ShinotakuX

I recently made a purchase on a Apexi WS2 cat-back system, I just want to know if I should change the cat too, I dont know if its bad or not, but one of my friend said that if the cat is bad, then the o2 sensor is bad, is this correct? I'm not getting any CEL or hearing ratting sound. Also, is it necessary to change to a test pipe or some other cat? thank you.

crazyguy

u can change the cat to a test pipe but it will be loud but better air flow..but illegal...if your cat converter does not rattle..or make any noise..then it is ok
and ws2 is a good cat back i am actually thinking about getting one too

Probot

what year is your car...that makes a difference..older civics dont have the 2ndary rear o2 sensor...but to answer your question, if your cat is bad, you will lose alot of power and flow...best way to tell if its losing flow..start the car, hit the gas a couple times and feel the tail pipe real quick, there should be a good amount of pressure coming out - but yea, if your cat is really bad...youll actually hear exhaust come out of the cat..the springs stretch out almost as a fail safe so that exhaust doesnt go back into the motor...it sucks..but its a cheap easy fix


PS: dont use a test pipe..if anything at all get a high flow cat...but check your cat the way i said, if you have to replace it..get an oem cat..a high flow cat (and even a test pipe) doesn't give you much of anything except noise and smell. stick with an OEM cat

ShinotakuX

its a 96 honda civic ex aka ej8.

Probot

yea, you have the 2ndary sensor - just check for flow like i described, but most of the time, if your cat is going bad the sensor will throw a CEL

or if you are really worried about..just pick up a new oem replacement one from an auto parts store..they are cheap

crazyguy

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ShinotakuX &raquo;</TD></TR><TR><TD CLASS="quote">its a 96 honda civic ex aka ej8.</TD></TR></TABLE>
yeah ej or ek has secondary o2 sensor on the cat converter...and the aftermarket test pipe will have o2 bunk on it too..

thesmogman

Your car has a secondary O2 sensor after the cat(Or on it)

You should get a cel if the cat is bad. Or like your friend said you have a bad o2 sensor on or after the cat, it would throw a code still. The secondary O2 sensors only job is to keep an eye on the cat.

In CA you will have to do smog checks so a cat is required to pass I suggest an OEM one if you do need to replace it.

If no cel then you are ok and the cat is too.

hondamark35

yeah, if the cats bad you'll throw a p0420 i think. either way it's more often the cat bad not the O2 on these models. in my experience that is...

HondamanXxX

Are you guys sure a High Flow Cat will still pass inspection - NJ?

EDIT: How much of a sound differnece between the high flow and a test pipe. x10000 lol

Padawan

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HondamanXxX &raquo;</TD></TR><TR><TD CLASS="quote">Are you guys sure a High Flow Cat will still pass inspection - NJ? </TD></TR></TABLE>

It depends upon the cat.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HondamanXxX &raquo;</TD></TR><TR><TD CLASS="quote">EDIT: How much of a sound differnece between the high flow and a test pipe. x10000 lol</TD></TR></TABLE>

Most test pipes normally result in a "raspy" exhaust note, which is avoided when using a true high-flow cat.