Poor Gas Mileage

[RobTJ]

In the past 2 weeks my gas mileage has dropped drastically.  I went from getting 15-17mpg to 12. 
It did something similar to this last winter as well,  around the same week too. (right around XMAS). 

I was just curious if it had something to do with the weather,  or because it's a engine with high mileage on it.
And should I be putting adatives in with the gas (ie dry gas / injector cleaner).  Or is there a bigger problem lurking.

 

[HookSetSteve]

I don't think it's the mileage
I don't have high miles and I'm at 12 too

 

[NomadJeep]

Did you use 4WD High in the snow... that sucks gas.  Change tire size, with inproper gearing, that will suck gas.

Your doing great if you get 17 mpg


the 4.0 is a break-in motor.

Here are my 6 cyl specs

03 Rubicon, 30k miles on a good highway week max= 15 mpg

01 XJ, 65k miles on a good highway week max= 17 mpg

94 ZJ, 212k miles on a good highway week max= 19 mpg

The ZJ is by far the best being the motor is just breaking in. :grinyes:

Remember these are highways. so usually it is even less than that...

 

[JeepinMaxx]

1992 4.0 with ~ 90K miles:
17MPG highway
12MPG around town when I let it warm up for 15 minutes

Also, depending on where you get gas - they switch to an ethanol blend in the winter (= less performance and milage)

 

[RobTJ]

Did you use 4WD High in the snow... that sucks gas.  Change tire size, with inproper gearing, that will suck gas.

I knew when I put the 33s on running only 3.73 gears I was going to take a hint on gas mileage.
But it would hold around 15-17.  It's just puzzling why the sudden drop. 

I'm trying to think if I've changed my driving style lately.  I haven't had it in 4wd yet this winter.  And it garaged so it only warms up for about 5-6 minutes on the cold mornings.

 

[Rubi04TJ]

They also add some crap to the gas during the winter months, not really sure when that happens, but gas miliage does fall when it happens.. I can't remember the name of it.


Your still ahead of me.. i get 11mpg all year long

 

[DonnyG]

Your still ahead of me.. i get 11mpg all year long

Zach, you'll get better mileage if you keep all four tires on the road!!! :mad02: :mrgreen:

 

[bigbadwhitey666]

I get around 8-10  :biggrin: 35's and 3.07 gears.

 

[xjmark]

In the past 2 weeks my gas mileage has dropped drastically.   I went from getting 15-17mpg to 12. 
It did something similar to this last winter as well,  around the same week too. (right around XMAS). 

Both times are right around Christmas time huh? :thinking:
Could be a neighbor siphoning gas out of your tank after over extending his wallet buying holiday gifts. :lol:

I never calculated the mileage on my vehicles, but I know it's not good.

 

[massxj]

they start adding "stuff" to the gas in the winter months  this could be what your problem  is       btw  i get anywhere from 10.5 to 11.5  per gal  if im lucky      stock motor  33x12.5  with 4:56 gears  and a stick

 

[Pickle]

If I'm nice on my ZJ with a 5.2 I get 16 only on the highway with 3.73 and close to 31's and about 11-13 in the city.  My XJ with 3.07 and 31's used to get close to 20 on the highway but that went way down.

 

[kakirubi]

Lettin it warm up?  That would do it. :thinking:

Although I kinda like Detours thoughts.  I never knew he was a conspiracy theorist! :listen:

 

[Rubi04TJ]

warming up will effect your gas miliage alot.. for the worse

 

[JeepinMaxx]

They also add some crap to the gas during the winter months, not really sure when that happens, but gas miliage does fall when it happens.. I can't remember the name of it.

Also, depending on where you get gas - they switch to an ethanol blend in the winter (= less performance and milage)

They used to use MTBE (METHYL TERTIARY-BUTYL ETHER) I don't know if they still use it, but it kills milage and power to increase emissions .  I think they replaced it with ethanol. 

 

[jon]

Connecticut stopped using MTBE a few years ago and now adds ethanol.  I beleive that the gas we use is actually E10  (90% gas , 10% ethanol). 

If you have a 4.0 why are you letting it warm up?  when I had the 4.2L I had to let the POS warm up, but now with the fuel injection it never needs it.

 

[PaulW]

If you wanted gas mileage shoulda bought a Honda.....


JEEP

Just Empty Evry Pockket.

Best I ever got was 14mpg.  4.0 ax15 4.10's 32's

 

[Zookie400]

cold air does require more fuel to keep everything stoichiometric.  <---i think i spelled that right :question:

 

[RobTJ]

If you have a 4.0 why are you letting it warm up?  when I had the 4.2L I had to let the POS warm up, but now with the fuel injection it never needs it.

I'm not letting the engine warm up..  I'm letting the cab warm up before I get in it.

 

[jon]

If you have a 4.0 why are you letting it warm up?  when I had the 4.2L I had to let the POS warm up, but now with the fuel injection it never needs it.

I'm not letting the engine warm up..  I'm letting the cab warm up before I get in it.

<cough>  wuss  <cough>

 

[Rubi04TJ]

It effects your miliage when you let it up, becuase your vehicle is not traveling while you do so... becuase gas miliage is calculated by milage divided by gallons, sitting time is not calculated into the equation. make since? so you if you got a full tank of gas and parked it, and let it run till it ran out of gas, you would get 0 miles per gallon.