Headers & C02 Sensors?

[Rowie]

Ive been meaning to shoot off this question off for a while since I installed my headers.

They are 4-2-1 headers and there is what I think is called a C02 sensor that connects to one of the headers sections.

This is what it looks like at the moment (please excuse the dodgy illistration):

http://www.coresupreme.com/gallery/albums/userpics/q01.jpg

I was curious why this sensor is only on one section and shouldnt it look like this??? :

http://www.coresupreme.com/gallery/albums/userpics/q02.jpg


Can anyone shed some light on this for me??? Thanks.

[LatinoHatchCrap]

It would usually be sitting just before the flange which connects to the CAT. some d-series have tow of em. One in 4 secition and another one in the 1 secition. Its just a design issue; Honda engineers found that the optimal spot for it was before the flange 'cose all the latter b-series motors (b16a2, b18c1/2/5/7) have it there. :)

[Rowie]

what exactly does this sensor do, and is it called a C02 sensor?

[A'PEXi]

guess - lets the ecu know the exhaust temp? :P

[UR2L8]

No, the o2 sensor is the last line of burning any extra fuel left over. I know the TYpeR has 2 of them one which is on that second part of the 2-1 part of the header and the other somewere alse cant remember. When you start your car and it performs all those checks those lights pop up, it is the yellow engine light which makes sure everything is working well.

[stockie]

it basically is just a sensor that is hooked up to the computer to tell it how the mixers are in the exhaust. If the mixtures are rich, then the computer will adjust to fuel flow, and if the mixers are too lean then the computer will add fuel flow. This is best seen if you have a air/fuel ration gauge. You wouldnt believe how many times it changes from rich to lean, and from lean to rich. And they place it there because realistically, all the mixtures (no matter from which cylinder it is coming from) should be the same.

** please correct me if im wrong but im pretty sure that im right

[poid]

All the O2 sensor does is tell the ECU whether the mixture is rich, lean or stoich when in closed loop mode.

Closed loop mode on the ECU is normally when cruising, and the ECU uses the input from the O2 sensor to keep the air/fuel ratio running at a stoich 14.7:1. Thats all it does. When you step on it and there is a reasonable load on the engine then it goes into open loop and the ECU just reads its fuel and ignition maps to run the car without using the O2 sensor input.

Oh yeh, what it does is measure the amount of hydrocarbons passing through the exhaust that ocur when fuel is burnt, and it cant tell the ECU with any precision what the A/F ratio is. Just whether it is lean, stoich or rich and the ECU adjusts until the mixture is stoich in closed loop. Hence the air/fuel ratio gauges that you buy from autometer etc are nothing more than a light show, as you dont know how rich or lean the mixture is. Unless you have a wideband O2 sensor, which will tell you exactly what your A/F ratio is.

[tinkerbell]

so to answer the question - i need to know what sort of ECU you ar running...

if it is OBD0 it should be using two 'un-heated' o2 sensors near the exhaust ports...

if it is >OBD1 you should have one 'heated' o2 sensor near the last Y of the headers...

the second o2 sensor in the type Rs' and latter OBD2 cars is a catalytic converter sensor that 'checks' the readings after the cat and compares them to the first o2 sensor and determines whether hte cat is still operating properly...

[tinkerbell]

BTW - poid, it doesnt measure hydrocarbons, it measures Oxygen...

[poid]

yeh you're right, i got a couple of wires crossed in my brain with that one :P

[bizee_1]

1st Gen b16a has two O2 sensors aswell. I neglected to mention that to the exhaust fitter when he was ordering in my headers. Thinking it only had a single sensor. What a shock we had come installation day.

The above which i think tinkerbell covered already, although in terms of OBD0 & OBD1.