My 1993 Cherokee with 162k miles kind of idles weird when at a stop. The engine almost jumps every now and then like it's getting more fuel than usual. I've replaced my cap, rotor, plugs, wires, ignition coil, the whole nine yards. My question was if my 02 sensor should be replaced. To my knowledge it is original(much like everything else on this Jeep). Im not sure if it should look like this.

 

Since your Jeep is pre-OBDII it's not easy to know if the O2 sensor is malfunctioning. If your engine is idling rough or weird, and you're getting really crappy mileage (less than 14 mpg) then it's probably shot. Fill your tank, reset your trip odometer, then when you refill after at least 200 miles divide the miles driven by the gallons of fuel added at fillup to see what your real MPG is.

If you need a new sensor, this is a part you MUST get from the dealer. The aftermarket ones, even the good direct fit ones including Bosch and NGK brands have a heating element that is of the wrong resistance. This causes them to heat up to slowly, and then they fail withing a few weeks to a few months. I went through this nightmare, and changed out several O2 sensors every month or so until I finally ponied up the big bucks for a MOPAR one. That was about ten years ago, and that MOPAR O2 sensor is fine and dandy to this day.

 

Ok thanks for the info. About a few months ago I calculated that my Jeep was getting around 16-17mpg before I gave her a tune up. Is there any way to test with a multimeter? Im sure after 27 years it would need replacing anyways.

 

Not that I know of.

Before you look at the O2 sensor, how about your TPS and IAC? Those have a huge effect on idle. MAP sensor, too, and check for vacuum leaks. Good post on that here.

 

I did replace the TPS when I first got the Cherokee because of its idling issues and i did clean a whole lot of carbon off the IAC though that could be it as well. Map sensor seems to work normally. And i think I've fixed all possibly vacuum leaks. Thanks for linking the post!