Jeep O2 sensor question

[moose3840]

Help! Have a 98 Jeep TJ with the 4cyl engine. The upstream O2 sensor had thrown a code showing the Jeep was running rich. Which it was as evidenced by the black soot under the tailpipe when cranked as well as the smell of raw gas and the horrible gas mileage. It was replaced and all seemed well. Jeep has power(For that motor) seems to be running clean but is throwing the same code. I replaced the O2 sensor again just in case I had gotten a bad one. So on it's third O2 sensor it seems to run fine. However, it keeps saying it is running rich.
Anyone had this problem and what did you do to fix it.
Thanks
Moose

 

[moose3840]

Upstream O2 sensor.

 

[Junior_357]

Might want to clean the throttle body, and check the mass air flow sensor. Also check the intake air temperature sensor. I've seen the IAT fail and tell the computer that the air is cold even in the middle of summer, which causes the rich condition.

 

[brad sweet]

yep check the mass air flow sensor and make sure that all the air plumbing is on correctly..if you added a cold air kit or any other intake changes such as K&N filter ..clean mass airflow with electronics cleaner to remove excess oils from sensor....if it runs to rich too many times you may have a stopped up converter or will soon...check all hose connections

 

[Lobo1]

yep check the mass air flow sensor and make sure that all the air plumbing is on correctly..if you added a cold air kit or any other intake changes such as K&N filter ..clean mass airflow with electronics cleaner to remove excess oils from sensor....if it runs to rich too many times you may have a stopped up converter or will soon...check all hose connections

Jeep 4 cylinders are prone for the catalytic converter to clog up. Early signs are exactly what you described.