TJ mileage - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

Reply
 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 06-21-2003, 10:45 PM
**DONOTDELETE**
Guest
 
Posts: n/a
TJ mileage

I recently purchased a 1997 jeep TJ, with 4.0 liter 6cyl. engine and automatic transmission. The odometer is currently reading 62,000 miles and the motor was recently tuned.I am running 32-11.50- 15 LT tires(inflated at 35 p.s.i.) the vehicle is otherwise stock.I am averaging 155 miles per tankful,(city) considering it has a 15 gallon gas tank ,this equals to a little more than 10 miles to the gallon. This seems like terrible mileage for a six cylinder vehicle.My question is this: Is this mileage normal for this vehicle or is their some miscalculation in the odometer due to the oversized tires and if so how do I recalculate the mileage taking into account the larger rubber.What upgrades are on the market to better the mileage on the new TJ wranglers.
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 06-22-2003, 12:57 AM
Veteran
 
babypoo's Avatar
 
Join Date: May 2003
Location: Milwaukee(which is algonquin for the good land)WI U.S.A
Posts: 755
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: TJ mileage

That's alot of air pressure even for street pressure I run between 25-27# but that won't help your gas mileage. O.K. to answer your first question... yes it does affect your speedometer and your odometer, the only way I know of recalibrating it, is Superlift and one other manufacturer(can't remember the name) make a speed sensor calibrator. JC Whitney sells the Superlift brand one for $179.95, part #AKB487486Y. Second question... I have a 4cyl with 32's and that's about the same mileage I get(per mile I have a larger tank). What gears do you have and do you have a manual or auto tranny? The three speed auto if you have it is not helping matters either. Third Question...There are multiple things you can add to your Jeep to help fuel mileage (or so the adds say) I installed a TB spacer on mine and noticed a minor difference that's about the only thing I've done that is supposed to help. But if you put a post up I'm sure others will have suggestions.
Hope this helps,
John
[email protected]
babypoo is offline  
post #3 of (permalink) Old 06-22-2003, 01:40 AM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: TJ mileage

Good greif that is much worse than normal. My Bro-in-law's stock 97 TJ with a 5-Speed has a range of almost 300 miles in mixed driving any my heavily modified YJ with a 5-Speed can pull down 260 miles in mixed driving.

If your tranny isn't shifing crisply, your torque converter might be slipping enough to waste a whole lotta fuel.

Try a complete tranny fluid flush and put in some synthetic (Mopar approved) ATF in it and see if the mileage improves.

BTW the estimated stock fuel consumption for your year is 17city 19highway for comparisons sake.

Give Advance Adapters a call to find the correct speedo gear straight from Mopar. Thy have several options for the NP232 T-Case. They usually run about 12 bucks.

Hope this helps
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 06-22-2003, 01:47 AM
Veteran
 
babypoo's Avatar
 
Join Date: May 2003
Location: Milwaukee(which is algonquin for the good land)WI U.S.A
Posts: 755
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: TJ mileage

He's calculating his mileage off of the odometer which is also offset by the larger tires. His true fuel mileage is better than he's saying.
John
babypoo is offline  
post #5 of (permalink) Old 06-22-2003, 01:50 AM
Keyboard Implanted
 
jamgood96's Avatar
 
Join Date: Jun 2000
Location: Tualatin, Oregon, United States of America, North America, Earth, Milkyway Galaxy, Universe...
Posts: 3,932
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: TJ mileage

35psi is way too high to be running. That's probably what the recommended max pressure is. I run 24 on the street in my '93 YJ. Try dropping it to around 26-28 or so. As for your MPG you're getting, like said, you need a new speedo gear. There are a couple of online sites that will help you figure out how many teeth you need on your new gear to correct your speedo. Here's one I found on a quick search. Hope it helps.

Speedo Calibration

As for what you can do to up your MPG, I'm not really sure what can help you in that department. There are plenty of mods to do to the motor, but most are performance mods, and may or may not help your MPG. I'd say slap on a throttle body spacer for starters, and maybe upgrade to a K&N filter. Also, keeping your foot out of the skinny pedal is a sure way to help with the MPGs.
jamgood96 is offline  
post #6 of (permalink) Old 06-22-2003, 08:17 AM
Keyboard Implanted
 
GeeAea's Avatar
 
Join Date: Sep 1999
Location: Pottstown, PA
Posts: 2,076
Thanks: 0
Thanked 1 Time in 1 Post
 
Re: TJ mileage

Here are some more.

These sites do not all agree. Keep in mind that some of them may be calculating as though the tire was measured as labled (i.e. a 33" tire is rarely 33" etc.) Also the dealer tells me that there are no odd # gears between 32-36 or 32-38. If you need addtional adjustment the dealer can use the DRB2 scanner to correct the speedo further ...or they can do the whole thing without a gear change.


You've got issues beyond speedo error. You should also have a 19 gallon tank. The 4.0 with an auto around town will be a gas hog. Heck my daughter gets our SE down to 12.5 mpg (it's a 4 cylinder). She manages to challenge V8s for economy. I imagine that the 4.0 would be slightly worse.

Heck ..you're in BIG BLOCK range ...but I'd have a hard time imagining the thing consuming that much fuel without some apparent operational problem (like a Check Engine Light).

Ah!!! The 97 should have the on-off-on-off-on key thingie diagnostic feature. These codes should work for you.
GeeAea is offline  
post #7 of (permalink) Old 06-22-2003, 07:28 PM
Way Outta Control
 
Join Date: Sep 1999
Location: The Palouse
Posts: 13,432
Thanks: 1
Thanked 3 Times in 3 Posts
 
Re: TJ mileage

1. Welcome to the forum.
2. Thanks for filling out your user profile.
3. Read the New Posters Message at the top of the forum.
4. Participate more often!
5. Two brains are always better'n one!
6. You may want to think about:[*]Air input upgrades [*]Freeflow Exaust
7. Even with miscalculation... the mileage seems low.
LEVE is offline  
post #8 of (permalink) Old 06-22-2003, 09:02 PM
 
Join Date: Mar 2003
Posts: 291
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: TJ mileage

The 97 was the first year of OBD II so the on- off- on- off thing doesnt work, go to autozone for a free diagnostic.

as for the mileage, its all how you drive it!!! I live in Michigan and the speed suggestion is 70mph, which means if you go slower than 75, you get run over. Well, most of my driving on road is on the highway, those four angry squirels under the hood want lots of go juice when you work the engine that hard. I am lucky to get 18mpg. That is stock. Not good. I run a K&N air filter too. The people I know here with 4.0's get roughly 14-15 mpg. There are MANY factors that affect fuel economy.
How much ethanol does your state require in the gasoline, temperature, etc.....

Phil
newbie24x4 is offline  
post #9 of (permalink) Old 06-22-2003, 09:38 PM
Keyboard Implanted
 
GeeAea's Avatar
 
Join Date: Sep 1999
Location: Pottstown, PA
Posts: 2,076
Thanks: 0
Thanked 1 Time in 1 Post
 
Re: TJ mileage

Are you sure about that? I've had this debate before. In fact before I learned that OBDII was adopted in 96 ..I argued that the 98 was the first OBDII because soooooooo many 97 owners had used the on-off-on-off-on feature. Hence I assumed that this was not OBDII since it shared the same flash codes as earlier OBDI vehicles.

So is this "true knowledge" ...or just assumed (like mine was of 97s being OBDI)????
GeeAea is offline  
post #10 of (permalink) Old 06-22-2003, 09:45 PM
 
Join Date: Mar 2003
Posts: 291
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: TJ mileage

Well I have a 97 and it has OBDII, Not sure if it was adopted later in the year, or if you can do both? But I KNOW that I used the OBDII to diagnose my Jeep.

Phil
newbie24x4 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



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 On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome