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So i want to put a header on my car with no catylitic converter and then straight back to a muffler with no resonator(No strict emmissions control in my area, not worried about any inspection)but i don't want the engine light to be on, what do i do??? i have the ability to weld new sensor nuts on the headers if i have to put the 02 sensors back in but do i?? any ideas here (2003 civic coupe 1.7L)

 
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hey, check this out,https://www.civicforums.com/forums/7...simulator.html its what im in the process of, itll solve ur problem when u get ur header, btw, what motor do u have, a1 or a2, (vtec, or non-vtec)

 
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I have a v-tech motor, thanx i'll go check that out

 
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u do realize ur car is going to sound DISGUSTING, TERRIBLE, FRIGHTENING, NAUSEATING AND RICEY all at one time???

 
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Without any 02 sensing at all, the computer wont know what the hell is going on. When that happens, the car goes into limp mode.
Why on earth you'd straight pipe a 4 banger on anything but a full race car is beyond me. Get some serious ear protection, you're gonna need it.

 
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well if i put an aftermarket cat in it i should just have to put the second 02 sensor after the cat right????

 
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well what do you guys do then when u put a header on your cars??? where do you put the o2 sensors?

 
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I didn't say straight pipe did i ??? no i said there would be a muffler on there just no cat, and with no cat the engine light is on

 
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bro...thats not what we are talking about. u cant just have no 02 sensors regardless. u have to drill somewhere and drop in an 02 sensor. if it gets too bad of a reading or no reading..then u go into limp mode. but ur saying u want a straight pipe from your header to your muffler.. we realize that and that is a bad idea. u wont gain any power and its going to sound disgusting and super loud.

what i suggest to you.. if u dont want ur cat (dont know why), at least get a test pipe. that way the holes for ur 02 sensors are already drilled. then u get mechanical 02 sensor thing to take off the check engine light. then from the test pipe u can use a str8 pipe to ur "quality" muffler that u should get. on top of that...the sound will still be not that great at all. so between ur test pipe and muffler, throw in a universal resonator..and u will be happy with ur exhaust.

im curious as to why u would want a straight pipe from ur header to a muffler with no cat or anything in between in the first place...why??

 
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ok.......I am a welder and have welded up my own quality header with proper flow just like one you would buy.My car origonally had a exhaust manifold with the cat all in one piece, as u probably already know.So to put my header on the cat is no longer in the exhaust system.I have adapted two 02 sensor nuts(the first one is on the header, the second is on the downpipe)so they just screw right in like they normaly would.But being as there is no cat in the system, the engine light goes on because the second 02 sensor detects there is no cat.So what i'm getting at is how do i get around having the engine on????????or does there absolutly have to be a cat in the system for that light to go off??What i mean is what do all you guys do when u put a header on??? what do you put after that??a cat?Cause if i was to put an aftermarket cat on the downpipe, i would have to put the second 02 sensor after the cat right????So the computer knows that there is one there.Sorry for being confusing but i am frustrated with this problem and the car.......i am gonna post this on a different thread but if ur like me and own a 2001-03 with m/t you should get it checked out cause there is a recall on the gear box in case u didn't know, anyways thanx again and hope to see a reply.....oh yeah, mechanical 02 sensor thing??? whats that?