so ive been doing a mini me swap with a friend for his 89 civic(swapped in a d16a6 putting a d16z6 gead on)

we were in the process of installing the header, and i was not able to get the old o2(4 wire) sensor from the stock d16z6 header. it preety much wleded in their so i told him(for my own reasons) ill go pick him up one.

he told me no once u put aftermarket headers on to an engien the o2 sensor becomes useless and does not do its job/work properly.

ive never heard anyone say this before let alone in all the mini swaps/ changing headers ive always replaced the o2 sensors with a new one OR used a bung to eliminate and then compensate from the ecu but even still.

i jsut want to double check from you guys that this is wrong or at least sounds wrong. i think o2 sensors will still work right where it afermarket header or not wheter it located on the header or right before the cat( if there is a cat)

 

There is a semi-problem with the one wire O2 sensor(Because of how long it takes to heat up)

But with a four wire it should work as designed.(Because the O2 sensor has a heater in it)

Hope that clears it up.

 

no i understand that part my friend is saying that no matter what kinda of o2 sensor i use its pointless to use with aftermarket headers. he says casue the headers are shaped diffrently and getting diffrent flow the casue the o2 sensor to not work correctly thus making it pointless to have one and have aftermakret headers elimates the fact of needing an o2 sensor.

this seems mighty wrong to me and ive trie to explain to him why its wrong but he thinks he is right and does not want me to install an o2 sensor on to his mini me swap

 

Your friend is wrong.
If the O2 can heat up properly is the main concern which you already understand.

Exhaust gases are still going to be present inside the manifold and the O2 will still read them.
If this were NOT true then everyone that bought a header would instantly throw an O2 code.

 

ya that exactly wjat i was trying to tell him ill show him this thred and let him read it and he will see its not just me thinking/saying that

thnx for the post 4drEF