2001 WJ Horrible Gas Mileage 4.7 - JeepForum.com
 
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post #1 of 10 Old 11-20-2019, 10:27 PM Thread Starter
guitarfanatic21
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2001 WJ 
 
Join Date: May 2017
Posts: 24
2001 WJ Horrible Gas Mileage 4.7

Hello All,

I have 198,657 miles on it and it had an engine rebuild 8,100 miles ago because it dropped a valve and had warped heads. I have always had this issue with it and it says I average 12.4-12.8 MPG. I even calculated it and I am still getting roughly mid 12’s to 13’s. I have a pretty light foot too but she just drinks the gas like it’s water. When I first bought the car, it came with an aftermarket air intake. It is one of those dual twin short ram air intakes that sit over the engine. I feel like it just sucks in hot air maybe that is bad for gas mileage? I use the sprint drive obd monitor and it says the air intake temperature ranges from 140-180 degrees depending on the temperature outside (especially in the summer when it’s 100+). Should I get a cold air intake and relocate it to its original spot towards the front of the car for cooler air? Or is there anything else that might be causing issues?

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post #2 of 10 Old 11-20-2019, 10:29 PM Thread Starter
guitarfanatic21
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2001 WJ 
 
Join Date: May 2017
Posts: 24
The car is also stock it is not lifted or anything. I also have bad motor mounts I am going to replace in a week or two as the vibration is pretty terrible and the rubber is pretty much gone on those mounts.
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post #3 of 10 Old 11-20-2019, 10:37 PM Thread Starter
guitarfanatic21
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2001 WJ 
 
Join Date: May 2017
Posts: 24
Someone told me it should be running premium gas but since it is the non-HO version I thought I didn’t need to?
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post #4 of 10 Old 11-20-2019, 11:45 PM
Reech
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2001 WJ 
 
Join Date: Mar 2018
Location: Sheppard AFB
Posts: 70
Have any fault codes shown? Might have a bad sensor somewhere that is resulting in a fixed air/fuel map or something like that. I'm not super versed in that kind of stuff, just throwing out an idea. My 4.7 gets about 16-18 mpg on the hwy 13-14 in town with a 4in lift and a larger diameter MT tire. So if you are stock, you should definitely be getting better.
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post #5 of 10 Old 11-21-2019, 01:49 AM
funpig
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2002 WJ 
 
Join Date: Jul 2008
Location: Vancouver
Posts: 186
I usually average 15-16 mpg in the city on regular gas. I experienced lower mpg when my brake calipers seized up.

Past: '94 Laredo 4.0 242
Current: '02 Laredo 4.7 242
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post #6 of 10 Old 11-22-2019, 11:14 AM
MuloChico
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2006 WK 
 
Join Date: Nov 2015
Location: MODESTO
Posts: 141
Quote:
Originally Posted by funpig View Post
I usually average 15-16 mpg in the city on regular gas. I experienced lower mpg when my brake calipers seized up.
Ya, I was thinking checking for e-brakes not releasing, or brakes dragging. Air cleaner, tire pressure, etc. There is a lot more than just engine related things that can cause mpg issues.
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post #7 of 10 Old 11-22-2019, 12:47 PM
Oktavius
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2004 WJ 
 
Join Date: Apr 2018
Posts: 417
Quite a few people have commented on increased mpg after replacing the fuel filter. The fuel filter also contains the fuel pressure regulator. I noticed a few mpg increase after replacing mine.
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post #8 of 10 Old 11-22-2019, 04:31 PM
blueseasons
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2000 WJ 
 
Join Date: Oct 2015
Location: Santa Cruz
Posts: 586
If you are getting 12-13 "combined" MPG. You didnt say combined.. Then your right in the ballpark.
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post #9 of 10 Old 11-22-2019, 04:33 PM
blueseasons
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2000 WJ 
 
Join Date: Oct 2015
Location: Santa Cruz
Posts: 586
If you are getting 12-13 "combined" MPG and you didnt say combined. Then you are right in the ballpark.
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post #10 of 10 Old 11-23-2019, 07:05 AM
HarryH3
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2001 WJ 
 
Join Date: Jul 2015
Location: Planet Houston
Posts: 2,368
My non-HO 4.7 gets 13-14 mpg around town. On a recent hiway trip it got 18.5 MPG at an average speed of 75-80 MPH over 250 miles. Note that I don't pay any attention to the EVIC MPG reading. It's thrown off by my taller-than-stock tires. I use trip-odometer miles, multiplied by the GPS-confirmed speedo/odo error, and the amount of fuel that was pumped into the tank.
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