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Unread 05-02-2013, 11:10 AM   #1
veiri86
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Wj Unexpected MPG for JGC WJ 01 4.7

Hi JF,

I had an MPG of 15 at highway, so I thought I wanna be like the others to reach around 20 MPG at highway and save some fuel, so I changed the spark plugs with new ones from Champion; Champion copper plugs, the car started to response better but the MPG was not affected at all and stayed at around 15 MPG highway

Then one week later, I though of changing the TPS as I was thinking that it is not performing like before, but it was still ok.

So I changed the TPS with new one from Crown, then replaced the fuel filter, both were replaced at the same time.

Then I went on drive, the car responses better, and shifts smoother, but I was shocked by the new MPG, it was 5 MPG. So I though to disconnect the battery and give the ECU chance to learn the new TPS, so I reconnected the battery again, but the MPG still around 5 MPG.

The car now responses very well and shifts smooth, but the MPG makes me crazy,

Any idea guys?

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Unread 05-02-2013, 11:17 AM   #2
TeeJay4490
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is it actually 5mpg or does it say that on the EVIC
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Unread 05-02-2013, 11:18 AM   #3
brianestep
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Is that 5mpg calculated by the EVIC, or calculated by hand? I'd do the math on it first. The EVICs are notoriously incorrect, especially if you reset the battery. It may take a few starts for the computer to reset itself and adjust to the new parts.
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Unread 05-02-2013, 11:19 AM   #4
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Quote:
Originally Posted by TeeJay4490 View Post
is it actually 5mpg or does it say that on the EVIC
Ha! Winner
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Unread 05-02-2013, 11:47 AM   #5
veiri86
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Quote:
Originally Posted by TeeJay4490 View Post
is it actually 5mpg or does it say that on the EVIC
Quote:
Originally Posted by brianestep View Post
Is that 5mpg calculated by the EVIC, or calculated by hand? I'd do the math on it first. The EVICs are notoriously incorrect, especially if you reset the battery. It may take a few starts for the computer to reset itself and adjust to the new parts.
Quote:
Originally Posted by brianestep View Post
Ha! Winner
It is by the EVIC, I will calculate it by hand tomorrow manually and update you
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Unread 05-02-2013, 12:22 PM   #6
TeeJay4490
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10-4 man. hopefully the evics messing up
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1999 Grand Laredo 4x4: [SIZE="2"]Whats left of a front bumper - JK Saharas' with 33's - 4 in. Rough Country lift - HID conversion - Double cardon conversion - TJ gas cap mod - Recovery points added - Painted cladding and grill - Skid plates - All moog suspension- Roof Rack -CB radio - Cut and trimmed fenders[/SIZE]

[url]http://www.jeepforum.com/forum/f197/tjswj-build-thread-1438516/[/url]

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Unread 05-02-2013, 01:24 PM   #7
VinceWj
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Doesnt the 4.7 suppose tto use some fancy spark plug? I thought the copper one were only good for the 4/0 and the V8 needed the platinum one
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Unread 05-02-2013, 01:28 PM   #8
brianestep
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Quote:
Originally Posted by VinceWj View Post
Doesnt the 4.7 suppose tto use some fancy spark plug? I thought the copper one were only good for the 4/0 and the V8 needed the platinum one
Only for H.O.
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Unread 05-02-2013, 01:32 PM   #9
VinceWj
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well..... Is that one an H.O.? lol
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Unread 05-02-2013, 02:13 PM   #10
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Do make sure to reset the EVIC by pressing the reset button when the Avg fuel mileage is displayed.

I've not reset mine since I did spark plugs but when I did, there was joy in the numbers.

I'll probably reset it again in about 10K miles just to see if I can change skinny pedal habits over the following 10K miles and do any better.
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Unread 05-02-2013, 03:01 PM   #11
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The EVIC also takes a while to gain an average not just 5 miles... it takes about 100 to start to get an average... instant is just how heavy of load and foot you have.. doesn't mean anything unless the instant says 5... let you foot rest a little...

I have reset mine several times over the past month with disconnect negative for 15min... it takes about day or so for averages to work up.... I am at 14 city with I6... just got my new fuel filter today... now waiting for rain to stop for little bit....
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Unread 05-02-2013, 03:41 PM   #12
ezflip
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Dump the crown TPS and get one from MOPAR. These things are very very picky about their sensors. Anything electronic, use nothing but Mopar.
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Unread 05-02-2013, 06:05 PM   #13
WJChris
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also. what temperature is your gauge reading? Jeeps run rich when not up to 210.
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Unread 05-02-2013, 06:17 PM   #14
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I also have an 01 v8 limited. I get about 21mpg combined. Usually around 18-19 city and 22-23 highway. I am a moderate driver, sometimes I am conservative with the gas, other times I drive the suv hard. That v8 is fun to drive and hard to resist the throttle

Is your jeep utilizing overdrive?
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Unread 05-02-2013, 06:18 PM   #15
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I should also mention that I am using Bosch o2 sensors.
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