Non-Fouler Question

[Deleted58156]

Hey guys,

I was wondering, when doing the non-fouler trick does it only apply to the first o2 sensor before the pre-cat or does it apply to the secondary after the pre-cat as well.

What i mean to say is, if i opt for an aftermarket header (probably obx) or the 4-2-1 setup that Rouge is selling, will i need to apply the non-fouler to both sensors or just the first one.

Thanks(2thumbs)

 

[bazooka joe]

just the second

 

[808MP5]

I thought it was the second one lol. Now I bet he's confused

 

[bazooka joe]

you're correct...(my bad)(iagree)

 

[Deleted58156]

so i would need to do the non fouler mod, to the second o2 sensor in line....not the o2 sensor directly about the pre cat?

 

[808MP5]

It's the second one

 

[Deleted58156]

sweet thank you good sir!!!

 

[slavrenz]

The point of the nonfouler is to move the O2 sensor out of the exhaust stream so that it thinks your cat is still there and is cleaning your exhaust (otherwise it would throw a CEL). If you did this to your front O2 sensor, which controls your air/fuel ratio, your car would run like crap!

 

[Deleted58156]

The point of the nonfouler is to move the O2 sensor out of the exhaust stream so that it thinks your cat is still there and is cleaning your exhaust (otherwise it would throw a CEL). If you did this to your front O2 sensor, which controls your air/fuel ratio, your car would run like crap!

correct but if i'm not mistaken you would have to do it anyways to the front o2 sensor if you were to put a header in anyways? Does the new header not compensate for the pre-cat? As after reading on here it has happened to most of the guys here, they change their exhaust manifold to a new header and then the cpu throws a an o2 CEL on. Unless of course you were to go in and retune your air/fuel mixture then i guess you wouldn't have to worry so much?

 

[thecrash91]

thats why you put the non fouler on the second bung, since the sensor is not actually in the exhaust pipe now, it takes in a lot less o2 thus making it think the cat converter is still there

 

[i12drivemyMP5]

correct but if i'm not mistaken you would have to do it anyways to the front o2 sensor if you were to put a header in anyways? Does the new header not compensate for the pre-cat? As after reading on here it has happened to most of the guys here, they change their exhaust manifold to a new header and then the cpu throws a an o2 CEL on. Unless of course you were to go in and retune your air/fuel mixture then i guess you wouldn't have to worry so much?

Reread the post you qouted above that states the first o2 sensor sets the a/f ratio & it wouldn't be able to do that if you non-fouler'd it & believe it. If you go with header, leave the first o2 as is & do non-fouler on the 2nd one...end of CEL, end of story. No need to complicate it any further unless you add a 3rd bung farther back for a wbo2 sensor to run actual a/f ratio gauge & feed a piggyback ecu or standalone to tune the fuel mapping.

 

[Deleted58156]

Reread the post you qouted above that states the first o2 sensor sets the a/f ratio & it wouldn't be able to do that if you non-fouler'd it & believe it. If you go with header, leave the first o2 as is & do non-fouler on the 2nd one...end of CEL, end of story. No need to complicate it any further unless you add a 3rd bung farther back for a wbo2 sensor to run actual a/f ratio gauge & feed a piggyback ecu or standalone to tune the fuel mapping.

I did actually read the response, it was fairly evident that i was replying to the statement posted about the non-fouler technique and not which bung it should be applied to. My question of where it should be applied was already answered.

 

[slavrenz]

I did actually read the response, it was fairly evident that i was replying to the statement posted about the non-fouler technique and not which bung it should be applied to. My question of where it should be applied was already answered.

Ok...not sure I quite understood your statement, but essentially the nonfouler is used to trick the car into thinking the cat is still there. Since the rear O2 sensor only monitors the performance of the cat (by comparing the exhaust after the cat with the stuff that went in), this is the one you need to "trick"

 

[MSM37]

spark plug extender on the second o2 sensor = done.

 

[i12drivemyMP5]

I did actually read the response, it was fairly evident that i was replying to the statement posted about the non-fouler technique and not which bung it should be applied to. My question of where it should be applied was already answered.

Nothing was evident that you understood to just leave the first sensor alone & nonfouler the 2nd sensor and be done when you are still asking questions about doing something to the 1st sensor. (see post #9 above) There are no questions above addressing which nonfouler to drill or which order to stack them which would refer to "technique". I do agree that your initial question had been answered multiple times.