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Old 07-19-2010, 03:39 PM   #1
Tj Timmy's Avatar
Join Date: Jul 2010
Posts: 129
O2 sensor ?'s

I recently had the check engine light come on in my 05 wrangler sport, it says the engine is running lean. Its got an aftermarket banks monster exhaust system on it. Does anybody else have the system on their rig or heard of anyone with it on theirs having similar problems? should i just put O2 simulators in their place because this could get expensive if i have to replace these every couple of months. Any advice is appriciated. Thanks in advance


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Old 07-19-2010, 06:14 PM   #2
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changing exhaust might be causing jeep to actually be running lean. on YJ we just up the fuel rail presure to adjust. or put in bigger injectors. should check what your air/fuel ratio is and adjust as needed.

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Old 07-19-2010, 07:09 PM   #3
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You dont mention which code in particular but since you said its running lean im fairly confident its talking about one of the upstream O2 sensors. If thats the case you cannot put O2 simulators on those as those wouldnt tell the PCM correctly how to adjust the fuel. The upstream O2s are in the exhaust header and those should stay as is and correct the issue at hand.

O2 simulators are meant for downstream (after catalytic converters) only. Its for folks that run "offroad only" and dont have any cats.

I agree with flatline there a bit, need to first see whats going on, if you got access to a live scanner, would like to see what the o2s are reading and how they are switching back and forth. Lean represents its sitting more on the 0.7-0.9v side instead of around the .4-.5v side (which is where it should be for correct a/f ratio). But the live chart will show it switching up and down evenly. If it leans more on one side then thats where it determines if its running lean or rich.

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Old 07-19-2010, 08:31 PM   #4
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im sorry i did fail to mention which one it was. it is an upstream O2. a little bit more info on this, i went out this afternoon and started it and the light was off. What might that mean? if it was bad shouldnt it be on all the time?
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Old 07-19-2010, 10:21 PM   #5
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My CEL used to go on and off (off on start up and on with some rpm's).... After a free test from AutoZone to confirm a bad o2 sensor, a few bucks for a new one with a AutoZone free o2 removal wrench rental, and a busted knuckle I haven't seen the light since!
Nobody ever defended anything successfully, there is only attack and attack and attack some more.

George S. Patton
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