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Unread 02-02-2013, 05:46 PM   #1
Aureliametal
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1998 ZJ 
 
Join Date: Nov 2009
Location: Prospect, Pa
Posts: 59
Estimated MPG on computer is weird...

Put 20 bucks of fuel in it. The estimated MPG says around 100 miles. Drive it 50 miles and it says 10 miles til empty. Turn it off and restart it and it goes back up to 50. Drive a few miles and it goes down to 20 miles. Drive a few more miles and it goes down to 10. Then it slowly starts to climb over the next few miles until I shut it down again. The Jeep has a broken overdrive so I was wondering if that screws it up. Otherwise, this is very strange. Any idea's? Thanks

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Unread 02-02-2013, 05:49 PM   #2
dnuccio
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1995 ZJ 
 
Join Date: Jul 2012
Location: Phoenix, AZ
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the overhead computer is not accurate at all. nothing is messing it up, thats just how they work. dont worry about it
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Unread 02-02-2013, 05:51 PM   #3
ratmonkey
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don't rely on that for anything. it takes the estimated amount of fuel left in the tank and multiplies it against the instant mpg you're getting.
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Unread 02-02-2013, 07:16 PM   #4
newfieZJ
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BTW , I recently went through a P0783 , and no OD . I tried different solenoids before finally replacing the trans(solenoids are in the trans I am using now) . After it was removed , I found out about the accumulator spring and it's issue with breaking and then no OD . Pulled the 5 screw cover and voila , 2 piece spring . I feel pretty confident I could have gotten OD with a new spring , 123 shifted great . I opted to switch because the oil had been let run really low , and some , well , a lot of debris in the pan when I opened it up . I didn't want to do the labor on the trans swap so I gave fixing it a shot , sure wish I would have tried the spring before swapping . I'd do a motor swap over the trans any day . After what I have experienced , I would certainly point the finger at a broken spring . Just thought I'd let you know . Could be a $10 fix , plus oil

Gas hand accuracy and DTE's aren't the greatest way to gauge what's left in the tank to take you that last 50 miles . I just filled up , drove 43 miles (70kms) since , and it's telling me 380 till empty (604kms). That's about 90-100 miles off what I will get , minimum . Never reset anything either . If I ran it down to using 21.5 gallons , that would make my 5.9 do 19.7mpgs . That would be better than the 14.2 I just pulled from the previous tank , same station used .
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Unread 02-03-2013, 12:13 AM   #5
Aureliametal
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Location: Prospect, Pa
Posts: 59
Cool, I am going to get the cascade master kit and it comes with that spring. The MPG est. works perfect on all my other grands. Just cant figure why this one is different.
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