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Go Back   Fun In B.C. > All about your Ride > Jeep Talk

Jeep Talk The only true 4x4

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Old 10-17-2013, 06:10 PM
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Bushwack Bushwack is offline
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downstream O2 sensor Question

Ok ......I have read all the internet bullshit on what the downstream O2 sensor does and still do not know if you really need it. Some say it only throws a code for the cat.. others it affects engine fuel mixture and timing.
Can anyone that really knows the facts let me know before I waist money on one. 97 Cherokee 4.0 (downstream)
The faulty one shorted out intermittently, causing the cat fuse to blow and the engine ran like a bag of shit. Traced it down to a small rock dent on the sensor. I removed the little bugger and replaced the fuse and it seems to purr like a kitten. I need to air scare the jeep before I can re insure it and want to know before I waist money. ..HELP!!
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Old 10-17-2013, 07:12 PM
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No engine codes should be good
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Old 10-17-2013, 08:20 PM
96_z71 96_z71 is offline
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My brothers 96 cherokee was intermitently running shitty shortly after I changed the pre-cat o2 sensor. It had thrown a soft code for downstream o2 sensor. I asked around and some people were saying that it does affect air fuel mixture, while others said because the primary was so new and secondary was so old that that could cause the rough running, didn't make sense to me but I changed the downstream sensor and the problem went away.

But ya I've always thought the primary was there to adjust air fuel while the secondary was there to verify the cats doing its job...
'96 Z71,350 with boltons, built 4l60e, 14 bolt, 6"+3" body, AAL, Posi-Lok, 37s
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Old 10-17-2013, 08:34 PM
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Happypants Happypants is offline
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Wouldn't it be a open or closed loop system if it has 2 o2 sensors? Mandy's explorer has 4 and if one is fucked it won't complete the circuit this make the check engine light come on and run like a bag of shit,
Originally Posted by pudge
try to keep up spongebob, you're sucking his dick, whilest Mrs Tuna jams herself and Jerm watches
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Old 10-20-2013, 11:55 AM
mus-Tard mus-Tard is offline
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the first o2 sensor should be the "o2 sensor" that measures fuel mixture.
the one down stream of the cat should be the "catalyst monitor" which like the name states, keeps an eye on the efficiency of the cat.

both should have the ability of causing the MIL to come on. the latter of the 2 having a code about 'catalyst efficiency'

l would replace it.
is it true that if you touch your eye to a brown eye, you get a pink eye?
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