Gas Mileage

B

Blackash132

NAXJA Forum User
Location
St. Louis, MO
Ok I have searched and found that replacing the O2 sensors helps mileage... I replaced both and have a flowmaster 50series 2.5 inch piping from the manifold and a high flow carsound cat. 62mm throttle body, tbspacer, and rusty's kn filter. 4.0 2000 xj
Why am I only getting 200miles per tank nomatter if it's all hwy or city??? ps i have 30x9.50 bfg a/t's what gives please help...
blackash
 
Rocks in your tank?

Something is definetely wrong (or you have a very big foot?).


My 97 gets about 15-18mpg and I have no mods...not even a K&N.

No check engine light? Run rough? No other signs of trouble?
 
Next time you fill up from empty check your gallons. You should be right around 18gal give or take. If infact your geting 18gal fill ups your getting around 11mpg.
 
Is your mileage correct as per GPS or hwy mile markers? If not, you need to change your speedo gear for your tires as you are currently getting better mileage than you think.
 
the most i ever filled up... even topping off i only got 17 gal in according to the pump plus i ran out of gas pulling up to the pump. I have no other troubles does anyone think it could be a bad map sensor? no check engine light... thanks again

blackash
 
I would also try gas from a different place. Try Mobil or BP. I was getting those mileage numbers from my usual gas place and when I switched it went back to normal. It can't hurt!
 
map isn't the problem it would be running ruff it it was the map after warm up.what all does your jeep have the tire size you have shouldn't efect the tripomiter that much.do you have a bumper,roofrack tire on top.that is the stuff that will kill milage
 
yes i have a roofrack with a tire on it, but it has been getting this bad of mileage ever since i got it bone stock. I thought that the exhaust replacement and new filters and sensors would make a difference cause i got the xj from michigan and the exhaust was a little rusty... but it hasn't made any improvement yet. I reset the battery and i haven't gotten through the tank yet so that might still do the trick... thanks for the map info lilBlue
 
Bumpers, Racks, And Roof Mounted Tire shouldn't have too much effect on it. MY Jeep has all of the above including a 33x12.5 spare in the roof rack and it still gets 15-18mpg.

I would start checking the basics...

spark plugs, vacuum leaks, compression check, etc if it doesn't get better.

And I would second trying a different brand of gas...I see at least on car a months that has poor running conditions and bad fuel mileage that is due to the brand of gas..usually ARCO.
 
DeftwillP said:
Is your mileage correct as per GPS or hwy mile markers? If not, you need to change your speedo gear for your tires as you are currently getting better mileage than you think.
Click to expand...

Not exactly... the 97+ XJ's with 30" BFG all terrains are dead on for speedo accuracy. I have them and it's GPS accurate.
 
Ok Ok i reset my computer by disconnecting the battery. I let it run untill I was almost out of fuel and putting to the gas station. my trip meter and odometer were the same I got 213 miles to one tank again. I filled up with 18 gallons this time at a Mobile. What else can it be? my 30's were dead on with hwy mile markers too so my speedo is fine. I read all these stories with you guys with 35's and 4.88's and you are getting 16 and 17 mpg and it's very depressing. The best mileage ai ever got (including when it was bone stock) was the day after I replaced my front O2 sensor on my way back to st. louis from colorado I got 260miles per tank, but that was Kansas with no wind and cruise control. Haven't gotten anything like that since. On the other hand my dad has a 97 xj with a roofrack and basically most of the same stuff that I do but he has 31's no changed speedo and he get better mileage than i do he can get 250 all the time. what gives?
"Help me Obe One Kenobe, You're my only hope"
 
Blackash132 said:
Ok Ok i reset my computer by disconnecting the battery. I let it run untill I was almost out of fuel and putting to the gas station. my trip meter and odometer were the same I got 213 miles to one tank again. I filled up with 18 gallons this time at a Mobile. What else can it be? my 30's were dead on with hwy mile markers too so my speedo is fine. I read all these stories with you guys with 35's and 4.88's and you are getting 16 and 17 mpg and it's very depressing. The best mileage ai ever got (including when it was bone stock) was the day after I replaced my front O2 sensor on my way back to st. louis from colorado I got 260miles per tank, but that was Kansas with no wind and cruise control. Haven't gotten anything like that since. On the other hand my dad has a 97 xj with a roofrack and basically most of the same stuff that I do but he has 31's no changed speedo and he get better mileage than i do he can get 250 all the time. what gives?
"Help me Obe One Kenobe, You're my only hope"
Click to expand...

I'm feeling your pain also. I'm getting about 200-250 miles to a tank. I've got 31"s with a 3" lift. What gives?
 
Are you doing mostly stop and go in town driving, or checking from highway driving? 213mi out af a 17gal tank (12.52mpg) is about normal for mostly city driving.
 
hwy or city, it's all the same, if i take a trip out of town and use a tank it's the same as if i go to work and back all week, within about 10-15 miles. and the tank is bigger than 17 gal.
 
I am having the same problem. 2" of lift and 235x75 all terrains. I dont understand why I cant get more than 200miles out of a tank. hwy or city I am averaging 12.5mpg. Engine sounds like it is running fine and has plenty of power. The only other things I can think of are spark plug wires and possibly map sensor.
 
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