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  #1  
Old 03-20-2017, 09:56 AM
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5.8 mpg

I am just about out of ideas and my last resort is to take it to the dealership. I've been chasing down this problem for a while now and I've tried to take it to a few shops but they couldn't do anything. some said because there's no check engine light and no codes so there's nothing they can do. Others said it's normal for my 05 wk hemi, There is no way on earth that this car came out of the factory averaging 5-7 mpg. I'm stuck I've spent countless hours researching forums and posting, fuel trims, and looking at my scanner readings but nothing has worked.

2005 Jeep Grand Cherokee 5.7 Hemi
165k miles
5.6-6.5 mpg
110 miles of Range on full tank
Mostly city driven (NYC)

Here's what I've done so far:
>New thermostat & bled cooling system
-no change
>New pcv valve (found oil in air box so I changed it)
-no change mpg
>New Spark plugs
-went up to 8 mpg then dropped back down after two days
>Cleaned throttle body
No change
>New battery
>4 New o2 sensors
Went up to 11mpg and 250 range on full tank, dropped back down after a couple days
>Oil change
>Fixed exhaust leak
-no change, (fixed annoying sound)
>tried fuel cleaners
-no change
>Checked Map sensor readings through scanner, seams normal 8.9inHg at idle and my engine load at idle is at about 24%.

I don't want to keep throwing parts into it, my wallet isn't that deep. I put about 10 gallons in every 2-3 days. Only other problem at the moment is a slight vibration at idle but I think It's the harmonic balancer, intermittent squealing every few startups.
Besides that there's no performance issues and the jeep is an amazing machine and it's a really fun car to drive. But as you can see I'm just about out of options.
Any help?????

Thanks!



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  #2  
Old 03-20-2017, 01:18 PM
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Re: 5.8 mpg

how about changing the air filter element ??
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Old 03-20-2017, 02:00 PM
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Re: 5.8 mpg

Check compression?
Check injectors?
Check NADA/KBB for trade in value?
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Old 03-20-2017, 02:03 PM
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Re: 5.8 mpg

What about a brake dragging? Or parking brakes dragging? Do you feel any resistance when coasting or does it pull to one side when braking? Maybe check pads for even wear? Just throwing an idea out there, but if this has been going on for weeks or months I would think a dragging brake would have revealed itself by now with some kind of brake failure.
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Old 03-20-2017, 04:25 PM
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Re: 5.8 mpg

Quote:
Originally Posted by tom58 View Post
how about changing the air filter element ??

I forgot to mention I changed that too


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Old 03-20-2017, 06:08 PM
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Re: 5.8 mpg

Quote:
Originally Posted by SteelBlueWK View Post
What about a brake dragging? Or parking brakes dragging? Do you feel any resistance when coasting or does it pull to one side when braking? Maybe check pads for even wear? Just throwing an idea out there, but if this has been going on for weeks or months I would think a dragging brake would have revealed itself by now with some kind of brake failure.

I recently changed the brakes and rotors and always check up on them. My parking brake is not adjusted, its loose. Yeah, they would've failed by now.


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Old 03-20-2017, 06:14 PM
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Re: 5.8 mpg

Quote:
Originally Posted by xbombtek View Post
Check compression?
Check injectors?
Check NADA/KBB for trade in value?

I haven't done a compression test yet. As for the injectors I only got to check one of them and the ohms were at 14, I'll finish checking tomorrow. I think it's either the spark plug wires or the fuel injectors. As for selling it, I have a few friends who constantly offer to buy my car from me. But maybe next year when I get the srt


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Old 03-21-2017, 11:11 AM
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Re: 5.8 mpg

ImageUploadedByJeepGarage1490112654.576186.jpgImageUploadedByJeepGarage1490112681.318473.jpg


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Old 03-22-2017, 05:36 PM
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Re: 5.8 mpg

I'm now at 4.9 mpg with a range of 20 miles on a 1/4 of a tank.


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Old 03-22-2017, 06:47 PM
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Re: 5.8 mpg

Quote:
Originally Posted by Jcompres View Post
But maybe next year when I get the srt

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Then you'll get that kind of fuel economy normally because you won't be able to keep your foot out of it, LOL.....
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Old 03-24-2017, 08:37 AM
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Re: 5.8 mpg

If you haven't replaced the MAP sensor, I would try that. Even though readings at idle seem OK, may be off at other RPM's, and it is about a $25 part. Have you pulled any of the plugs to see if they are fouled ? If so, and it is running so rich, your catalytic converters will be clogged up by now from all the unburnt fuel.
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Old 03-26-2017, 07:44 PM
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Re: 5.8 mpg

Quote:
Originally Posted by dmsfun View Post
If you haven't replaced the MAP sensor, I would try that. Even though readings at idle seem OK, may be off at other RPM's, and it is about a $25 part. Have you pulled any of the plugs to see if they are fouled ? If so, and it is running so rich, your catalytic converters will be clogged up by now from all the unburnt fuel.

I actually just changed the map and coolant temp sensor and it brought it up to 9-10 mpg. Feel like there's still something missing, I'll try sea foam and a oil change since I'm coming up on 3k. I'll see if I can get a look at the cats.


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