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I am planning on buying and installing a cut out valve for my exhaust, im not to sure were i should put it before or after my 02 sensor. Will my check engine light come on or run rough or what. thanks for your help.
 

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i would put it after your O2 sensor because then your sensor still gets the readings it needs and the engine will still run good and gain all the HP from the cutout, just my two cents
-Josh
 

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actually, it should be the other way around...if you put it after the cut-out and you open it up, the exhaust will exit out of the cut-out and the O2 sensor will pick up a different value and trip your check engine light. if you put it before, the O2 sensor will register the same output of exhaust gases because there is no interuption in exhaust flow...
 

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If you put it before the O2 sensor, wouldn't there still be a change in exhaust gas pressure, and the O2 sensor would pick it up? Seems like either way it will pick it up somehow.
Where do you get a cutout valve? Just take it to a shop and have them fab one up for you?

Nick.
 

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if you put it after your o2 sensor i doubt that your check engine light will come on. i've seen those cutouts in jc whitney before there pretty cool
 

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Summit racing sells them as well. Just remember that you wont be able to pass an emmissions inspection after you install a cutout.
 

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Yeah those cutouts are pretty sweet. If you place it before the O2 sensor, very little emissions would be traveling through it. However, depending on your setup, the O2 sensor is sometimes placed directly in the header pipe. Always place the cutout after your O2 sensor. The backpressure will change and the O2 sensor will still be able to pick up the differences. Placing the cutout in front will throw off the computer.
 

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On 2002-03-19 23:03, TUNIS wrote:
actually, it should be the other way around...if you put it after the cut-out and you open it up, the exhaust will exit out of the cut-out and the O2 sensor will pick up a different value and trip your check engine light. if you put it before, the O2 sensor will register the same output of exhaust gases because there is no interuption in exhaust flow...

if you put it before the sensor, no exhaust gas is going to pass by the sensor, inturn the sensor will tell the pcm the motor is running lean and dump more fuel into it and/or trigger the MIL.
 
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