2005 jeep grand cherokee limited mpg

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  #1  
Old 03-11-15, 08:24 PM
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Arrow 2005 jeep grand cherokee limited mpg

Hey yall, I just recently bought a used 2005 jeep grand cherokee limited with a V8 and 4.7 liter engine. This jeep is stock with no lifts and regular tires. On the drive home from the dealership I was getting pretty good gas mileage (like upwards of 15 according to the mpg calculator on the display, which i don't know if i can trust) As far as i know nothing changed from that time an now and for some reason i am now getting 8 mpg based upon my manual calculations. I've been researching what could be causing this and so far I've replaced air filter, spark plugs, thermostat (because it went out) Are there any thoughts as to why I'm getting this kind of mileage? From my research this seems drastically low. Any thoughts would be greatly appreciated! Thanks
 
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Old 03-12-15, 04:02 AM
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Welcome to the forums!

I don't trust the mpg readout on the dash. I have one on my wrangler and it always shows 1-3 mpg better than what I actually get 4x4s never get great mileage but a V8 should get better than that!

Are you sure it's not stuck in 4 wheel drive? how does it run otherwise? what does the inside of the tailpipe look like?
 
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Old 03-12-15, 04:54 AM
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My first thought was a 4x4 issue, too (if it's a 4x4). Second thought would be O2 sensor, that's usually the culprit when the mpg on my wrecker goes south [it's usual mpg is about 8 1/4]. Would think you would have a check engine light, though. Might want to get codes checked, but to get a real-time look at how things are operating it will need a full-function scanner.
 
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Old 03-12-15, 02:09 PM
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It is a 4x4 and that's something that I forgot to mention. When I got It the dealer made me aware that it needed a new transfer case motor and that 4 lo didn't work. I researched it a bit and found that there is an issue with the fuse box circuit board. I pulled out FDCM ediff and drove around a bit and then put it back in and turned off the engine and the 4 lo worked after that. But I think the motor may still need repairing because upon initial startup it's as if it is in 4 lo and is pretty rough and then after 10 seconds of driving it seems to kick out of it. Maybe 4 lo is partially enabled while i'm driving, but that doesn't make sense if im going 70 down the freeway. I ended up just pulling the FDCM ediff fuse out all together to cut off power to the transfer case motor so i don't have that issue on startup anymore.

From what i understand there are lots of issues with the 4x4 with this model and year.

I also forgot to mention that the ABS light came on and got the codes read (by my Dad, he's a diesel mechanic) Left rear ABS sensor and Left Front ABS Sensor have issues according to the readout. I haven't replaced those yet, seeing as i just bought a 'new' used car. I doubt that an issue with ABS could cause any issues in gas mileage though.

marksr - I'll take a look at the tailpipe when I get out of school.
 
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Old 03-13-15, 04:28 AM
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Is yours the 4x4 version with 4H-N-4L selector or 2H-4H-N-4L?
 
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Old 03-13-15, 05:10 AM
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Is it quadratrac? Mine is a 2000 so it may be little different. Since you just bought it, how many tanks of gas have you run through it to obtain your mpg data? The overhead or dash indicator isn't all that accurate, but fun to watch as it changes. I get 16+ around town and 20 on the road with the v8.
 
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Old 03-13-15, 06:23 AM
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Daughter recently traded up to a newer Corolla and it has 2 functions for MPG; one for average and one for real-time. Took me a bit to figure it out. Interesting to watch it go to <10 mpg when you step on the gas.
 
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Old 03-13-15, 11:44 AM
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Yeah, the Cherokee has that, too. Nice when you are coasting down a hill at 63 mpg, though
 
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Old 03-13-15, 02:35 PM
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Yeah it is a quadatrac with the 4hi - N - 4lo. It's basically always in 4hi, it's essentially an all wheel drive vehicle.

And I've been through about 2 tanks of gas since I bought it on Feb 28th 2015.

I want to look in to the 02 sensor. But aren't there multiple 02 sensors?
 
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Old 03-13-15, 04:00 PM
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I was doing some research, like you, since I have a Limited, also. Was your car involved in the N23 recall by Chrysler? Supposedly it only involved 2005-2010 vehicles. If you read the responses you will see a link to a supplier of the modules. A replacement may be needed. Problem with Jeep Grand Cherokee transfer case - Technical Tips and Tricks - Escapees Discussion Forum

This is the recall letter sent by Jeep: http://www.jeep.com/webselfservice/pdf/N23.pdf
 
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Old 03-13-15, 05:19 PM
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You know, that's something I recently read. If you buy a used vehicle or have moved quite a bit recently, always call the 1-800 number or stop by a local dealer to check on recalls that may have been missed. Used off that manufacturers dealers lot is not as big a problem, but I think CarMax is in a lawsuit for not checking on recalls for the cars they sell.
 
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Old 03-14-15, 09:15 AM
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Yeah, had to take her car to Jeep Dealership for a valve rocker replacement, and noted on the invoice they ran a check for all recalls, including the one for the gas tank protection, which entails installing a frame mounted hitch assembly, go figure. We already had one, but appreciated them checking it for us.
 
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Old 03-15-15, 07:27 PM
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So... Recent update. This past Saturday My Dad brought home his scanner and we were checking things out on the Jeep. It's obvious that the Left Rear ABS Sensor needed to be replaced because on the real time scanner, the Left Rear wasn't reading any distance traveled. So we replaced the ABS Sensor. We also through the FDCM ediff back in and EVERYTHING WORKED PROPERLY! I can now go in to 4lo with ease and there are no hiccups anywhere. The only thing that we can figure is that the quadratic system pulls from the information that the ABS puts out and because the left rear sensor wasn't reading anything the 4 wheel drive system wasn't working properly.

Another thing.... Since i replaced the sensor my gas mileage has gone up! (according to the EVIC system) I'm going to manually track it though, just to make sure. But according to the MPG reading i went from 7.9 city to about 14 city. I'M SO HAPPY!
 
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