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Old 08-23-2012, 11:06 PM   #1
Hbenmeir
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Cat converter

What happens on an 01 3.0 when you hollow out the cat to free up the flow of the exhaust. Do The o2 sensors gone on the fritz due to the cat bring hollowed out. Or will they be fine because the exhaust is still flowing.
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Old 08-23-2012, 11:41 PM   #2
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The O2 sensors will hate you and notice that the cats are no longer working and you'll have a lovely CEL on your dash. Is this not obvious? Why else do we have post-cat O2 sensors?
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Old 08-24-2012, 07:35 AM   #3
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Different on all cars just asking a question. Yeah it's obvious obvious that cat converter robs a good 10-20 horsepower cause there is no flow through the cat . Smart ass just a question

Last edited by Hbenmeir; 08-24-2012 at 07:54 AM.
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Old 08-24-2012, 07:52 AM   #4
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What happens on an 01 3.0 when you hollow out the cat to free up the flow of the exhaust. Do The o2 sensors gone on the fritz due to the cat bring hollowed out. Or will they be fine because the exhaust is still flowing.
If you are going to take the time to remove the headers, spend the $250 and get a pair of SS ones. Cat or no cat, the stock headers merger at what looks to be <1in diameter.

And I'm not sure what you meant by "exhaust is still flowing". Cars measure the percentage of oxygen in the stream, not the flow...
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Old 08-24-2012, 08:12 AM   #5
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I was gonna do a header. Anyone know anything About the m18 universal o2 simulator that screws on to the end of the o2 and plays simulator. I live in a place with no emissions so I wanna do what I can with the exhaust to free up flow, power, and have a little more grunt. And I have never seen so many sensors in the exhaust usually 1 maybe 2 if any At all so I find this weird.

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Old 08-24-2012, 08:14 AM   #6
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I was gonna do a header. Anyone know anything About the m18 universal o2 simulator that screws on to the end of the o2 and plays simulator. I live in a place with no emissions so I wanna do what I can with the exhaust to free up flow power and have a little more grunt. And I have never seen many sensors the exhaust usually 1 maybe 2 if any At all so I find this weird.
I think you can also flash EU2 software which ignores O2 sensors all together.
I wish I could do the same on the xi. the cats are not effective anymore which triggers the CEL every now and then.
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Old 08-24-2012, 08:21 AM   #7
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Oh yeah, where is a good place to find that software
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Old 08-24-2012, 08:23 AM   #8
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If you search innovative lc1 on this forum you will find a solution. Also, "hollowing out" your cats won't help too much because of the design of your exhaust manifold on the 3 series. You really need headers,and the best solution for emission compliance is to install high flow aftermarket cats like Racing Dynamics, or oem euro cats. Just leaving the check engine light on all the time will prevent you from being alerted to other problems your car may have.

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Old 08-24-2012, 08:26 AM   #9
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Oh yeah, where is a good place to find that software
its online. you can use a OBD2 cable and a laptop to flash it.
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Old 08-24-2012, 09:00 AM   #10
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The whole reason I brought this up is because the exhaust before I assume what is the silencer( small one right before the rear) is cracking I at the moment don't have enough for a full aftermarket. So can I pull that out and straight pipe that section and while doing that pull or gut the cat and put in sensor simulators till I can swing a header and exhaust.
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Old 08-24-2012, 09:02 AM   #11
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The whole reason I brought this up is because the exhaust before I assume what is the silencer( small one right before the rear) is cracking I at the moment don't have enough for a full aftermarket. So can I pull that out and straight pipe that section and while doing that pull or gut the cat and put in sensor simulators till I can swing a header and exhaust.
the cat is up the header.
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Old 08-24-2012, 09:04 AM   #12
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Well at 175k how good of an idea is it to put in a header. Should I just wait until I swap the engine for another 3.0 with less miles.
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Old 08-24-2012, 09:07 AM   #13
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Well at 175k how good of an idea is it to put in a header. Should I just wait until I swap the engine for another 3.0 with less miles.
I dont see why it would matter.
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Old 08-24-2012, 09:09 AM   #14
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I have figured that out at this point. That makes it difficult I suppose
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Old 08-24-2012, 09:09 AM   #15
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Pain in the ass.
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Old 08-24-2012, 09:11 AM   #16
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So header exhaust and software that will help me get rid of the pesky 4 o2 sensor problem
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Old 08-24-2012, 09:13 AM   #17
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How difficult is it to install a header with engine in the car. Mostly from under neath
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Old 09-10-2012, 01:13 AM   #18
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maybe need professional tool
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