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Cool weather mileag
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=1&t=25950		 Page 1 of 1
Author:  Renegade03 [ Mon Oct 29, 2007 10:52 am ]
Post subject:  Cool weather mileag
I an the original owner of an '03 Liberty Renegade with 86,000+ miles. I know from reading this Forum and from my own experience, that fuel economy isn't one of the Liberty's strong points, but I have a question regarding fuel economy. I drive about 18,000 miles a year, much of it for work, so I keep accurate records of my fuel useage for mileage reimbursement. Since my Jeep was new, I have noticed that my Liberty get its best fuel economy during the hottest weather of the year, but as soon as the daytime temperatures drop down below 70 degrees F, the fuel economy drops off too. The reduction is anywhere from 5 to 10 percent (1 to 4 mpg). I am not refering to winter conditions, which may require slower driving; I'm refering to September and October when the roads are dry and the traffic is moving fine. There has been no change in my driving habits over the past fifty-eight months, and yet in reviewing my records, my fuel economy increases starting in May and drops off starting in September.

Every other car I have owned has gotten the same or better fuel economy when ambient air temperature is between 50 and 70 degrees F. It makes sense because the cool air is more dense and provides a bigger result (explosion) from the ignition of the fuel air mixture because more air is packed into the same space. My Liberty is just the opposite. Can anyone tell my why?
Author:  JPaul [ Mon Oct 29, 2007 10:57 am ]
Post subject: 
Could be the winter gas, they oxygenate it usually so that it still burns clean, but mileage can suffer sometimes because there isn't as much energy in the same weight of gas, part of it is now an oxygenate instead of usable fuel.

Some vehicles it probably doesn't matter, but others it can hurt mileage, or so I have heard.
Author:  Renegade03 [ Mon Oct 29, 2007 11:15 am ]
Post subject:  Fuel mileage
Thanks JPaul. The change from winter to summer blend is not something I had considered. It makes sense. I am assuming that there are other parts of the country that do not make the switch or, have blends that vary, making variations in fuel economy less noticeable.
Author:  Jeepjeepster [ Mon Oct 29, 2007 11:15 am ]
Post subject: 
Mine usually drops off at least 1-2mpg in the winter. I figured it by hand the last two times and I got 20.5 for 200miles(temps around 85-90F) and 19.2 for 200 miles(temps around 50F). Im going to keep figuring it up as it gets cold to see what happens.
Author:  detroit_doc [ Mon Oct 29, 2007 2:45 pm ]
Post subject: 
Mine falls off pretty noticeably as well. I get 18 - 19 mpg in the summer and about 16 in the winter everything else being equal.

I've also noticed it seems to be a chrysler thing. I haven't noticed it in the GM/Pontiac, Honda or Subaru's I've owned.
Author:  Renegade03 [ Mon Oct 29, 2007 2:48 pm ]
Post subject:  Fuel mileage
I don't drive my wife's Caravan to know how much or little the fuel economy varies, but I don't remember this situation with my Pontiac, which I no longer drive in the winter.
Author:  Otto [ Mon Oct 29, 2007 3:05 pm ]
Post subject: 
i get about 16-17 in the summer and 14 in the winter. its uphill in almost every direction where i live so my numbers are going to be horrible no matter what. mileage drops off for me in the winter because in the mornings you typically need 4wd for the 5 fresh inches of snow on the ground before the plows get to work. i dont live in a flat place that doesnt get lots of snow so i cant really compare the mileage due to 4wd and hilly terrain. i could drive down to denver and get 23mpg in the middle of winter and have a near 200% increase in gas mileage just to show how remarkably different the driving can be.
Author:  Guest [ Mon Oct 29, 2007 8:47 pm ]
Post subject: 
colder air=denser=more air. more air seen by your MAF=more fuel injected into engine=fewer miles per gallon burned.

In theory.
Author:  Otto [ Mon Oct 29, 2007 8:52 pm ]
Post subject: 
ThunderbirdJunkie wrote:
colder air=denser=more air. more air seen by your MAF=more fuel injected into engine=fewer miles per gallon burned.

In theory.


Dont you mean fewer gallons per mile burned? i dont think you can burn miles, and maybe its just cause you worded it funny but you do mean what you ended up saying, that you get more miles to the gallon in colder weather?
Author:  Guest [ Mon Oct 29, 2007 8:58 pm ]
Post subject: 
no, that's actually exactly the opposite of what I mean.

"Fewer miles per gallon burned" means you go fewer miles per gallons of fuel that you burn.

Reading comprehension owns you! :lol:
Author:  myjeepwalks [ Mon Oct 29, 2007 10:25 pm ]
Post subject: 
If you wanna get technical the kj doesnt even have MAF sensor. It has a MAP sensor. :lol:


I'm back up to 14.7mpg from about 12.5 since i took off my roof basket and haven't been using the A/C. :roll:
Author:  Renegade03 [ Tue Oct 30, 2007 6:54 am ]
Post subject:  Cool weather mileage
All of the responses are great, but just to center this thread, I'm not talking about cold weather, I'm talking about the weather that we have been experienceing for the past four to six weeks in southeastern Michigan. Until this week, we were having daytime temps in the high fifties to the mid-seventies and night time temps down into the high forties. This is not cold weather. I understand that the MAP monitors the air temp and adjusts for that, but I also believe that at the tempertures mentioned above, the fuel adjustments shouldn't result in this type of fuel economy variation. I believe that the fuel blend probably has more to do with the change than does the vehicle's operating parameters. At first I thought that it was a problem with my vehicle or its state of tune, but after looking at my records, determined that this is just the way it is.

Also, I realize that my Liberty Renegade with off-road lights, roof basket, relatively square, flat frontal profile, protruding fenders, and running boards is not the most aerodynamic vehicle. I realize it everytime I am driving in any type of wind other than a tail wind (which for some reason happens very infrequently no matter where I am headed). With judicious use of the go-fast pedal, reading the traffic ahead, and timing lights, I have been able to get mileage as high as 22 m.p.g., althought that is highly uncommon. During the warmest times of the year, I regularly see 20 and often 21. In the winter, it drops down as low as 16, but generally is about 17 or 18.

I knew that this was going to be a mileage leader when I bought it; and fuel economy wasn't a reason for buying it, but with every other vehicle that I have ever owned, I have been able to regularly beat the EPA estimates. My 93 Grand Cherokee with the 4.0 liter was able to achieve 24 m.p.g. despite it's larger size. All of this wouldn't be of concern except that gas prices here are again over $3.00 and with the small fuel tank the Liberties have, I can only squeeze between 280 and 330 miles from a tank, meaning that I fill up one to two times a week.
Author:  ryno [ Tue Oct 30, 2007 11:19 am ]
Post subject: 
ThunderbirdJunkie wrote:
colder air=denser=more air. more air seen by your MAF=more fuel injected into engine=fewer miles per gallon burned.

In theory.


Otto wrote:
Dont you mean fewer gallons per mile burned? i dont think you can burn miles, and maybe its just cause you worded it funny but you do mean what you ended up saying, that you get more miles to the gallon in colder weather?


ThunderbirdJunkie wrote:
no, that's actually exactly the opposite of what I mean.

"Fewer miles per gallon burned" means you go fewer miles per gallons of fuel that you burn.

Reading comprehension owns you! :lol:


OWNED. :twisted:

myjeepwalks wrote:
If you wanna get technical the kj doesnt even have MAF sensor. It has a MAP sensor. :lol:


OWNED. :-)r
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