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Unread 05-04-2012, 04:43 PM   #1
raceman77
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1993 YJ Wrangler 
 
Join Date: Mar 2010
Location: Baltimore,MD
Posts: 8
just bought a 93 yj Sahara, no O2 sensor,sputters

This is my 4th jeep and not my first rodeo the jeep does have an aftermarket header on it. l cannot,for the life of me,find the O2 sensor. l searched the cat and unless l have to take off the underbody protective plate covering the cat,,,l can`t find a trace of it. The big problem is under hard acceleration the engine hesitates,sputters,goes flat and throws a check engine light. The light goes off once l`ve cycled the ignition on/off and the jeep runs fine at low throttle openings. l can rev it in neutral with no codes also. Any help with this would be greatly appreciated

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Unread 05-04-2012, 06:07 PM   #2
pete1991YJ
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1991 YJ Wrangler 
 
Join Date: Mar 2012
Location: Niagara Falls, NY
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There should be a bung for the O2 sensor in the head pipe before the cat. Also there is definitely an error code stored in the computer. Might want to use the key trick to retrieve it. BTW welcome to JF, you've just found one of the best jeep sites anywhere!

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Unread 05-04-2012, 06:18 PM   #3
raceman77
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1993 YJ Wrangler 
 
Join Date: Mar 2010
Location: Baltimore,MD
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thanks very much for the response.l`m just thinking that whoever ( PO ) installed the header they did away with the O2 sensor and the FI system has been running "open loop" since then... l really can`t find an O2 bung or sensor anywhere...
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Unread 05-04-2012, 06:56 PM   #4
DRLongo
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1992 YJ Wrangler 
 
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Location: Pittsgrove, Nj
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On a '91 there is only one o2 sensor and the boss for it should be about 6inches downstream of the header flange
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Unread 05-04-2012, 07:27 PM   #5
pete1991YJ
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Quote:
Originally Posted by raceman77 View Post
thanks very much for the response.l`m just thinking that whoever ( PO ) installed the header they did away with the O2 sensor and the FI system has been running "open loop" since then... l really can`t find an O2 bung or sensor anywhere...
You're probably right - the computer will let you know for sure. I would try to find the plug on the wire harness and have a bung welded in. Most exhaust shops will do it pretty cheap, less than $40. Dunno why somebody would leave it out, when they run so much better with it.

If you can't find the plug, there are more than a few wiring experts around here. I have some of the diagrams from them. As far as which pin on the computer it supposed to plug into, etc.
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Unread 05-05-2012, 07:47 AM   #6
raceman77
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1993 YJ Wrangler 
 
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thanks guys, yeah any help is greatly appreciated.l`m going to be working on it today, heading out to the auto salvage to get some parts and all that. Does anyone know where the O2 pigtail should be?
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Unread 05-05-2012, 09:32 AM   #7
OKwranglerYJ
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1995 YJ Wrangler 
 
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Here's some pictures for you.
image-3769766799.jpg   image-2409259763.jpg   image-2321186635.jpg   image-989247920.jpg  
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Unread 05-05-2012, 11:02 AM   #8
raceman77
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1993 YJ Wrangler 
 
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Location: Baltimore,MD
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awesome pics,thanks a lot. l just went to local auto salvage and got TPS , MAP and IAT sensors and a couple odds and ends but l should probably sort the O2 situation first before parts swapping...l`ll post my findings
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Unread 04-30-2013, 11:40 PM   #9
scottieboy
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1991 YJ Wrangler 
 
Join Date: Jun 2008
Location: Chicago, IL
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I have this identical issue, by any chance did installing the o2 help? Was there maybe a bad cat because of the rich fuel ratio?
Or was it something else?
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