FIRST OFF i have searched everything i read bangs heads with the thread that i read before that one
OK ive got a 98 jeep cherokee with a 4.0 has 193k miles and around 60k on motor.
Before i got it they have a flowmaster muffler on there... but there is only 1 oxygen sensor that i can see (seems as it would be before the cat.)
I am only getting 10mpg city... SOOO
Should i try to reset my computer?
OR should i throw another o2 sensor to act as a after cat sensor, OR should i replace the o2 sensor thats on there now?

please help money is tight and i dont want to have to go step by step if someone has a good answer

 

Well if there is indeed only one o2 sensor then that's good. Dunno year they went from one to two. O2 sensors are synonymous with bad mpgs. Get your rig on a code reader to see if There's any codes that have stored in there and not tripped the CEL before you buy anything. Any bond auto type place will do it for free and any good shop will too.

 

My '96s have (2) O2 sensors. The sensor between the engine and CAT is the important one concerning fuel mileage.

 

my 98 only has one 02 sens.

 

98's don't really like having the Cat removed... just a heads up. May wanna put one back on it with an after cat o2 like it originally was. Can still run your flowmaster behind it... I do.

 

When i look up parts for my year/model it says upstream and downstream so im guessing i should have two also...... so if the important one is upstream then im good to go....

 

maybe ill see if i can find a shop with a code reader...
My mpg is horrible
i mean i do have 7 inches of lift and 35s but still there is guys on here supposebly getting 14 mpg with the same setup
someone please help
(ive already redone the plugs/wires, k&n Airfilter) all thats left is the dist. cap

 

I would suggest doing a compression test to see the general health of the engine and go from there.


Cost you nothing if you rent a compression test kit from autozone or oreilly.

GL.

 

Just did a code reader...
Im throwing
1) a o2 sensor code (maybe because i dont have the downstream but a couple people told me that the 2nd one doesnt have anything to do with the gas mileage)
2) ignition switch code (ive got a new one to go in already)
3) misfire????? what should i do to fix this?

 

no one?

 

Dist cap