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  #1  
Old 01-10-2012, 09:25 PM
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Thirsty 4.7

Hey guys! I have a 2000 Grand Cherokee with a 4.7. It is killing me with horrible gas mileage. I am only getting about 12 mpg. Any suggestions for how to improve it? What tire pressure should I run for the best gas mileage? Thanks.
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Old 01-10-2012, 10:09 PM
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Re: Thirsty 4.7

1) Your biggest determinate would be your driving habit and not to mention that Jeep's don't come from the factory as the most fuel efficient vehicle.

2) I would make sure your Oxygen sensors and fuel filters are in good shape.

3) Maybe make sure the engine is getting enough air from the air box by cleaning/replacing your air filter.

4) Replacing your spark plugs could help as well as cleaning or replacing your fuel injectors.

Here is a similar post to yours where fuel economy was discussed:

http://jeepgarage.org/showthread.php?t=27939
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Old 01-11-2012, 09:33 AM
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Re: Thirsty 4.7

I was having the same problem. I changed over to full synthetic oil, flushed and replaced all fluids, K&N CAI, E3 plugs, and upgraded the ground wires (not sure if that really made a difference) and I am now getting an average of 15.2 city. I also had to put my foot on a diet which i'm sure made a big difference too
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Old 01-11-2012, 09:42 AM
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Re: Thirsty 4.7

These guys are right...a LOT of it is about your right foot. I'd recommend the same stuff....
Tires inflated to recommeded spec on driver's door label
New fluids (stay up to date on diffs, transfer case, tranny)
Synthetic oil and a quality filter. I like Royal Purple and Mobil 1 with a K&N oil filter
Quality gasoline of the correct octane
Clean air filter, clean throttle body
General tune up (plugs, wires)
(A lot of people like using Seafoam to clean the engine internals...I've not used it yet)

Is your check engine light on?

How are you calculating your 12mpg? Are you actually recording mileage and doing the math or are you going based on what the onboard computer is telling you?
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Old 01-11-2012, 10:00 AM
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Re: Thirsty 4.7

I am getting 18.8 miles per gallon with my 2004 Overland with the HO power plant and 3.37 gears which came with the trailer package that is on my used ride. If i go on the highway and reset the calculator, we get 22 MPG. Like many have said, your habits might be the difference, although everything already covered might be a good thing to check and maintain.
How many miles are on your ride? As an engine wears, the milage usually drops which is an indication of lost power.
The O2 Sensors, a plugged catilac convertor, brake pads that are dragging. What type of drive does your Jeep have, Quadra Drive, Quadra Trac or any of the other types. maybe there is something wrong there! 4 Wheel all the time with some systems can drag the milage down. Does your exhaust smell which might mean yuo are running too rich. That wouls most likely set and error code and check engine soon light. maybe your is burned out. Does it light when you turn on the key? If it doesn't, the bulb may be burned out and not telling you that you have a code set.

Just some more ideas! Good Luck
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Old 01-11-2012, 10:09 AM
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Re: Thirsty 4.7

I have my suspicions with seafoam. Sometimes I think it's just a glorified smoke show. You will never see anything noticeably different after seafoaming. Some may beg to differ but I will stand true to my opinion.
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Old 01-11-2012, 03:01 PM
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Re: Thirsty 4.7

Quote:
Originally Posted by TJXJWJ View Post
(A lot of people like using Seafoam to clean the engine internals...I've not used it yet)
What do you like to use since you've never used seafoam?

Also, Does the K&N FIPK help any towards fuel economy or does it worsen it? I would still love to get one just for that raw sound alone lol.
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Old 01-11-2012, 03:57 PM
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Re: Thirsty 4.7

Quote:
Originally Posted by Reichminister Goebbels View Post
What do you like to use since you've never used seafoam?

Also, Does the K&N FIPK help any towards fuel economy or does it worsen it? I would still love to get one just for that raw sound alone lol.
The K&N FIPK and a good exhaust will help the engine breathe in and out better, resulting in better performance. Whether you put your foot down every chance you get or play nice is up to you lol. My wife thinks I'd get better MPG driving her car, haha
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Old 01-11-2012, 04:00 PM
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Re: Thirsty 4.7

Quote:
Originally Posted by 01grand View Post
The K&N FIPK and a good exhaust will help the engine breathe in and out better, resulting in better performance. Whether you put your foot down every chance you get or play nice is up to you lol.
Sounds good, Hey can you tell any improvements with your ceramic brake pads over the OEM kind? I'm guessing they're metallic or semi-metallic.
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Old 01-11-2012, 04:27 PM
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Re: Thirsty 4.7

I figure the mileage by hand. I have 240,000 on the original everything. How do I change the fuel filter? And what kind of transmission service and how to do it? Thanks.
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Old 01-11-2012, 05:05 PM
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Re: Thirsty 4.7

Quote:
Originally Posted by janisonh View Post
I figure the mileage by hand. I have 240,000 on the original everything. How do I change the fuel filter? And what kind of transmission service and how to do it? Thanks.
Here's a great explanation:

http://wjjeeps.com/fuel_filter.htm
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Old 01-11-2012, 05:06 PM
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Re: Thirsty 4.7

Quote:
Originally Posted by Reichminister Goebbels View Post
Sounds good, Hey can you tell any improvements with your ceramic brake pads over the OEM kind? I'm guessing they're metallic or semi-metallic.
I'm honestly not sure if they perform better or worse, braking power seemed about the same to me when I changed them from the originals. Well, what was on there when I bought it with 111,000 miles on it lol. I like them for the less visible dusting on the wheels, and they are quiet. On my old ZJ I drove it for 3 years, didn't hear a squeak from the brakes until the pads were totally gone, it was metal rubbing on metal.
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