Poor Gas Mileage (2005 4.0 Automatic)

[Ledbazooka]

I recently purchased a 2005 TJ about two weeks ago with the 4.0 Automatic. I started using it mostly on the highway as I have 2 other vehicles and noticed my tank is emptying quick. I'm going to check the mileage before and after fill ups to determine the approximate gas mileage, but I'm assuming it's going to be poor.

I had noticed a sulfur smell several times driving in which I may investigate the Cat. a lil further, it runs great etc. The TJ has only 95k miles on it currently and it's all stock with no lift and with normal sized tires etc. Just asking around if anyone else notices poor gas mileage on a 4.0 or is it just me. I hope it's not a real gas pig, who woulda thought.

 

[GoldenGorilla]

Looks like the tires are somewhat close to stock size, maybe the Rubicon spec 245/75R16. You should expect to be around 15-17 mpg.

 

[Ctdriver86]

Hand calculate and let us know what you come up with. Despite this thread below, jeeps don’t really get great mpgs.

https://wranglertjforum.com/threads/42-mpg-in-a-tj.84849/

 

[Ledbazooka]

Hand calculate and let us know what you come up with. Despite this thread below, jeeps don’t really get great mpgs.

https://wranglertjforum.com/threads/42-mpg-in-a-tj.84849/

Ok, I'll do it soon.

 

[JMT]

12mpg?!

 

[Ledbazooka]

12mpg?!

Highway?

 

[Ashim]

The 42RLE auto with 3.73 gears (assumed) don't put the engine rpm in an efficient range. Also the faster you go (anything over 55) mileage falls off due to poor aerodynamics. People don't buy Jeeps for gas mileage.

 

[CreepinDeth]

I hope it's not a real gas pig, who woulda thought.

Just about anyone that verified it before buying it.

13mpg city, 16mpg highway - and yes it gets worse when 4WD is engaged on winter blend fuel.
https://fueleconomy.gov/feg/Find.do?action=sbs&id=21424

It would help if you actually hand calculated your MPG over the course of a tank of fuel, and then reported your findings.
Driving 30 miles and reporting back isn't going to tell anyone much of anything.

I drove our 2003 4.0L 5sp back from Daytona Beach FL back to Chicagoland and got 15 mpg highway on OEM sized wheels.
I was also doing 75-80mph average in a box shaped brick, and the steering was loosey goosey ass pucker factor

Once my CEL came on in Tennessee, the last leg of the trip I got 12-13 mpg because it wasn't running right.
This is a toy for my kid once he turns 16 ( he was 9 when I got it for him)

 

[TheBoogieman]

I know a guy that gets 42 mpg.

bohuggabee​

TJ Enthusiast​

Original poster
Joined Oct 29, 2018 Messages136
Location colorado

 

[Vtx531]

Just about anyone that verified it before buying it.

13mpg city, 16mpg highway - and yes it gets worse when 4WD is engaged on winter blend fuel.
https://fueleconomy.gov/feg/Find.do?action=sbs&id=21424

Exactly haha.

Plus a Rubicon is worse. Maybe take another 5% hit for age/mileage, you are looking at 11 city / 14 highway

 

[tr21triton]

I know a guy that gets 42 mpg.

bohuggabee​

TJ Enthusiast​

Original poster
Joined Oct 29, 2018 Messages136
Location colorado

the miracle of a FRAM oil filter

 

[Ledbazooka]

I know a guy that gets 42 mpg.

bohuggabee​

TJ Enthusiast​

Original poster
Joined Oct 29, 2018 Messages136
Location colorado

I saw that thread.

 

[Larry L TJ]

Have you checked the condition of your spark plugs yet. I have an o4 that was getting about 11MPG when I first bought it. I checked the plugs, Autolite and they were new, but gapped on .058. I put NGK back in and gapped on .035. Was getting 14/15 (highway). Should be a sticker under the hood on drivers' side that tells what plug and gap from the factory.

 

[Ledbazooka]

Have you checked the condition of your spark plugs yet. I have an o4 that was getting about 11MPG when I first bought it. I checked the plugs, Autolite and they were new, but gapped on .058. I put NGK back in and gapped on .045. Was getting 14/15 (highway). Should be a sticker under the hood on drivers' side that tells what plug and gap from the factory.

No not yet. Thanks, I'll take a look.

 

[B1Toad]

It takes at least 10 fillups to get a reasonably accurate average, individual fillups can have big swings from lots of factors. I think I'm doing better than most here with my 30" tires, stock ride height and manual transmission. City and highway combined and I tend to take it easy, don't speed much and I coast when I can see everyone ahead is slowing or stopped at the light, no sense getting there early just to wait. Not only saves fuel but wear and tear.

 

[Ledbazooka]

Have you checked the condition of your spark plugs yet. I have an o4 that was getting about 11MPG when I first bought it. I checked the plugs, Autolite and they were new, but gapped on .058. I put NGK back in and gapped on .045. Was getting 14/15 (highway). Should be a sticker under the hood on drivers' side that tells what plug and gap from the factory.

Haven't checked plugs yet, I just did the oil change. Dam it was so easy.

*You sure you gapped the plugs to 0.45? It calls for 0.35 gap. Please advise.

 

[cliffish]

The MPG will never even be good, but the Smiles per Gallon more than make up for it. BTW great looking TJ and a great color!..Welcome from LI, NY.

 

[DuckNut]

Who cares...support your American oil workers!

 

[KennethS]

Haven't checked plugs yet, I just did the oil change. Dam it was so easy.

*You sure you gapped the plugs to 0.45? It calls for 0.35 gap. Please advise.

You need another zero in there: 0.045” or 0.035”.

A 0.010” difference is plug gap won’t really make a difference.

 

[Larry L TJ]

Haven't checked plugs yet, I just did the oil change. Dam it was so easy.

*You sure you gapped the plugs to 0.45? It calls for 0.35 gap. Please advise.

TYPO. It is .035