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-   -   Gas Mileage (http://www.wranglerforum.com/f282/gas-mileage-220754.html)

mars81 02-19-2013 11:50 PM

Gas Mileage
 
OK so before everyone starts with the jeeps and bad gas mileage comments I know and understand but I'm just curious about my current mileage.

This is first TJ, had a YJ for years but haven't had a jeep in a long time. Its an '02 4.0 w/auto tranny, stock 3.08 gears and soft top. The jeep is basically stock with the exception of the tires that were on it when I bought it...not sure of the exact size but they are just under a 31" and it needed a new air filter so I bought a K&N AIT filter. I live in the city and do a lot of stop and go driving but I'm averaging like 11.5 mi/g and I just feel this is definitely on then low end. Any advice or does this sound about right?

Johnnybonkel 02-19-2013 11:55 PM

Quote:

Originally Posted by mars81
OK so before everyone starts with the jeeps and bad gas mileage comments I know and understand but I'm just curious about my current mileage.

This is first TJ, had a YJ for years but haven't had a jeep in a long time. Its an '02 4.0 w/auto tranny, stock 3.08 gears and soft top. The jeep is basically stock with the exception of the tires that were on it when I bought it...not sure of the exact size but they are just under a 31" and it needed a new air filter so I bought a K&N AIT filter. I live in the city and do a lot of stop and go driving but I'm averaging like 11.5 mi/g and I just feel this is definitely on then low end. Any advice or does this sound about right?

That is low...i just got mine and around town looking at about 18

PStov98TJ 02-19-2013 11:57 PM

How are you driving it? I get like 15 city and 16-17 highway with the 4 banger, 4.10s, and 33's.

mars81 02-19-2013 11:59 PM

I definitely don't granny it but I'm also not redlining the tach off every light.

PStov98TJ 02-20-2013 12:03 AM

I know what you mean. But even accelerating as fast as the other cars around you will knock it down. But not that much... Might want to have it checked out. Change your spark plugs out. Changed the oil lately?

mars81 02-20-2013 12:05 AM

Oil is somewhat fresh. Like a 1500 miles old. I think plugs, wires and distributor cap might be a good idea. Anyone have suggestions for what ones to go with?

duaneduanet 02-20-2013 12:58 AM

Yea something is wrong. My 1997 TJ 4.0 gets 17.5 city. 3:08 gears

mudmagnet63 02-20-2013 01:05 AM

Yep the toad got about 18+ on our trip to CO. last year with 31's and 3.07, not sure about city we dont even have a stop light here.

InvisiblePants 02-20-2013 01:17 AM

It could also be failing O2 sensors.

mars81 02-20-2013 06:37 AM

How could I test the O2 sensors? How many are on the 4.0? I haven't thrown CELs to the read codes.

tonyb11 02-20-2013 06:57 AM

im also havin this problem. i jus picked up a 04 rubicon and i know its gear a bit lower then my last sport but it seems pretty bad on gas and i baby it on road.

Steve305 02-20-2013 07:14 AM

Quote:

Originally Posted by mars81 (Post 3394452)
How could I test the O2 sensors? How many are on the 4.0? I haven't thrown CELs to the read codes.

O2 sensors will definitely richen up the mixture over time ... and way before they throw a code. Do you ever notice any fuel smells? That's a sure sign that you have a rich mixture and a problem in the system somewhere. Poor fuel mileage can be caused by several things. Replacing plugs, plug wires, O2 sensors, air filters, and other things in the system are always a good idea and a great place to start. Especially if you don't know the age of the components. O2 sensors are relatively inexpensive when compared to the possible savings in fuel costs and are somewhat easy to replace. My '98 2.5 manual consistently gets 20-22, but I drive it like a grandpa (which I am).

Patrick H 02-20-2013 08:01 AM

Quote:

Originally Posted by mars81 (Post 3393606)
Oil is somewhat fresh. Like a 1500 miles old. I think plugs, wires and distributor cap might be a good idea. Anyone have suggestions for what ones to go with?


You might want to open your hood.;) You don't have a distributor cap, or spark plug wires.:)

mars81 02-20-2013 08:10 AM

Actually yeah just did that. Haven't really had any reason( or time) to open it, so when I was out walking the dog I went down to the garage to take a loom to seen if they were OEM or not and there was nothing there lol. My old YJ had them :)

Pit Bull 02-20-2013 08:19 AM

Getting about 12.5 mpg combined here. I know why though..... I am running 235x70x15 tires on my 98 Wrangler Sahara w/ a 4.0, auto trans, and 3:73 gears. It has a 2" bb lift and once I get either some 31's or 32's on it..... maybe even some 33x 9 or 10.5"s x. 15..... if they will make them again, my mpg should go up a bit

Pit Bull

MTJeepTJ 02-20-2013 09:32 AM

mpg also depends on how much ethonol they put in your local gas. My 06 TJ gets 2 mpg better when i go outside my local county and buy non ethonol fuel. Just a thought. The pump will be marked that the fuel contains up to 10% ethonol usually if it has it in the fuel. I get 12 mpg city with ethonol and 14-15 city without it.

PStov98TJ 02-20-2013 10:08 AM

Quote:

Originally Posted by MTJeepTJ
mpg also depends on how much ethonol they put in your local gas. My 06 TJ gets 2 mpg better when i go outside my local county and buy non ethonol fuel. Just a thought. The pump will be marked that the fuel contains up to 10% ethonol usually if it has it in the fuel. I get 12 mpg city with ethonol and 14-15 city without it.

Same here! My Jeep gets probably 1-1.5 mpg better with non ethanol. That E-10 crap is not really good for the TJ engines anyway (not bad, just not good either). My Jeep runs a little smoother with the non ethanol as well. It costs a little more but it's worth it to me. Just a thought.

mars81 02-20-2013 10:29 AM

Yeah I wouldn't even know where to find non ethanol gas. Everywhere I've lived has only had the <10% mixture. I just bought some new spark plugs...now I just need to borrow a torque wrench and I'll let everyone know how it turns out.

PStov98TJ 02-20-2013 10:36 AM

Do a google search for gas stations in your area. There are comprehensive lists of all the stations that sell non ethanol gas in the country. It's better for your lawn mowers and boats too :)

mars81 02-20-2013 11:02 AM

So I searched and found this website... http://pure-gas.org/index.jsp in case anyone wants to search. But nothing in the DC metro area.

PStov98TJ 02-20-2013 11:03 AM

That's exactly what I was talking about. Used it to find stations by me in South MS.

InvisiblePants 02-20-2013 01:34 PM

Quote:

Originally Posted by Steve305 (Post 3394533)
O2 sensors will definitely richen up the mixture over time ... and way before they throw a code. Do you ever notice any fuel smells? That's a sure sign that you have a rich mixture and a problem in the system somewhere. Poor fuel mileage can be caused by several things. Replacing plugs, plug wires, O2 sensors, air filters, and other things in the system are always a good idea and a great place to start. Especially if you don't know the age of the components. O2 sensors are relatively inexpensive when compared to the possible savings in fuel costs and are somewhat easy to replace. My '98 2.5 manual consistently gets 20-22, but I drive it like a grandpa (which I am).

I couldn't have explained it better. :thumb:

mars81 04-07-2013 02:02 PM

So new plugs installed and it helped a bit but not much. As for the O2 sensor...since there is 4 of them, a certain one I should start with or is there a way to check the sensor?

Kris_R 04-07-2013 02:19 PM

I believe the two before the cat are for air/fuel, and the two after the cat are for emissions. I haven't changed mine yet, but that's what I gather in my research.

InvisiblePants 04-09-2013 12:48 AM

Quote:

Originally Posted by Kris_R (Post 3606051)
I believe the two before the cat are for air/fuel, and the two after the cat are for emissions. I haven't changed mine yet, but that's what I gather in my research.

yep the pre-cat are air/fuel. I'm glad i don't have to worry about 4 O2's. My 97 just has 2. 1 upstream and 1 downstream.

DocterWrangler 04-09-2013 07:19 AM

Quote:

Originally Posted by PStov98TJ (Post 3395180)
Do a google search for gas stations in your area. There are comprehensive lists of all the stations that sell non ethanol gas in the country. It's better for your lawn mowers and boats too :)

I work at homedepot and 90 percent of the lawn mowers that are brought in for servicing are because of "bad gas" or a fouled carb because of the ethanol content. Sta-bil works great for small engines.

Bielzebub 04-09-2013 07:32 AM

I use MFA Super Unleaded fuel in my 99 with the four banger. In the city I usually get about 16 to 18, and highway, well I don't drive highway for very far, so it's tough to estimate. I know that I can drive around town for about 4 hours and barely use 1/8 of a tank.

mars81 04-09-2013 09:02 AM

So, changing the o2 sensors. I'm going to need to jack up the jeep aren't I?

ChaddG 04-09-2013 09:07 AM

I put a k&n filter in, and put the soft top on, went from 14 mpg to 15. I will try the o2 sensors

InvisiblePants 04-09-2013 11:11 AM

Quote:

Originally Posted by mars81 (Post 3613504)
So, changing the o2 sensors. I'm going to need to jack up the jeep aren't I?

Nope. It should be tall enough to keep all 4 tires on the ground.


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