89 4.0 o2 ?
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Joined: Oct 2011
Posts: 4,440
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From: Seal Beach, CA
Year: 1996
Model: Cherokee
Engine: 4.0 HO Straight Six
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.
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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CF Veteran
Joined: Nov 2011
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From: phoenix az
Year: 1989
Model: Cherokee
Engine: 4.0l 6 cylinder
Originally Posted by cruiser54
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.
Thread Starter
Member
Joined: Jan 2012
Posts: 113
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From: Centeral Valley CA
Year: 1987
Model: Cherokee
Engine: 4.0
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....
CF Veteran
Joined: Oct 2011
Posts: 1,268
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From: Bakersfield CA
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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.
Thread Starter
Member
Joined: Jan 2012
Posts: 113
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From: Centeral Valley CA
Year: 1987
Model: Cherokee
Engine: 4.0
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?
Thread Starter
Member
Joined: Jan 2012
Posts: 113
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From: Centeral Valley CA
Year: 1987
Model: Cherokee
Engine: 4.0
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....
CF Veteran
Joined: Oct 2011
Posts: 1,268
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From: Bakersfield CA
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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.
Thread Starter
Member
Joined: Jan 2012
Posts: 113
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From: Centeral Valley CA
Year: 1987
Model: Cherokee
Engine: 4.0
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.


