Okay I know this has been asked before but here goes.
I replaced my 2nd O2 sensor on my motor and a week later it starts to hesitate again and bog down. I installed a DC header and i had to bung weld the second O2 on the bottom next to the other one. Could this be my problem? I just disconnected one sensor and it runs better but i dont think i fixed the problem.
Any help. BTW no cel light either.

 

Which DC header is it 4-1 or 4-2-1?Where exactly on the header did you have the o2s welded? Are they neat the cat or are they closer to the head like OEM location? These are the things we need to know to help.

 

on the dc 421 u need both o2s on hte "2" part of the header
then it works fine

 

i welded it next to the cat on the header pipe. It is a 4-2-1 2 piece header.
I did not want to weld it on the top piece because of look but I think I should have.
Yes I do have both sensors welded on.


[Modified by b16a1civichb, 10:37 PM 12/5/2002]

 

i believe one should be up higher towards the head

 

buy a HONDATA and run closed loop to get rid of the 02 sensor all together. If you have a pr3 you can use a Hondata chip. Or maybe open loop gets rid of 02 I forgot, but don't forget primary 02 is set for one pair of cylinders and the other 02 for the other pair of cylinders. If wired together or incorrectly you will have problems with getting fuel. What is your fuel pressure at? I had mine set to 33psi ant put out 142 fwhp on stock motor. Hows your gas mileage?

 

i have almost the same problem. got a 4-1 dc header and dont know where exactly to put the 2nd bung for the 2nd O2, can i out it on the CAT? or should i just place it anywhere on the pipe?

 

because u have an unheated o2 sensor, it needs to be close to the exuast ports... basicly like your OEM exaust manafold.
The reason why your car doesnt run right, is because both o2's are running off the same cylinder pair.

since you have a 4-2-1 header, you should have just copied the OEM exuast manafold and get it welded tward the top.

 

Yeah I disconnected the secondary sensor and it runs strong now. But I dont know if I'm running rich.

 

so do we need 2 O2's? or can i just run one? if i run one can i connect the 2nd O2's wire into the first wire by splicing it? will that work fine? anyone??

 

??

 

Could you explain this "closed loop" and "open loop" stuff. You lost me.

 

If you purchase a Hondata system you have the option of using the o2 sensor or not using an 02 sensor. Just click disable 02/ run closd loop. The 02 sensor will then not be used. Then dyno tune part throttle because fuel economy will suffer, but the car will run perfect. Thats what I did. good luck.

 

stock pr3 and pw0 ecu needs 2 o2 sensors..
chipped they may need 1 or none

i would not suggest running no 02 sensor.. your computer will never compensate for rich and lean and you'll get horrible gas mileage.. basically have an electronic carburetor.

 

Each O2 sensor is measuring it's own pair of cylinders, you need to run one reading 2 idividual cylinders and the other reading the other 2 cylinders. may sound weird but it actually runs better bause if a sensor reads rich or lean reading it can narrow it down to 2 cylinders rather then making adjustments to all 4 cylinders.

 

while running a hondata set up ona pr3, if i were to use the closed loop? no o2 sensor option, is that going to reslut in any power loss/gain ... or gas milage loss/gain ... i dont really unserstand the closed /open loop operations..

 

all you need to do is unplug both O2 sensors, I have had mine unplugged for over a year now and no problems

 

will replacing the stock o2 sensors get rid of sluggish performance?