Does the O2 in an 89 4.0 have any afect on overall function of the engine performance?

Yep, it determines the fuel/air ratio travelling through your exhaust pipe. If the o2 sensor is going bad, it'll dump more fuel in that it is supposed to, making you run richer and decreasing your mileage. Also, you can have a rough idle if your o2 goes bad.

They're only good for about 80K miles anyway.

I have an 89 Cherokee Laredo 4x4 straight six. Does the o2 sensor need to be one that heats, because mine does not. Does that make a difference on engine performance?
Thanks

Your Jeep needs an O2 sensor specific to it. You can't use a universal sensor. Napa has the right one for about $50.

My 89 is smelling alittle rich wen I have it running in the garage

Ever replaced the O2 sensor? Or tested it?

They don't have to be good or bad. They get lazy and react slower with age. Kinda like me.

Thinking about changing it but have other expenses right now

none of the above. I put a header for a 99 on my 89 and built the exhaust from scratch. Where we put the O2 was too close to the diff and got boken off the pipe. It seems to run just fine without it....

O2 sensor on a RENIX is a must have. The emissions control system on a RENIX is about as basic as you can get, and only has the one O2 sensor and needs it. Without it your gas mileage will suffer and most of your engine due to all the excess fuel getting thrown at it.

Ah Bako, the armpit of Cali. lol I can say that cuz im from Hanford. lol Got a homie from Oildale, with a 98 on 35s. Yea I understand on the Renix, but what does it do for the Pre-95s OBD1 system?

on that one you have a before and after ??? you can lose one and you should still be ok kinda. given the choice the back one

No I just have one. it dosent smoke or have any loss in power at all, It does sputter between 2000-2500 rmp at low to mid load acceleration. But I think ive tracked that down to the distributer. It like the injectors get outa time at that rpm....

could be loading up on fuel too, I'd do a walkthrough of the emissions system if the distributor doesn't pan out. or starving for fuel, filter maybe. not the O2 sensor to stay on topic.

Yea im on same page. Just wondering if its necesary to have an O2 for this system. With the header and lil bigger exhaust and tb spacer, makes a big difference.