I have a 1995, automatic, 4.0 4x4. I believe there's only one oxygen sensor in addition to the cooling sensor.

2-3 mechanics tell me that they both check out O.K. when the vehicle is connected to a computer. However, I get low mpg and.... weak idle irregularly and a consistent sense that my Jeep doesn't get a good air mixture (just my inexperienced opinion based on listening to an engine).

So, for about $75, I think it's worth replacing them both. This Jeep was not run daily in the past and was not well maintained. I'm pretty certain neither sensor has ever been replaced and I've driven this Jeep just after having a new set of spark plugs in it (no change in performance or feeling).

I don't know where these sensors are located and I'm on assuming that there are only the two of them.

Any links to info sites on my cherokee or any advice regarding my problem and the description above are appreciated.

 

The o2 sensor is located in your exhaust pipe before the cat. Coolant temp sensor is near the thermostat housing on the front of the motor.

Parts stores should have pics for you.

 

MrPants, the desription of your symptoms sound more like a vacuum leak than a bad sensor, to me. The vacuum line going from the throttle body to the MAP sensor (on the fire wall behind the engine) is notorious for coming off or developing crack and leaking. Give all your vacuum lines a good looking over. Vacuum lines really dry out and crack often on rigs that are left sitting for a long time.

 

Good way to find a vacuum leak is to spray starting fluid on the vacuum hoses one at a time. If the engine rpms increase you found a leak.

Gotta have the motor running, btw...

 

I have had the vacuum pressure checked twice.... the needle bounces a lot--but not too dramatically. I suppose mechanics could overlook something when doing a vacuum test???

 

not vacuum checked ,checked for vacuum leaks big difference

 

If the needle is bouncing on the vacuum gauge that means you have an intake valve that is not sealing, that would cause a crappy idle and fuel mileage.

 

or eratic idle will cause vacuum to be jumpy also versa visa visa versa