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Unread 02-11-2014, 12:52 PM   #76
jcgf1
Registered User
1998 XJ Cherokee 
 
Join Date: Feb 2014
Location: Montreal, Qc
Posts: 3
Gas milage

Hi

hello my jeep is killing me with gas consumtion 260 kn per tank... new 02 sensor and injector rail was liking...till same problem.. but when i touch the injectors, rail.. etc... then i got 350 km... Please help!

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Unread 03-11-2014, 11:20 PM   #77
wj47ho2004
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2004 WJ 
 
Join Date: Mar 2014
Location: pittsburgh, pa
Posts: 37
My mostly stock fipk 4.7ho gets 13-14 mixed and 18-19 hwy. I run 91-93 octane. I installed plastic to block the about 3/4 the rad on this and my truck in the winter. The quicker it gets there and the warmer the engine runs, the better the mpg.
My old 94zj 5.2 got 1-2 mpg higher mpg after I did a electric ford super coupe fan mod. Much faster warm up and less stress on the waterpump.
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Unread 10-22-2014, 09:51 AM   #78
myjeep1
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2008 JK Wrangler 
 
Join Date: Oct 2014
Location: fort myers, fl
Posts: 1
very poor gas mileage

I have a 2008 wrangler , 3.8 , manual transmission with only 30,000 miles . I am getting approx 12 miles/ gal. engine light is on so the dealer ran a diagnostic to detemine issue. they told me i needed front and back 02 sensors replaced , which i did. 30 miles later engine light is back on and no improvement in gas mileage.
any suggestions ?
Thanks
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Unread 11-21-2014, 07:26 PM   #79
potterJeep
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Join Date: Nov 2014
Posts: 2
9mpg

Help just dropped from 12.0 to 9.3 Jeep Grand Cherokee 5.7
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Unread 11-21-2014, 07:29 PM   #80
potterJeep
Registered User
 
Join Date: Nov 2014
Posts: 2
I am only getting 9.3 it dropped today from 12.0 to 9.3 any ideas never been below 10.0 2010 Jeep Grand Cherokee 5.7 liter
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Unread 02-24-2015, 04:27 PM   #81
Charley3
Web Wheeler
1999 XJ Cherokee 
 
Join Date: Mar 2013
Posts: 4,345
Synthetic oils are less affected by temperature. So in cold weather that helps gas mileage some.
There's several things that I've done that improved my 4L gas mileage year round, city and highway.

The main items are 205F Stant thermostat, Kolak ignition kit with plugs at 0.045 gap, modern 4 injectors, high flow intake, 2.25" cat back, appropriate weight synthetic oils in everything, slightly positive rake, no winch or roof rack, and a few other things.

In cold weather a partial grill cover would also help, but I don't have one yet.

I made a thread about it. My 99 XJ currently gets 25 mpg at 60 mph (in coastal air) even with 30" tires, low lift, and 200 lbs skidplates.
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Unread 02-24-2015, 04:44 PM   #82
Charley3
Web Wheeler
1999 XJ Cherokee 
 
Join Date: Mar 2013
Posts: 4,345
P. S. - The Kolak ignition and my 0.045 gap is giving a longer and hotter spark.

The 205F thermostat helps engine get to at least 205F no matter how cold the weather, and if weather is above 25F my Jeep runs 210F (perfect).

The modern 4 hole injectors spray a fine mist of fuel instead of a single stream.

So from those things my combustion is hotter and more complete. So more efficient. I also have easier cold starts, runs smoother, and more torque and power.

I do not have any predetonation problems. I use 89 octane gas, though it might not be necessary. It runs smoother on 89, has slightly more performance, and I suspect 89 helps my gas mileage.
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Unread 03-12-2015, 12:56 AM   #83
Charley3
Web Wheeler
1999 XJ Cherokee 
 
Join Date: Mar 2013
Posts: 4,345
Here is a thread that lists affordable, cost effective mods that have improved my 99 XJ's 4L gas mileage.

http://www.jeepforum.com/forum/#/for...topics/1551782
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Unread 03-17-2015, 01:46 AM   #84
MyLiberty04
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Join Date: Mar 2015
Location: Atlanta, Georgia
Posts: 2
My Engine light is on & some other stuff Please Help... Just bought my first Jeep, 2004 Liberty and I love it but the next day the engine light comes on, I take it back tell them what happened he plugs a machine in clears it and says sometimes when they fix something the computer doesn't recognize it right way but also my windows were flogging up the defrost wouldn't work, and when I rode over a speed bump my oil light came on and then went off. I went back again because I just paid everything I had for some reliable transportation and I need some answers they say it's a heater coil and to bring it back tomorrow on Tuesday and they will fix it. But, I want to be safe than sorry so if anyone can... please help me I plan on stopping by Auto Zone before I take it back and let them plug in their machine so I'll know for myself and get codes on my own. Please help. I know nothing about Jeeps but I love mine.
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faq , gas mileage , improve mpg , miles per gallon , mpg , poor gas mileage

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