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Fuel Mileage

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Old 03-07-2009, 02:03 PM
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Default Fuel Mileage

So i just worked out my fuel economy from full tank to the fuel light coming on, and from city driving I'm getting 8.91 MPG. iThis seems pretty low for a 4.0L I6. Is this normal? If not, why would be causing it to be so low? Mabe something to do with the O2 sensor? I don't bag on it either, 3/4 throttle at the odd time, but that's about it. What is everyone else getting?
Old 03-07-2009, 02:05 PM
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Originally Posted by brntrbbr
So i just worked out my fuel economy from full tank to the fuel light coming on, and from city driving I'm getting 8.91 MPG. iThis seems pretty low for a 4.0L I6. Is this normal? If not, why would be causing it to be so low? Mabe something to do with the O2 sensor? I don't bag on it either, 3/4 throttle at the odd time, but that's about it. What is everyone else getting?
Clean your TB and then Seaform the intake. Change all sensors. You should be getting around 15 if the motor is in good shape.
Old 03-07-2009, 02:48 PM
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Well I seafoamed via the TB about 5 days ago, so that takes care of the first 2. So what's included in "All Sensors?" O2 and...
Old 03-07-2009, 03:49 PM
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Yea, thats not good especially for a 2000. I am getting between 13 - 16 on average on my 94 with 145k which sucks, but I guess it is what it is.

When I cleaned my TB I actually removed it as well as the IACV valve and cleaned the TB with carb cleaner and a toothbrush. I actually did it due to a starting issue, but it cant hurt for maint reasons either.

If it were mine I would change the plugs. I dont think there are wires ir a cap / rotor since it has coil packs so cant do that. Fuel filter is in the tank so if you are really motivated that can be changed.

Hows your air filter?

Dont know about he O2's. I just replaced mine because I think it was original and did it just because. It looked nasty when I pulled it out but havent had the new one in long enough to see if it actually makes a difference in the MPG area.
Old 03-07-2009, 03:58 PM
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Any gas smell around the vehicle?
could be a gas leak
Does it seem like it doesnt want to move easy?
could be the parking brake has seized or a drive train problem
Any whistling or sucking sounds under the hood?
possible vacuum leak

Check the smell of the exhaust, you could have a misfiring cylinder which will push unburnt fuel out the exhaust. This would also be apparent by a loss in power (which you may not realize is there if you recently purchased the vehicle) and a rough idle.
Old 03-08-2009, 09:44 AM
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Air filter is new
No power loss
Exhaust smells normal, don't think it's running rich
No gas leaks
The engine has 285K on it, bit it is in pretty good condition. No oil buildup on the exerior of the block etc.
The plugs would affect the fuel mileage even if there is no noticeable power loss?
Old 03-08-2009, 09:54 AM
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don't replace all sensors. the front oxygen sensor is supposed to effect gas mileage. i replaced mine cuz it was original, along with major tune up and fuel filter. my gas mileage didn't improve, i get 13 in the city, but also get 20 on the hwy by driving right.

yours is low, the first step is state of tune. cap, rotor, plugs and wires, don't skip any of the items. i don't think your 2000 has a fuel filter serviceable, air filter was already stated. make sure 4 wd isn't staying in, which is kinda dumb to say, i'm sure you'd know that. tire pressures right. after that i'd do the oxygen sensor.
Old 03-08-2009, 04:14 PM
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Originally Posted by brntrbbr
Air filter is new
No power loss
Exhaust smells normal, don't think it's running rich
No gas leaks
The engine has 285K on it, bit it is in pretty good condition. No oil buildup on the exerior of the block etc.
The plugs would affect the fuel mileage even if there is no noticeable power loss?
Plugs are cheap, I paid $10 for all 6. Just go ahead and do them.

285k on a 2000? Thats a lot of miles.
Old 03-08-2009, 04:21 PM
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Originally Posted by jpdocdave
don't replace all sensors. the front oxygen sensor is supposed to effect gas mileage. i replaced mine cuz it was original, along with major tune up and fuel filter. my gas mileage didn't improve, i get 13 in the city, but also get 20 on the hwy by driving right.

yours is low, the first step is state of tune. cap, rotor, plugs and wires, don't skip any of the items. i don't think your 2000 has a fuel filter serviceable, air filter was already stated. make sure 4 wd isn't staying in, which is kinda dumb to say, i'm sure you'd know that. tire pressures right. after that i'd do the oxygen sensor.
He doesn't have a DIZZY he has coil packs and they AINT CHEAP!!!
Old 03-08-2009, 06:41 PM
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City 11-10 highway 11-14 it sucks bad
Old 03-09-2009, 07:06 AM
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So I'm ordering up an Air Filter, 02 Sensor, and a Fuel Filter if it is serviceable, from my sponsor. Hopefully this will make a difference
Old 03-09-2009, 09:19 AM
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Why is everyone getting so low? I just checked my highway consumption and I got 22.xx on my 96. I still have to replace the plugs, wires, and dizzy, and my tires are probably a bit low on air.

s
Old 03-09-2009, 09:31 AM
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I have been averaging about 17-18 miles pretty much all winter with 10 minute warm ups......I drive basically on gravels all the time...im also stock though
Old 03-31-2011, 08:38 PM
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Hi,

So to make a long story short I never could around to replacing the O2's and fuel filter, but I will be for sure later in April.

I would like to know if anyone can give me some info on how to replace the upsteam O2 sensor, as well as the fuel filter.

(I'm across the country right now, so I can't really look at my jeep for myself to see the locations)

Much appreciated!

P.S. I'm at over 320 K now and it's still purring like a kitten.
Old 03-31-2011, 08:48 PM
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Seafoam at the TB only gets the intake and valves. You need to run some through the tank to get the injectors.


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