hes not around here anymore.

heres the thing on that subject. if you do not have a cat inbetween the 2 o2 sensors you WILL get a cel. the first one should be reading exhaust gasses before passing through any cats, and the 2nd one should be reading gas after passing through a cat.

You should get a CEL if you do it that way, although there was one person on this forum that said they didn't get one. And you could cripple your car's performance, since the O2 sensor will only be reading 1/4 of the exhaust. Some here say the latter is not true, but that's what my mechanic said.

If your header has two O2 bungs, plug the one on the runner, put your primary sensor in the bung near the flexpipe, and have a bung installed after your cat for the second one.

The rest of the pics in the first post are still good. Is there any way to get around the vbb limitation so they can be viewed?

There's a lot of people saying our cars won't throw CEL's without cats because our emissions are so low. Bullsh*t for 85% of us i'd say. I put my rear O2 in front and got a bad reading from it. The only way I could get it off was to extend both of the sensors one before the cat and one after...

I think OP got away without a cat. My ECU is like a doberman watch dog... that thing snaps at everything!!

it makes no difference if they see all the exhaust gas or not, as long as they see a proper representation of what the true properties of the gas are. o2 sensors only read a ratio, which should be the same if youre on one runner or the entire "down" pipe. of course you could have a dirty injector or crap plug creating a different a/f ratio in one runner than what it is in the entire thing.

So theoreticaly you should be able to use the O2 bung in the single runner and plug the O2 bung at the flex pipe, and have the second O2 after the cat, and you shouldn't throw a CEL. Correct?

correct.

<div class='quotetop'>QUOTE (drafter @ Apr 29 2004, 04:24 PM) <{POST_SNAPBACK}></div><div class='quotemain'>You may want to put in there that people should wipe down the header after install to remove any oils left from their hands. These will show up as nasty looking spots/stains after the header is heated up and cooled a number of times.</div>
Yup.
I wish I would had known that beforehand.

Awesome DIY.

ok i kinda got confused confused.gif as far as i know there are two O2 sensors one before the cat and one after

help clear this up for me thanks

yeah, but our stock exhaust has 2 cats, on right after the header and one further down after the flex pipe. the stock location of the 02 sensors is right before the first cat and right before the 2nd one.

aftermarket headers eliminate the first cat, so there is no difference in what the 2 o2 sensors see, causing a cel.

that is weird for some reason my aftermarket header has the same amount of sensors as the stock but thanks for the help fing02.gif