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Oxygen sensor placement behind cats

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Old Sep 30, 2010 | 07:30 PM
  #1  
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Default Oxygen sensor placement behind cats

I'm setting up my lt/cat/true dual setup, and am a little concerned about my drivers side rear o2 sensor.

Here's what I'm dealing with:



My first instinct is to put the bung right behind the cat, where the pipe it still straight.... but is that too close to the cat?

And if I decide to put the sensor aft of the bend, how far after the elbow will I need to go so that I'm not getting a bad reading from the exhaust flow obstruction on the turn?

Appreciate any help here; I'm not used to setting up exhaust systems with cats
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Old Sep 30, 2010 | 07:52 PM
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delete them
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Old Sep 30, 2010 | 08:26 PM
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I think you are right putting them right after the CATS.
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Old Oct 1, 2010 | 09:26 AM
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Not all bitching deserves to be listened to. The rears
are there to do a monitoring job by decree. There is
no other use for them. You can put them in, but likely
no amount of "engineering" will make up for the fact
that they're gonna just be too cold to be reliable and
you'll still see the codes. So fix the codes.
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Old Oct 1, 2010 | 12:14 PM
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Why would there be codes?
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Old Oct 1, 2010 | 12:36 PM
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Originally Posted by FoxNotch
Why would there be codes?
Low catalyst efficiency, I believe.

Any particular reason you want to run rear O2s?
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Old Oct 1, 2010 | 12:56 PM
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Originally Posted by Element
Low catalyst efficiency, I believe.

Any particular reason you want to run rear O2s?
No reason in particular, I thought running cats with rear o2's was the way to avoid check engine lights. Am I way off here?
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Old Oct 1, 2010 | 01:13 PM
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You won't get rear-O2-related codes if they are full
time happy. But they won't be, or not for long. The
bigger, longer, higher-surface-area tube will not stay
hot enough. And just wait until winter.
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