02 sensor before cat

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Nov 12, 2005 | 01:02 PM

4.9inline6

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02 sensor before cat

today i hopped under my truck kinda checking out my exhaust options. my stepdad had the exhaust re-done years ago when it rusted out. it is a 93 f250 i6. it did have two cats. when the guy redid the exhaust, he removed one cat, leaving the other. what surprised me is there is an o2 sensor before that cat and none after. the o2 is actually mounted between the Y where the two exhaust pipes come together. next is the cat followed by the muffler. is this the normal setup or did mr. exhaust man do some crazy setup. if it is not the normal setup, does it sound like it could work?
chris

Nov 12, 2005 | 02:28 PM

Kista20

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From: Harrisonburg, VA

everything is just fine, pre-96 is obd1 so you only have one o2 sensor and it is before the first cat and also there is nothing wrong with just having one cat either.

Nov 12, 2005 | 02:40 PM

4.9inline6

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alrighty i was just checkin it out. ya i know that one cat is fine. in fact, i plan to pop a high flow on there...

Nov 12, 2005 | 02:52 PM

Motorhead351

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Anything done past the O2 sensor, on your speed density equipped engine and the eec has no idea whats happening, in your case both converters could be deleted, not saying to do it, just that its possible.

Nov 13, 2005 | 08:30 AM

4.9inline6

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i am considering it but i for one don't really like the idea of all the pollution and also i don't really want it to crackle as much as it would with it off.

Nov 13, 2005 | 10:29 AM

CMOS

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From: Magnolia, TX

Quote:

Originally Posted by Motorhead351

Anything done past the O2 sensor, on your speed density equipped engine and the eec has no idea whats happening, in your case both converters could be deleted

I was wondering about this. Doesn't exhaust "backpressure" have an effect on EGR function, etc. when switching to a high flow CAT and muffler (with an EFI engine)?

Thanks,
CMOS