Teribble mpgs - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ General Discussion Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 02-16-2012, 12:41 PM   #1
Jeeper
 
Join Date: Sep 2011
Posts: 21
Teribble mpgs

Hey guys, I have a 1998 jeep wrangler Sahara with 73,000 miles. I have only been getting about 9-11 miles per gallon, and I drive pretty good as far as hammering the throttle. It's an automatic and sometimes when shifting from 2 to 3 it will take up to 3500 Rpms to shift, or if I let of it will shift then I can get back in it. Any suggestions on why I'm getting such bad gas or bad shifting?

jwrangler98sahara is offline   Quote
Old 02-16-2012, 12:46 PM   #2
Jeeper
 
JakesTJ's Avatar
 
Join Date: Jan 2012
Location: Holly, MI
Posts: 49
Tell us more...Any modifications (lifted, bigger tires, etc.)

JakesTJ is offline   Quote
Old 02-16-2012, 12:53 PM   #3
Jeeper
 
Join Date: Sep 2011
Posts: 21
I have a 4 inch lift on 33s. No other mods that would effect if
jwrangler98sahara is offline   Quote
Old 02-16-2012, 12:55 PM   #4
Jeeper
 
Owen_TJ's Avatar
 
Join Date: Sep 2010
Location: Denver, CO
Posts: 4,356
I looked at your previous posts and it looks like you're running about a 4" lift and 33's (edit: you beat me to it)

you're not too far off from normal mileage with stock gearing and an automatic with the 33's...not sure which gearing you're running but my guess would be 3.07's or 3.73's (<- most likely)

i would have guessed you more in the 13-14 range...if you havent already (or recently), do a tuneup for it with some new plugs, wires, dist, new filter, and oil change
Owen_TJ is offline   Quote
Old 02-16-2012, 12:57 PM   #5
Jeeper
 
Join Date: Sep 2011
Posts: 21
I just did an oil change and new filter. I think I'm going to try new plugs and a fuel filter.
jwrangler98sahara is offline   Quote
Old 02-16-2012, 12:57 PM   #6
Jeeper
 
JakesTJ's Avatar
 
Join Date: Jan 2012
Location: Holly, MI
Posts: 49
Quote:
Originally Posted by jwrangler98sahara View Post
I have a 4 inch lift on 33s. No other mods that would effect if
Quote:
Originally Posted by Owen_TJ View Post
I looked at your previous posts and it looks like you're running about a 4" lift and 33's

you're not too far off from normal mileage with stock gearing and an automatic with the 33's...

i would have guessed you more in the 13-14 range...if you havent already (or recently) do a tuneup for it with some new plugs, wires, dist, new filter, and oil change
Also if you havent compensated the speedo gear for your bigger tires you will actually be seeing less mpg than you are actually getting...
JakesTJ is offline   Quote
Old 02-16-2012, 12:59 PM   #7
Jeeper
 
SirGeorgeKillian's Avatar
 
Join Date: Mar 2011
Posts: 1,282
Images: 2
If you are running stock gears, that is as good as it gets for you with that sized tire....
__________________
Check out my videos:
http://www.youtube.com/user/TrailRatedCustoms/videos
SirGeorgeKillian is offline   Quote
Old 02-16-2012, 01:00 PM   #8
Jeeper
 
Join Date: Sep 2011
Posts: 21
That is true. Do you know how to compensate that? And is the transmission taking a while to shift something odd?
jwrangler98sahara is offline   Quote
Old 02-16-2012, 01:05 PM   #9
Newb
 
Join Date: Feb 2012
Posts: 9
98 grand cherokee's have a speed sensor int he tranny that, when it goes bad, will cause the issue of high RPM's needed to shift. I would think you would be getting a check engine light if it was bad but you never know.
MiltsJeep is offline   Quote
Old 02-16-2012, 01:13 PM   #10
Jeeper
 
JakesTJ's Avatar
 
Join Date: Jan 2012
Location: Holly, MI
Posts: 49
Quote:
Originally Posted by jwrangler98sahara View Post
That is true. Do you know how to compensate that? And is the transmission taking a while to shift something odd?
Here Jeep Parts, Jeep Accessories & Jeep Soft Tops From The Jeep Parts Experts - Quadratec your high rpm's might just be the motor pushing harder do to the tires, gearing and lift
JakesTJ is offline   Quote
Old 02-16-2012, 01:14 PM   #11
Jeeper
 
Atthehop's Avatar
 
Join Date: Jul 2008
Location: NW, NJ
Posts: 3,957
Quote:
Originally Posted by jwrangler98sahara View Post
Hey guys, I have a 1998 jeep wrangler Sahara with 73,000 miles. I have only been getting about 9-11 miles per gallon, and I drive pretty good as far as hammering the throttle. It's an automatic and sometimes when shifting from 2 to 3 it will take up to 3500 Rpms to shift, or if I let of it will shift then I can get back in it. Any suggestions on why I'm getting such bad gas or bad shifting?
Are you basing your MPG on actual miles driven and actual gallons pumped. It seems some are calculating it on fuel gauge readings.
__________________
Retired my 94 YJ 4cyl 5spd @ 200K
Now in a 04 TJ 4cyl 5spd CV @120K+
Both as a commuter vehicle in NW, NJ
April 2012.downsized and now a 99er.
Atthehop is online now   Quote
Old 02-16-2012, 01:28 PM   #12
Jeeper
 
Join Date: Sep 2011
Posts: 21
I just divided my miles driven by gallons pumped (172miles/17.1 gallons)
jwrangler98sahara is offline   Quote
Old 02-16-2012, 01:34 PM   #13
Jeeper
 
SirGeorgeKillian's Avatar
 
Join Date: Mar 2011
Posts: 1,282
Images: 2
Quote:
Originally Posted by jwrangler98sahara
That is true. Do you know how to compensate that? And is the transmission taking a while to shift something odd?
Regear front and rear axles. Is your spedo correct for the size tires you are running? That could also make your calculations off.
__________________
Check out my videos:
http://www.youtube.com/user/TrailRatedCustoms/videos
SirGeorgeKillian is offline   Quote
Old 02-16-2012, 01:34 PM   #14
Jeeper
 
JakesTJ's Avatar
 
Join Date: Jan 2012
Location: Holly, MI
Posts: 49
Quote:
Originally Posted by jwrangler98sahara View Post
I just divided my miles driven by gallons pumped (172miles/17.1 gallons)
^thats what im saying George
Yea you need a new speedometer gear for 33" tires...without it it makes your odometer read less. You say 172 miles, could be closer to 250 more or less??
JakesTJ is offline   Quote
Old 02-16-2012, 01:34 PM   #15
Jeeper
 
Owen_TJ's Avatar
 
Join Date: Sep 2010
Location: Denver, CO
Posts: 4,356
Dont do your fuel filter...most likely it isnt bad
Owen_TJ is offline   Quote
Old 02-16-2012, 01:56 PM   #16
Jeeper
 
Join Date: Sep 2011
Posts: 21
When i get the money I'm going to get a whole new intake(K&N) and hopefully and exhaust system. Just don't know what yet. Hopefully it will give me some power and better fuel efficient
jwrangler98sahara is offline   Quote
Old 02-16-2012, 02:03 PM   #17
Jeeper
 
Owen_TJ's Avatar
 
Join Date: Sep 2010
Location: Denver, CO
Posts: 4,356
It wont...

and if you do any wheeling, an open element filter wouldnt be the best option to choose. If anything, just put a drop in filter in it...that is what i have done. You can read thread after therad about the good and bad of the drop in but after taking my intake tube off and cleaning it after a year with the kn filter, i dont notice any change in debris from the stock.

as for exhaust...i just have a new muffler and cat in order to flow a bit better with the filter...not gonna give you power or mpg though so if thats what you're buying it for, save your money. Also dont even look at a "chip"

I didnt get more power or mpg but it did strengthen my midrange a bit where i didnt have to downshift where i once did when going uphill or around a corner...
Owen_TJ is offline   Quote
Old 02-16-2012, 02:06 PM   #18
Jeeper
 
Dextreme's Avatar
 
Join Date: Oct 2011
Location: Oregon City, OR
Posts: 4,134
Images: 1
Quote:
Originally Posted by JakesTJ View Post
^thats what im saying George
Yea you need a new speedometer gear for 33" tires...without it it makes your odometer read less. You say 172 miles, could be closer to 250 more or less??

Yep...one trick I heard that is if you tires are 20% bigger (measure "rollout") than stock, then multply the 20% back in. Not exact, but closer (gearing and lift are still variables).

172miles/17gallons = 10.11

10.11 * .20 = 2.022

10.11 + 2.022 = 12.1 mpg
__________________
'99 Chilli Pepper TJ Wrangler "Mistress"
33x12.5 DuraTracs
Zone 4.25"
Dextreme is offline   Quote
Old 02-16-2012, 02:08 PM   #19
Jeeper
 
JakesTJ's Avatar
 
Join Date: Jan 2012
Location: Holly, MI
Posts: 49
Quote:
Originally Posted by Dextreme View Post
Yep...one trick I heard that is if you tires are 20% bigger (measure "rollout") than stock, then multply the 20% back in. Not exact, but closer (gearing and lift are still variables).

172miles/17gallons = 10.11

10.11 * .20 = 2.022

10.11 + 2.022 = 12.1 mpg
I learn something new every day here!! I will have to do that with my own...
JakesTJ is offline   Quote
Old 02-16-2012, 02:11 PM   #20
Jeeper
 
Waterlogged11's Avatar
 
Join Date: Oct 2011
Location: CT
Posts: 78
I have a stock 04 rubicon 5 speed and i just did my mpg calculation and im only getting 13.5 mpgs. I did also go wheeling in that tank of gas so i could be a little higher than that if i stayed on road. once i do my 4" lift and put 33's on im sure ill be right around you. i wouldnt start changing out a bunch of stuff untill you get your speedo reading properly. you are actually traveling further and putting more miles on it than the speedo thinks which will then give you a lower mpg. like the others have said you could be putting more like 200-250 miles on it per tank. First thing first- get your speedo reading properly.
Waterlogged11 is offline   Quote
Old 02-16-2012, 02:21 PM   #21
Jeeper
 
Dextreme's Avatar
 
Join Date: Oct 2011
Location: Oregon City, OR
Posts: 4,134
Images: 1
And by "rollout", I mean the distance a tire will roll in 1 complete revolution. Might be the same as measured circumference, but might be a little difference due to PSI or tire flex. But a 33" tire will travel farther in 1 revolution than a 28" time.

Example as measured with Pi

d * Pi = c

28" diameter tire * 3.14 = 87.92"
33" diiameter tire * 3.14 = 103.62"

~15% increase in rollout

(If I did the math right)
__________________
'99 Chilli Pepper TJ Wrangler "Mistress"
33x12.5 DuraTracs
Zone 4.25"
Dextreme is offline   Quote
Old 02-16-2012, 02:29 PM   #22
Jeeper
 
Hammerdown's Avatar
 
Join Date: Jan 2012
Location: Pennsylvania
Posts: 215
Use GPS to measure distance driven. Beats speculation and trial and error.
Hammerdown is offline   Quote
Old 02-16-2012, 02:35 PM   #23
Jeeper
 
Rubicondon53's Avatar
 
Join Date: Feb 2011
Location: pennsylvania
Posts: 1,588
I'm running a 2" lift and 1" body lift on 33s.. For every 100 miles the odometer reads, I've actually traveled 106.. When my speedo reads 65 I'm actually rolling at 68.5.. My MPGs fell off gradually down to around 12. I took the throttle body off, disassembled everything, cleaned everything thoroughly, reassembled, installed. Ditched the CAI, put the stock box back on, and now I'm getting 16 to 17 MPG.... Fully loaded with camping gear and trailer I get 14 mpg.. Dumping the CAI, and keeping the throttle body clean will help.. With the CIA on the computer sensed more oxygen coming in, so it compensated by running a bit rich... Just my 2 pennies
__________________
04' Rubi, with all the gizmos we need for long range excursions, / home modified excursion trailer;

96' Lexus 450, locked, loaded and ready to roll..
'12 VW New Beetle
Rubicondon53 is offline   Quote
Old 02-16-2012, 05:07 PM   #24
Jeeper
 
SirGeorgeKillian's Avatar
 
Join Date: Mar 2011
Posts: 1,282
Images: 2
Quote:
Originally Posted by jwrangler98sahara
When i get the money I'm going to get a whole new intake(K&N) and hopefully and exhaust system. Just don't know what yet. Hopefully it will give me some power and better fuel efficient
You will waste every penny. First, get your spedo fixed and see what you are really getting. Then if needed, regear.
__________________
Check out my videos:
http://www.youtube.com/user/TrailRatedCustoms/videos
SirGeorgeKillian is offline   Quote
Old 02-16-2012, 05:28 PM   #25
Jeeper
 
owen3544's Avatar
 
Join Date: Jun 2011
Location: Nashville, TN
Posts: 137
Quote:
Originally Posted by sirgeorgekillian View Post
you will waste every penny. First, get your spedo fixed and see what you are really getting. Then if needed, regear.
^this
__________________
2000 2.5L 5speed, 8.8 & D30w/chromo shafts & spartan locker, 4.88's, UCF UHC TT, Currie front Anti-rock, Currie adj arms, 4" springs, 1.5"BL, Currie steering, RE front/rear track bars, SYE/CV, 35" MT MTZ, 15x8 beadlock wheels
owen3544 is offline   Quote
Old 02-17-2012, 07:15 AM   #26
Jeeper
 
Rubicondon53's Avatar
 
Join Date: Feb 2011
Location: pennsylvania
Posts: 1,588
Quote:
Originally Posted by SirGeorgeKillian

You will waste every penny. First, get your spedo fixed and see what you are really getting. Then if needed, regear.
Agreed 100%.. I swapped the CAI out of my old 4 banger to the i6 with less than 100 miles on it.. At 55,000 miles I did a ton of research, ditched it, and am actually getting better MPGs. I've laid out the math for him on an earlier post. You can lead a horse to water but you cannot make him drink,,,,,, Even after splashing water on his nose!!
__________________
04' Rubi, with all the gizmos we need for long range excursions, / home modified excursion trailer;

96' Lexus 450, locked, loaded and ready to roll..
'12 VW New Beetle
Rubicondon53 is offline   Quote
Old 02-17-2012, 10:50 AM   #27
Jeeper
 
Join Date: Sep 2011
Posts: 21
What is CAI
jwrangler98sahara is offline   Quote
Old 02-17-2012, 10:56 AM   #28
Jeeper
 
JakesTJ's Avatar
 
Join Date: Jan 2012
Location: Holly, MI
Posts: 49
Quote:
Originally Posted by jwrangler98sahara View Post
What is CAI
Cold Air Intake
JakesTJ is offline   Quote
Old 02-17-2012, 10:56 AM   #29
Jeeper
 
owen3544's Avatar
 
Join Date: Jun 2011
Location: Nashville, TN
Posts: 137
Quote:
Originally Posted by jwrangler98sahara View Post
What is CAI
Cold Air Intake
__________________
2000 2.5L 5speed, 8.8 & D30w/chromo shafts & spartan locker, 4.88's, UCF UHC TT, Currie front Anti-rock, Currie adj arms, 4" springs, 1.5"BL, Currie steering, RE front/rear track bars, SYE/CV, 35" MT MTZ, 15x8 beadlock wheels
owen3544 is offline   Quote
Old 02-29-2012, 12:21 AM   #30
Jeeper
 
Zephyr1298's Avatar
 
Join Date: Dec 2011
Location: North Canton, oh
Posts: 132
I got bigger tires then stock and how I measure the difference is by a gps. I'm averaging 0.8 miles more for every 10 miles on the odometer. So I calculate it like this.

Say the odometer says 214 miles and u fill up with 14.933 gallons of gas.

214 odometer miles \ 10 = 21.4

21.4 x 0.8 = 17.12 < extra miles due 2 tires

214 + 17.12 = 231.12 actual miles

231.12 / 14.933 gallons pumped

= 15.477 mpg.

__________________
1995 Jeep Wrangler yj
2.5L 4 cylinder

-(O|||||||O)-
.....J e e p.........
Zephyr1298 is offline   Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
MPGs NMRubicon JK General Discussion Forum 7 02-12-2012 10:15 PM
MPGs with a lift JimmEC JK General Discussion Forum 6 06-23-2011 10:50 PM
I smell gas and I am losing MPGs paul.b.pitts YJ General Discussion Forum 8 03-24-2010 05:40 PM
Mpgs!! IndyJeepMan TJ General Discussion Forum 4 01-19-2010 12:20 AM
How many mpgs??? silverhero2005 TJ General Discussion Forum 9 01-13-2009 08:58 AM



Download our Mobile App

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 08:47 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC