Hi I gotta 98 jeep grand Cherokee lerado 4.0 V6 4WD one day I notice my car was burning hella gas put 30 in there and and drove about 20mi and my light comes on then so a lot black smoke is comin out so I know I'm burning a lot of gas had a tune up done and put some objectors cleaner and filled it up cost me 82 dollars to fill up 4 days all of it GONE!!!!! Still black smoke and fumes of gas what THE BELL CAN I DO I'm wasting my money just by staying in my area SOMEONE HELP

 

Damn no one wanna gimmie a solution

 

I breed help

 

I would replace the o2 sensor. I ruined mine a few weeks ago and until I replaced it I was getting 5mpg and had black smoke. Now I get 17 again with clean exhaust.
Something is making the engine run way too rich, and o2 sensors do that when they fail.

 

Is it an fix that I can do myself

 

I changed mine in about 15 minutes, and it was stuck in the pipe pretty bad. A WJ may have two upstream o2 sensors though, making the job twice as expensive, though I am not sure.

 

Yea it is more than likely your o2 sensors, you could try cleaning them but it would only be around $80-85 for both of them to your door so you might as well get new ones.

 

Thanks guys I was hoping it was

 

So you got about 3 miles per gallon.
Very possible, depending on more factors than I have time to list, and you even care about reading. If you want to increase your mileage, take the radiator cap off and drive a Prius under it. Instant 56 miles per gallon!

Not trying to be a jerk, but you have told us squat. We dont even know what engine you have. I have a 5.2lt, with air on and cruise, I can coax 18.5 to 19.5 mpg. I stick my foot in it, I can get less than 8.

Your Mileage May Vary
Ron