dc sports header = error code

[rb25crazy]

hey

anyone else using the dc sports header for their s14 240sx as well? after, i installed the headers and high flow cat i'm getting an error code P0420 looks like some kind of catalyst problem error code. doesn't look like anything big, but i was wondering if anyone else hit this problem and what their solution was. quite possibly i have a leak somewhere on the exhaust before the sensors. but, it really doesn't seem to look that way. but i'll recheck again maybe take the headers off and clean the exhaust port edges again to make sure it's an 100% flat seal. i'm using mr. gasket exhaust gasket as well.

thanks for any help.

[murda-c]

don't remember what that code means, but is your second 02 sensor after the cat?

[rb25crazy]

on the stock exhaust manifold the cat was inbetween the two o2 sensors. now, my two o2 sensors are before the cat since it's at the rear. so, maybe that's why it's throwing a code? because i really don't think it's a leak since i don't feel anything coming out of the exhaust or feel any air or crazy fire or anything of that nature.

o2 o2 cat = dc sports header
o2 cat o2 = stock

so, that could be why? since the fsm says the 3 way catalyst function is not working or something. it's running hottter then it should be or so is what i'm getting at.

is the catalyic converter supposed to cool down the exhaust gases as well? and break down elements to make the exhaust cleaner? or just breaking down of gases to make the air cleaner.

thanks

[projectRDM]

Think about it for a second. The secondary O2 sensor sits behind the catalytic converter, monitoring emissions output. If they're both upstream the ECU will get the exact same reading from both which trips the CEL. The ECU thinks the cat is not working properly, which in fact it is you're just measuring ahead of it so the readings aren't changing.

So do like everyone else has done for the past thirteen years, plug the secondary port and weld a bung in the rear side of the cat. That way it reads the signal after the emissions levels are reduced.

You could have easily found that anywhere online, even Sport Compact Car did a writeup when they first tested a Hotshot header ages ago.

[rb25crazy]

haha, thanks a lot for the info. i never knew that so yeah i fail at life. but, appreciate the lesson none the less.

so get a hole after the cat and weld it up. so it'll appear to be working like stock again.

i actually did think of doing this already, but i wasn't sure if it'd work so i didn't want to go around messing around with it and just screwing it up some more.

now that it's confirmed =D time to go to a muffler shop and have them help me out.

one more thing though. so should i weld the bung on the cat back exhaust pipe? or around the "out" end tip of the catalyic converter. i was thinking that if i weld it at the end tip of the catlytic converter it'd be to close or soemthing, but then it shoulnd't really matter since it'll be at the end since that's where it leaves and goes into the catback exhaust and nothing else would change.

thanks just want to make 100% sure =D appreciate it again.

[projectRDM]

I'd do it in the cat, there's plenty of room past the material to drill a hole and weld a bung. It's also easier to weld to a flat surface than a curved one, the cat will have somewhat of a flat place before the rear flange. You'll also find the harness will be tight going back that far so any further and you'll have to cut/extend if you go into the exhaust.

FYI, Random Technologies sells a high flow unit for the 240SX that comes with the bung prefitted. You have to ask for it but they can do it without issue.

[alkemyst]

easier way is to just use spark plug non-foulers. Search for o2 fouler on google.

If you just weld the 2nd o2 hole you will still get a code.

[LA_phantom_240]

Strange, I don't get a second code with my s14 (OBDI).