CAT converter
CAT converter
Hotshot
Joined: Sep 2001
Posts: 11,958
Likes: 228
Why do you need to bypass the O2 sensor? You should be able to do what you want with out removing that. If you don't have that sensor your truck will never run right. You can put pipes from the cat to the rear without having mufflers. Unless your truck is a 96 or newer OBDII, you should only have one 02 sensor. You could run straights from just behind it. That should work alright. You still may have issues with the air tube though. I have heard of people doing this and just leaving the tube hanging not connected to anything and not having any problems. Whatever you do with your exhaust do not remove the O2 sensor. It is related to performance and emmissions, not just emmissions.
Lead Driver
Joined: Feb 2003
Posts: 8,140
Likes: 4
From: Oak Harbor, OH
If you want it to be louder go buy a high flow dual in dual out cat, and run true duals. If you remove the cat it will cause odd readings from the o2 sensors and make the computer run in fail safe mode, which will make your gas mileage drop to about 5mpg.
Posting Guru
Joined: Jan 2004
Posts: 1,232
Likes: 0
Removing the cat on an OBDI truck will not affect the O2 sensor in anyway, the sensor is upstream of the cat and therefore would never know it was gone, OBII you would have issues with the second sensor picking up the change in gases.
Lead Driver
Joined: Feb 2003
Posts: 8,140
Likes: 4
From: Oak Harbor, OH
Wicky, I beg to differ.... It WILL indeed effect the o2 sensor. It's location is RIGHT before the cat in a 1/2 pipe connecting the two pipes of the y-pipe. WIthout the cat that pipe doesn't get enough exhaust flow to properly heat the o2 sensor, or for it to accurately read the a/f mixture. The light may or may not come on depending on the rest of the system...
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Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
Removing the cat will have no effect on O2 sensor performance. The same exhaust flows through the same pipes as always, so the O2 sensor will see the same thing and send the same information to the computer. I'm not advocating removal of the cat, but if it was removed, it would not affect O2 sensor output.
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Posting Guru
Joined: Jan 2004
Posts: 1,232
Likes: 0
EPNCSU is correct, same exhaust through same pipe, in the same amount. I am not saynig to remove it either. Also if it is an OBDI O2 sensor it is a 4 wire, HEATED, sensor therefore it doesn't rely on the cat to heat it.