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Unread 03-14-2013, 10:10 PM   #1
Jakes93yj
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1993 YJ Wrangler 
 
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Gas mileage so low?

I know my 93s yj 4.0 was going to be bad on gas for around town, but I wasn't expecting 10-12mpg on a 20 gallon tank. Is there something that could cause this? And how could a test the part if its bad or not? Also I'm goin to the beach in 2 weeks and will report back with the gas mileage after a lovely 200 mile drive. Thanks for reading.

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Unread 03-14-2013, 10:20 PM   #2
amiller
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Seems like I'm getting the same mileage. The jeep wrangler has a drag coefficient worse than that of a brick. I have a YJ and a TJ. Neither one did I buy for economy. Just for my driving fun.
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Unread 03-14-2013, 10:28 PM   #3
Jakes93yj
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Re: Gas mileage so low?

Ok. I thought I was the only one getting crap for gas, its expensive for these things to be a DD. Is yours lifted or anything? Mines completely stock(for now). I plan on going with a 4" RC lift and 33x12.50 bfg km2's or nitto mud terrains. So there goes more gas.

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Unread 03-15-2013, 09:11 AM   #4
pete1991YJ
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Tune-up time, in a big way. You should be able to get 17-18 MPG's with a mostly stock 4.0. I'm getting ~20 with the 4-banger. The O2 sensor is the #1 thing that determines your fuel mileage. Also check if the exhaust manifold is tightly bolted onto the head -- leaks here can fool the O2 sensor. Check for vacuum leaks by spraying some carbcleaner around the ends of all the vacuum hoses. Especially the fuel pressure regulator. Make sure the return lines aren't pinched at the tank. Check the air filter.
All these things affect the MPG's.
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Unread 03-15-2013, 09:32 AM   #5
RowJ
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19-20 w/ a 4 cyl....maybe. I have no experience with them.
But 17-18 mph on a 4.0L is VERY rare...... and if honest test, with no tail wind and not going downhill all the way ....
I suspect never!

My best ever, with a new engine and across level west Texas for 150 miles, was 15.1 mpg. And that was at 55 mph.


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Unread 03-15-2013, 09:45 AM   #6
wanabejeeper
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I'm getting about 10 on a recently rebuilt 4.2/ Weber, nuttered, Team Roush and MSD 6 ignition. I'm using a fuel/air gauge so I'm pretty sure my mix is correct but I still have to take it to inspection to be sure. I'm leaning more towards my 3.07 gears and 31" tires as the problem. I have a 4 wire A/F gauge I'm going to install in a few weeks. I'm also going to confirm my engine RPM's and install a tach that will work with my ignition. I'm planning a frame off next year and if I feel the gears are the problem I'll do either an 8.8 or a D44 rear with 3.55's and regear my D30. Having said that I never expected my mileage to be much better than 15 anyway.
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Unread 03-15-2013, 10:05 AM   #7
tdewit
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My wife's '95 4 banger, between 18 and 20 MPG, depends on the day. Dead stock.
My '91 4.0, between 14 and 15 MPG. 31's with a 1" BL
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Unread 03-15-2013, 04:05 PM   #8
ryanderson
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I went from 10 to 13 mpg just by changing oil and diff. oil
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Unread 03-15-2013, 06:12 PM   #9
Chrisnvegas
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I recently filled the tank (20 gal) drove 110 miles. Have 3/4 left. although it seems to use the bottom half faster than the top half.

I have checked my MPG in the past. As bad as 12 at high highway speeds (75+) or as high as 17 or 18 (under 65)

I have an automatic so at 70 I'm pushing almost three grand.
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Unread 03-15-2013, 06:41 PM   #10
blown50
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17 -23 mpg 4.7 stroker 3:08 gears 5 speed 30 inch radial tires, hard top with air and it will hit triple digit mph
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Unread 03-15-2013, 07:30 PM   #11
Chrisnvegas
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Quote:
Originally Posted by blown50 View Post
17 -23 mpg 4.7 stroker 3:08 gears 5 speed 30 inch radial tires, hard top with air and it will hit triple digit mph
We don't want to hear about it.
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Unread 03-15-2013, 08:10 PM   #12
pete1991YJ
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Seriously tho, I think the OP's gas mileage is too low even for a big 6-cylinder and a lead foot. There are other guys on here getting much better than that with the exact same setup.
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Unread 03-15-2013, 09:34 PM   #13
Jakes93yj
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Re: Gas mileage so low?

Quote:
Originally Posted by pete1991YJ View Post
Seriously tho, I think the OP's gas mileage is too low even for a big 6-cylinder and a lead foot. There are other guys on here getting much better than that with the exact same setup.
Seriously, its not lifted(yet) it has stock motor, stock tow package, 30 in radial bfg at's, its a hard top, everything is stock
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Unread 03-15-2013, 10:37 PM   #14
pete1991YJ
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Quote:
Originally Posted by Jakes93yj View Post
Seriously, its not lifted(yet) it has stock motor, stock tow package, 30 in radial bfg at's, its a hard top, everything is stock
That's exactly what I mean, you should be getting at least 15 MPG's if not more.
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Unread 03-15-2013, 11:19 PM   #15
yellow2kgt
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Do you have an automatic or 5 speed? That sounds about average for the 3 speed auto. No overdrive really hurts the mpg. The best I ever got from my auto YJ was 14 mpg when stock
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