99 xj 4.0 aw4. Rough idle. Sputters until you get in the throttle. It's saying o2 sensor upstream bad. I changed it and still sputters. Not wanting to throw tons of cash at it. It's my dd and weekend warrior. Any help would be appreciated.

 

can you tell us the code that it threw to lead you to believe it was an o2 sensor?

 

I don't remember exactly. But I replaced o2 and code went away. Now it still sputters.

 

Check your spark and fuel pressure I had a weak spark and bad pressure fall off and I stuttered with no code. To fix mine I replaced ignition coil and fuel pump.

 

Have the codes run again and post the exact numbers here. That way we have an idea on what we are working with.

 

Im gonna say its time for a tune up, wires, plugs, seafoam, remove and clean injectors if needed or upgrade the injectors to neons

 

It was Po132 and Po135. I have fixed them today however.

 

I would clean the TB and IAC, then do a regular tune up. Always start with the free-to-do stuff.

 

Did all that today. Codes are back. Guy at store thinks I got a bad o2 sensor so it's under warranty. And the PO put a CPS in it. And that's under warranty as well

 

Figured it out. O2 sensor harness wires rubbed along manifold.

 

Good to hear. glad to see you got it fixed. those wires by the manifold can be mean. gotta make sure they get secured out of the way.