Headers and o2 sensors

[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

[root_werks]

97-99 flange gasket:
996-111-113-02
2000-up flange gasket:
996-113-113-00

Different and from what I have read, not interchangible.

[snapfrank]

what iv seen of the headers on my 2001 is that will bolt on i need two bungs as the pic in lower case. headers sold for my car with the 2 o2 sensors are at the same place that i have should in the pic. i will try it and let you know. now is it a 18-1.25 or 18-1.5 bungs i need 986 2001 us model.

[manolo]

Its M18x1.5 for the sensors.

[Lightning]

You can use one of those locations on the header to install the leading O2 sensors.

If you don't put the trailing O2 sensors behind the remaining catalytic converter, you WILL get a Check Engine Light (because the ECU checks to see a difference in O2 readings between the leading and trailing sensors) and it won't go away.

As far as re-flashing the ECU, it depends upon your country's emissions testing laws...

[snapfrank]

so do i move them like in the pics or back all of them 1 space