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-   -   BS Gas Mileage (http://www.jeepgarage.org/f181/bs-gas-mileage-33601.html)

2005 WK 01-06-2012 07:08 AM

BS Gas Mileage
 
I have been getting 10-11 mpg in my 4.7. A full tank will take me about 200 miles or less. I feel like something is not right here, I know I got a v8 and its not good on gas but 200 miles per tank? Is there anything i can do to boost my mpg up to at least 14-15. Tune up is recent along with all fluid maintenance. Tires are always properly inflated and I am not an aggressive driver. Any input would be great.

JonJon 01-06-2012 08:53 AM

My fuel economy recently took the same dive. I get about 220 miles per tank and that's with 80% highway driving. The transmission seems to be holding onto the gears for far to long. So I brought it into the dealership to have them look at the transmission because I have an aftermarket warranty. I'll let you know what my problem is, if you have similar issues.


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Blueflame1979 01-06-2012 09:38 AM

Re: BS Gas Mileage
 
Quote:

Originally Posted by JonJon (Post 546740)
My fuel economy recently took the same dive. I get about 220 miles per tank and that's with 80% highway driving. The transmission seems to be holding onto the gears for far to long. So I brought it into the dealership to have them look at the transmission because I have an aftermarket warranty. I'll let you know what my problem is, if you have similar issues.


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Yes please keep us Posted, My transmission also seems as if it takes longer to shift maybe dragging somewhat and I feel as if the pedal is not as reactive as it should be. I just recent changed to valvoline atf+4 synthetic to see if that made a difference, but it hasn't. As you can see I also have a 4.7 V8. My Gas Mileage gets as low as 6.8 in the City this winter with the Heater on, and 8.0 in the Highway. I thought it was bad, when I first got 7 months ago around springtime which was 8.9 in the city and about 10-11 in the highway. I got a tune- up from a local mechanic that services every vehicle the same way with the same fluids and plugs and everything. After doing much research I discovered Jeeps take specific things in order to perform at its best. I'm just rolling with the punches and will start working on my own Jeep when the weather gets warmer and I have extra money.

Chaoul1 01-06-2012 10:06 AM

Re: BS Gas Mileage
 
Make sure you guys are using the correct spark plugs. ALso check your air filter too!

NHWK05 01-06-2012 10:15 AM

Re: BS Gas Mileage
 
Im feeling the same pain with my 4.7L. Ive got an 05 with 105k miles on it and since i bought it my MPGs have gone from 18 plus highway to barely 15 mpg highway. Im going to do new spark plugs (oem or champion) and im getting rid of my performance exhaust and Ported TB to see if putting it back to how it was when i bought it will help.

Is there anything else that can be done for this engine as far as tune up goes?

Does anyone recommend a good fuel injection cleaner?

I am averaging 11 mpgs according to the EVIC.

I knew buying a 4.7 it was going to be a gas hog compared to the hemi but i could not afford the hemi model i wanted. Though i never expected this bad mpgs.

Redpit 01-06-2012 10:37 AM

Re: BS Gas Mileage
 
Winter blend gas has hurt my mpg. Probably brought mine down about 1mpg. Your guys seemed to have dropped more severe (so this alone is prolly not your problem), but I figured I'd throw it out there as one of the possible contributing factors.

JonJon 01-06-2012 02:49 PM

So I just got back from the dealership, and they say it could be my fan clutch. I saw that it was spinning freely and making a gravely sound when I replaced my water pump, just hadn't gotten around to replacing it. They had it hooked up to the computer for about and hour and took it on a test drive with the service manager and computer for another 15-20 min. They said everything is running as it should. Torque converter locking up when it should, transmission shifting at the designated shift points, and line pressure where it should be.

I came home and replaced the clutch, and man is it quiet now. I didn't even realize how loud it was. The engine definitely runs a lot smoother and doesn't need to rev up so high. Seems to have fixed the way it was running. I'll let you know how it works out with the gas mileage part when I put some more miles on it.

I just did a full service about 10,000 mi ago (tranny service, diffs changed out, transfer case changed out, and champion spark plugs.) So I think I should be good and it wouldn't explain why it just started. Hopefully the clutch solves my problem. I'll let you guys know.


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Blueflame1979 01-06-2012 02:50 PM

Re: BS Gas Mileage
 
Quote:

Originally Posted by Redpit (Post 546797)
Winter blend gas has hurt my mpg. Probably brought mine down about 1mpg. Your guys seemed to have dropped more severe (so this alone is prolly not your problem), but I figured I'd throw it out there as one of the possible contributing factors.

I think that's part of the problem, I think my other part of the problem is computer related or not having the right parts in my Jeep to get it to the best performance, I can't wait till it warms up so I could start working on Her.

NHWK05 01-06-2012 02:52 PM

Re: BS Gas Mileage
 
It would be awesome if that's the problem. Easy fix to get better mpgs. I'm curious to hear what kind of changes you see over the next few days.

Blueflame1979 01-06-2012 03:51 PM

Re: BS Gas Mileage
 
I also think that my gas cap has something to do with it, it seems to click and keep running when tightening it. It hasn't thrown any codes for it a mechanic at one time was surprised that it didn't. Maybe gas cud be evaporating from there its like a 35 dollar part so I don't lose anything replacing it when I get the chance.

FlyinRyan 01-06-2012 04:07 PM

Re: BS Gas Mileage
 
Bad catalytic converter, air filter....

jeepgcoman 01-06-2012 06:38 PM

Re: BS Gas Mileage
 
As said, winter fuel, cooler temps. causing longer warmups and delayed upshifts can cause some of these issues. If you have more than 100K on it, consider changing the O2 sensors and perhaps the MAP sensor. O2's are like spark plugs and become lazy and/or inaccurate with age. You may not get a light either. When O2's fail, they tend to send "richen the mixture" signals to the PCM. Check this thread out:

http://www.jeepgarage.org/f183/oxygen-sensors-and-their-role-in-engine-management-a-primer-20300.html


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