Gas Milage Woes in an '05 4.0

[prariepunk]

I've been having issues with the gas milage in my '05 TJ... like 10mpg! :x . What may be causing this?!?!?!?! I just added a snorkel but I didn't expect the drop in milage. I have a K&N air filter that doesn't need changed for another 10K. I have 4.11 gears (oil changed 2yrs ago)... there's not much room in there so I don't have much gear (a winch on front & a basic emergency kit inside)... any opinions? should I check my O2 sensors?

 

[jtm703]

Auto or manual transmission?

I rarely get better than 15 round town with my 4-speed auto, maybe 18 on the highway. I have seen it as low as 13 and 10, though.

An O2 sensor could be bad, causing the computer to add more fuel to the mix than you need. Also, if you have an auto, try a flush and fill with new filter. That helped my mileage a little. Regular shots of fuel injector cleaner can help, too. Have you looked at your spark plugs? Are the gaps set right? Do they look scored? This could indicate other problems.

Don't know if any of these are the right answer...just throwing out ideas.

 

[prariepunk]

Auto trans... looks like the O2 sensor has been changed (at least) once before

 

[TerryMason]

We've got pretty much the same Jeep.

How may tanks have you been getting 10mpg?

 

[prariepunk]

I just noticed it after I put the snorkel on... I didn't get amazing mileage before but I know it wasn't 10mpg... 30x9.50x15 AT tires, 4.11 gears, K&N air filter, 1k since oil change... auto trans... just put in a new o2 sensor, gonna see if that helps... I put in 5.25 gals so we'll see how far that gets me...