Headers and o2 sensors

[snapfrank]

headers that i want to fit on my 986 2001 all 02 are on the manifold

[Orient Red]

On each bank, one of the O2 sensors is supposed to be upstream of the catalytic converter, and one is supposed to be downstream. Many people who put aftermarket headers end up putting the downstream O2 in a new "bung" which is welded into the rear of the catalytic converter (this also requires lengthening the O2 sensor wires. If neither the headers or catalytic converter pipes has an upstream O2 sensor bung, then that will need to be added as well (either to the collector of the header or the first section of catalytic converter pipe).

[snapfrank]

Where should they go ( Remove Manifold) replace with headers

part 26 and 27 we move The o2 sensors


986 2001

[Orient Red]

Where you see the other O2 sensors (item 25, although they only show two in your picture, there are 4, one before each catalytic converter, and one after). Unfortunately, at least on my '01S, they eliminated the O2 sensor mounting points ("bungs", which are essentially threaded holes), so I had to have a muffler shop weld some on...

[Daniel R]

Just a thought, and I welcome anyone who knows more about this sort of thing to correct me, but there may be a way to delete 2 of the oxygen sensors.

Here in Australia, our cars are delivered new with only 1 oxygen sensor per bank, as we do not have 2 sets of cats (the ones on the headers are not there).

Would it be possible to reflash the car computer with the "Australian version" which is programmed only to process readings from one set of sensors and hence no CEL?

What do you guys think?

[snapfrank]

this is what i got from a local shop as of where they should go. place on headers with bungs. how to exstend the o2 wire now.

[JFP in PA]

Originally Posted by Daniel R

Just a thought, and I welcome anyone who knows more about this sort of thing to correct me, but there may be a way to delete 2 of the oxygen sensors.

Here in Australia, our cars are delivered new with only 1 oxygen sensor per bank, as we do not have 2 sets of cats (the ones on the headers are not there).

Would it be possible to reflash the car computer with the "Australian version" which is programmed only to process readings from one set of sensors and hence no CEL?

What do you guys think?

You are actually on to the correct solution. Only the US cars run four O2 sensors; if you install headers without the second set of O2 sensor bungs, you need to have a PST II/PIWIS reflash your DME to the RoW (Rest of World) profile, and the system will be happy with only two sensors..............

[root_werks]

Before we have him start drilling holes in those headers and having bungs welded in, look closely at the 3-bolt flanges. Do those look rounded to you? They kinda do to me.

I believe those are 2.5 headers and will NOT bolt up to your secondary cat-pipes. The flanges are DIFFERENT.

I could be wrong, but double check it. Take a striaght on picture of your collector flange, post it here. Those may not work on your Boxster.

-Dan