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Discussion Starter #1
I was just wondering if anyone had ever figured out how NOT to get a CEL when headers are installed. I know this was kicked around alot on the old site and just wanted to know if anyone had come up with something on this other than unplug the light
 

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you need to get an o2 sensor simulator so the ecu thinks that the air is getting "cleaned" by the cats.

shawn :)
 

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A header with the first o2 sensor and then a high-flow cat and then the second o2 sensor should do the job. You need both o2 sensors or a simulator instead of the second. You just have to make sure that the high-flow cat has a high enough cell count.
 

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Super Hero
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no one who has a complete header-back system avoided a cel. there is a sim www.o2simulator.com/ that i will be trying. Hopefully I will order it today.

Fordfasterer tried a sim but couldn't get it to work porperly.

The other option which i have ranted about about a 100 times is this:

measure the distance from the core of the oem cat to the center point of the o2 sensor on the stock set up. I think it is about 14.5 inches. When you put in the new system, make sure the distance from the new cat and the repositioned o2 sensor is exactly the same. this "should" prevent the cel. I haven't tried it and no one else has yet either. I just lazy and kinda like looking at the little orange engine on my dash. :rolleyes:
 

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I do not get CELS. Full header and Cat Back exhaust. 2nd O2 sensor relocated to behind 2nd cat. First o2 in the header. Alex(Geraldelroy) does not have a cel anymore either. I lengthened his o2 sensor as well. I used cat5 cable wiring when creating the extensions, it is know to be very good wiring. Maybe this is why some people who have tried to extend the sensor have gotten a CEL, cheap wiring.
 

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I have have been getting CELs about every two or three weeks with my system. I have ghetto o2 sim (resistors soldered into the wiring) The code that usually comes up is slow response from 2nd sensor.
 

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evil, you used two cats after the header?
 

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XDGT03 said:
measure the distance from the core of the oem cat to the center point of the o2 sensor on the stock set up. I think it is about 14.5 inches. When you put in the new system, make sure the distance from the new cat and the repositioned o2 sensor is exactly the same. this "should" prevent the cel. I
Why would the distance matter? Shouldn't the exhaust gas composition be the same regardless of the distance from the cat? I can't imagine that the gas temp would be an issue, either.
 

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watson80 said:
or relocate ur 02 sensor
thats what I did and no cel
 

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Discussion Starter #13
What ever happened to the good old days of just taking off the manifold and bolting on a header with out all the BS.
I wanna get the OBX off ebay, but I just dont want to go through all this hassle with rewiring 02 sensors and CEL's. Are all the new cars like this now, or is Hyundai just the lucky one??
 

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Discussion Starter #15
I was wondering if all those guys that did that group buy from HP.com awhile back for those SS Autochrome headers liked tham, or if they were CEL 'd to death.
 

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Super Hero
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Why would the distance matter?
I talked with an exhaust guy who went to some training where they said moving the o2 sensor as little as 1/4 inch can cause a cel.

Shouldn't the exhaust gas composition be the same regardless of the distance from the cat?
Maybe as the gas cools, it changes in compsotion. (just talking out my ass on this one)

I can't imagine that the gas temp would be an issue, either.
Ours are heated. However, too close to the cat may cause it to "overheat" and give false readings because of it, or the above statement.

evil, how far is you o2 from your cat?

O_GT, what kinda wiring did you use and how far away is the o2 from the cat and did you use the oem second cat or aftermarket?
 

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I spliced and soldered the the harness side and used bigger gauge wire as not to cause more resistance.Do NOT SPLICE the sensor side this will damage it.Make the wires as short a possible this will keep resistance down.I used my OEM cat and as far as the distance Ill measure it at work to see what it is
 

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I'm thinking the oem cat must have something to do with not getting a cel.

I used some automotive wiring that was large gauge by a bit. It is wire that the mechanic shop buys in bulk. Not the most expensive, but not cheap ass stuff either. I spliced on the harness side. My sensor is about 8 inches from the aftermarket cat.
 

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O_GT said:
I spliced and soldered the the harness side and used bigger gauge wire as not to cause more resistance.Do NOT SPLICE the sensor side this will damage it.
I am a little confused by this maybe I am just reading it wrong. By sensor side are you referring to the actual o2 sensor that you can disconnect. When disconnected it is about 7-8 inches in length? If so that is what I cut, extended and soldered, on 3 cars now with no problems whatsoever. Maybe if you can post a pic or schematic from HMA.

XDGT03 said:
evil, how far is you o2 from your cat?
I'll try and check today
 
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