined:** Sun May 21, 2006 6:17 pm **Posts:** 92

I am getting well over 340 per tank, and I fill up at least 1/8th before the light comes on. I average around 20mpg driving 70% highway.

hyedipin · **Joined:** Thu May 11, 2006 10:20 am **Posts:** 1667

Renegades got better aerodynamics! :evil:

Donnie · **Posted:** Tue Jun 26, 2007 4:58 pm

I actually clocked a trip to misquamicut RI, from Northern CT. I was going 75-90 (early morning) the whole way and recieved 19.2 mpg, just avoid hard stops and acceleration and you'll be gold.

Sean150 · **Posted:** Tue Jun 26, 2007 6:13 pm

Someone might have mentioned and I missed it but.....

What is your tire pressure? Is it at the recommended pressure or a little less than that. If they are add the recommended pressure try adding a few extra psi and see if that helps.

steepcreekfreak · **Posted:** Tue Jun 26, 2007 6:33 pm

Donnie wrote:

I actually clocked a trip to misquamicut RI, from Northern CT. I was going 75-90 (early morning) the whole way and recieved 19.2 mpg, just avoid hard stops and acceleration and you'll be gold.

Yeah around town it is the hard stops and starts that kill you mpg.

I often play a little game on my way to and from work. It is all back roads. I reset my evic and try to drive in a way to get the best mpg. I have pulled down days of 22mpg with my wrangler at's! As you can see from my profile my jeep is heavy. I weigh 240lbs myself and I carry tools and associated equipment. I try to roll to stops and accelerate slowly. This not only gets better MPG but your putting less wear on everything in your vehicle. Brakes, engine, tranny, bearings, ecetra.

With my MTR's mounted I have done 20mpg days but if I am in a hurry it can drop to 15-16 MTR's or 17-18 AT's real quick.

I also run my AT's at about 33-35 psi and my MTR's at about 45psi

Oh yeah, I have also found if you have a renny and you drive with the light bar covers open you lose a little especially on the highway. The open light bays cause a little more turbulence and resistance at high speeds I think.

David Jr · **Posted:** Tue Jun 26, 2007 7:37 pm

Last time i went to Hershey Park, which is a straight run down the PA turnpike from NJ, i got 20mpg. And that was doing 80-85 MPH all the way. BTW, i'm still bone stock.

fast1 · **Posted:** Tue Jun 26, 2007 9:23 pm

check your air filter and posibly get your o2 sensor checked my 05 was getting an average of about 26 mpg when my 06 braeks in it should be close

Guest · **Posted:** Wed Jun 27, 2007 3:06 am

hyedipin wrote:

what's the deal with the spark plugs, everyone has been referring to them
Only if they weren't so darn dificult to replace.

it's easy. remove the nuts from the studs in the firewall on the coolant reservoir, remove the retaining nut from the coil packs (5.5mm iirc), and get a 3" extension, universal joint, 3/8 ratchet, 6" extension, and the obvious plug socket.

Pressure wash your engine either while cold or running to get all the gook out of the plug holes first, or use compressed air.

Holy bad gas mileage!

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