Topic: o2 sensor

[tasbm5]

Hi guys just wondering if i could get a little help here.The other day i was at the local jeep shop talking to the guy who owned the place. We were in the parking lot and  my jeep started to idle rough then smoothed out any how to me this was normal  but he said something about a o2 sensor exhaust ,bla,bla bla well thats what it sounded like in my little brain.So after some googleing there is 2 sensors 1 before the cat and one after so my question is there a way to tell the one causing the problem ? there is no check engine light on oh ya i have a 97 TJ 2.5 L .

                                                                                 thanks in advance terry..

[Jeffy]

First thing to do is check for CEL codes.  Even if the light doesn't turn on, there many be codes stored.

Does the engine sound like it's going to stall then races back up then settles?

[aw12345]

The one after the cat checks for cat converter efficiency has no effect on running of the engine

[tasbm5]

yes that's just what it does.

[tasbm5]

also just did a code check no codes came up .

[Jeffy]

The reving is caused when the PCM senses the stall and tries to compensate.  An O2 sensor would usually cause the light to come on though.  When mine was going out, it wouldn't only come on while driving for some reason.  I could tell the loss of power and then the light would come on.  It idled OK though.

I wonder if it's the CPS.

[tasbm5]

would there not be code errors if this was the problem also thanks for your help.