I have CEL on and it's about ctaylic below threshold. I looked at the helms and says either cat is not good anymore or having a exhaust leak. I have new exhaust system and manifold. Before that happened, previously, i had CEL on for O2 sensor is bad so I replaced one of the O2 sensors (primary).

Should i try first to change the secondary O2 sensor even the manual did not say anything about it? Or just go ahead change the cat converter?

My last question is if I buya straight pipe cat converter would it work or would get worse since i have OBDII?

99 honda prelude SH

 

the secondary O2 sensor is used to measure how effectively the cat is working in an OD2 system, if the cat is barely working and your throwing a CEL for it taking the cat out completely probably wouldn't solve the problem

if you use a straight pipe you will need to get an 02 simulator to fool the computer and clear the CEL

 

is that O2 simulator is an add on part? where do you get that. I don't wanna buy a real cat converter cuz they are expensive.

 

you can get a direct bolt on magnaflow for 100 bucks

 

there are 2 types, a mechancal and an electrical.

the electrical just mimics the stock O2 sensor voltage and intercepts the signal back to the ECU with the correct voltage and there for tricks the ECU into think the cat is fine, ECU thinks the cat is doing it's job and no CEL.

a mechanical is just a small tube that you stick between the O2 sensor and the exhaust basically it only allows a small amount of exhaust gas to reach the sensor, this reads as the cat working because it does not detect as much of the pollutants and there the ECU is happy

you can get a mechanical 02 for like 2 bucks. it just looks like a small tube with a male and female threaded ends thats an 02 sensor would fit in.

 

Sound like the mechanical technique is lot easier but where do you get that? for the electrical part are you just short the vaoltage back to ECU?

I was wondering though some cars iv'e seen (not only hondas) they installed straight pipe cat with out doing some tricks to it. My friend he installed one on his probe GT and he got OBD 1 since his car is below 96 year, he should still get a CEL right?

 

The suggested mechanical device is actually a simple anti-fouler with the center cavity enlarged to fit the tip of the O2 sensor. You can get them at just about any auto parts stores.

 

DO YOU KNOW WHAT IS THE OFFICIAL NAME OF IT? IS THAT UNIVERSAL? U THINK NAPA HAS ONE?

DOES STAIRGHT PIPE WOULD CAUSE BLACK SMOKE WHEN INSTALLED?

I WAS ALSO WONDERING IF YOU LOOK AT THE O2 SENSOR THERE ARE SOME HOLES IN THERE, WOULD IT WORK IF YOU WELD/COVER THOSE HOLES AND LEAVE JUST FEW HOLES SO THAT THER IS ONLY SMALL AMOUNT OF GAS THAT O2 CAN DETECT OR SOMETHING..


Modified by zirac50 at 11:34 AM 4/21/2007

 

 

It's called anti-fouler or non-fouler depends on the packaging.

http://www.hostdub.com/albums/...d.jpg

 

thanks man appreciate your help..

 

for all that time and money buy the performance aftermarket cat converters. I got mine for 140 dollers and its bolt on. or for only 100 dollers for performance cat but you have to weld them on. better flow than stock but still keeps you legal. rudy held performance carries them, magna flow has a similar cat, just search. dont use test pipe/straight pipe if you have emmisson tests.

 

$140 cat converter bolt on plus $70 secondary O2 sensor (denso). these are all i need, so much cheaper 20 dollars test pipe from ebay bolt on. If I don't like it den i'll buy the legal one like you said. I wanna really know if there is a really big difference in straight pipe versus legal cat interms of power. If there is not much, den i'll switch back to legal.