Removing catalytic converter from the exhaust?

Post by **unknow** » Mon Sep 07, 2009 4:22 pm

Hi,

I'm just wondering if I removed catalytic converter from the exhaust would I have a CEL on?I'm thinking doing custom exhaust for my alti so if won't give me CEL I will remove the cat for better performance perhaps?.

Note : It's not illegal to remove the cat here.

Thanks

Post by **1125Altima3.5** » Mon Sep 07, 2009 4:42 pm

unknow wrote:Hi,

I'm just wondering if I removed catalytic converter from the exhaust would I have a CEL on?I'm thinking doing custom exhaust for my alti so if won't give me CEL I will remove the cat for better performance perhaps?.

Note : It's not illegal to remove the cat here.

Thanks

Yes, it will throw a CEL. I would buy a real time OBD2 monitor so you can keep tabs on any other codes that might come up.

Post by **unknow** » Mon Sep 07, 2009 5:07 pm

Oh , I have BD GT so yes I can monitor any other codes that I may get but still it's not nice to see the CEL everytime you start your car.

I'm waiting for Stillen Header for sedan it has no cat on it and with flange it should not bring the CEL on, Do you think their flange would help also to by pass the exhaust cat sensor?.

Aslo I think I read somewhere there aren't any sensor beyond the header?

Post by **rcboy514** » Tue Sep 08, 2009 6:46 am

if you just remove the third cat it wont throw a code because the third cat is unmetered.

Post by **dldjros69** » Tue Sep 08, 2009 8:20 am

rcboy514 wrote:if you just remove the third cat it wont throw a code because the third cat is unmetered.

Anybody got a diagram, i have no idea which part is which.

unknow wrote:Note : It's not illegal to remove the cat here.

Here or Outside U.S is not good enough? where ya from?

Also No need to note its not illegal, its your car. oh and screw the laws.

Post by **unknow** » Tue Sep 08, 2009 8:31 am

dldjros69 wrote:Anybody got a diagram, i have no idea which part is which.

Me too If anyone could provide us with diagram I would be very grateful

dldjros69 wrote:Here or Outside U.S is not good enough? where ya from?

Also No need to note its not illegal, its your car. oh and screw the laws.

I live in Bahrain http://en.wikipedia.org/wiki/Bahrain

Post by **rcboy514** » Tue Sep 08, 2009 11:35 am

well I say that, but I just noticed you have a 2.5 so i'm not 100% sure.

I can't find a pic of the underneath side of a 2.5

Post by **unknow** » Tue Sep 08, 2009 2:54 pm

^ I will try to take pic of under my car

btw dldjros69 I just notice that you already asked me that question before and I already give an answer in BD Thread, Your really have bad memory man :P

Post by **unknow** » Tue Sep 08, 2009 6:48 pm

I took some pictures they are not very clear but better than nothing?

??

Post by **Hussain** » Tue Sep 08, 2009 8:06 pm

all you really need to look at is if theres any sensors connected. with the 3.5SE theres only 1 cat that doesnt have sensors and its the biggest one, the one right after the Y-pipe....
Modified by Hussain at 6:10 PM 9/9/2009

Post by **dldjros69** » Wed Sep 09, 2009 3:01 pm

http://i27.tinypic.com/2jg8kll.jpg

ok that is from the front of the car to the back.

The first silver piece is where the header connects to the "b pipe"?

what the heck is the rest of it?

where is the cat?

Is there a cat in the header?

Post by **Hussain** » Wed Sep 09, 2009 3:10 pm

assuming its the same on the 2.5s as it is on the 3.5se, here is a pic of my cat after i took it off and the flat part with it..... that was the only flat part of the whole exhaust system

Post by **dldjros69** » Wed Sep 09, 2009 4:10 pm

ahhh thats the part i was thinking about.

That part is flat on my 2.5 tooo.

Why is it so flat? Can i take that part off with out throwing a SES?

that part = Garbage

Post by **maxentropy** » Thu Sep 10, 2009 7:33 am

Yeah you can take that bit off without throwing any CELs due to the fact that there are no sensors from the beginning of the Y-Pipe down all the way to your exhaust. Hence you can own a 3.5 and replace the Ypipe and have no issues with CELs.

Post by **maxentropy** » Thu Sep 10, 2009 7:35 am

If you take either of the first two cats off you will most likely throw CELs due to sensors up there

Post by **kscott** » Fri Sep 11, 2009 1:50 pm

The following is from reading the service manual:

On the QR25 there are two cats, total.There are a total of 3 O2 sensors.They're hooked up as: cyl head ---> sensor #1 ---> cat #1 ---> sensor #2 ---> cat #2 ---> sensor #3 ---> tailpipeThe ECM can test both of the cats' function by using O2 sensors #2 and #3.

The first cat is a 3-way catalyst (handles all types of pollutants).The second cat is for hydrocarbons only.

Post by **Hussain** » Fri Sep 11, 2009 3:41 pm

i must be interpreting this wrong. a sensor in the tail pipe? like by the tips at the end of the car? if thats what its saying then its wrong because people have put exhaust on the 2.5s without throwing a CEL.... i cant really go into details on the 2.5s though because i have a 3.5se and thats the only one that i really know the sensors and stuff on.

Post by **dldjros69** » Sat Sep 12, 2009 2:18 am

maxentropy wrote:Yeah you can take that bit off without throwing any CELs due to the fact that there are no sensors from the beginning of the Y-Pipe down all the way to your exhaust. Hence you can own a 3.5 and replace the Ypipe and have no issues with CELs.

Its coming off when i get enough money to buy the stillen axle back.

then i will be out!!!!!!!!

Post by **Throckmorton** » Sun Sep 13, 2009 3:22 am

Hussain wrote:i must be interpreting this wrong. a sensor in the tail pipe? like by the tips at the end of the car? if thats what its saying then its wrong because people have put exhaust on the 2.5s without throwing a CEL.... i cant really go into details on the 2.5s though because i have a 3.5se and thats the only one that i really know the sensors and stuff on.

You are thinking too much here. Look at this as a flow chart, as to where the exhaust gasses flow, and flow thru as the exhaust gasses leave your engine.

cyl head ---> sensor #1 ---> cat #1 ---> sensor #2 ---> cat #2 ---> sensor #3 ------------------------------------------------------------------------------------------------> tailpipe

You are correct, there are no sensors at the exhaust tips. I hope this helps explain it.

Post by **Hussain** » Sun Sep 13, 2009 1:44 pm

oh ok. thanks i knew something didnt sound right lol

Post by **Hussain** » Fri Sep 18, 2009 2:40 pm

UPDATE!!!

i was just under Aron's 2.5s Altima coupe like 20 min ago... the 2.5 is different then the 3.5. the pic i posted earlier that i took off, on the 3.5se there are no sensors to it but on the 2.5s there is a sensor. so you cant take any cats off the 2.5s without throwing a check engine light.

Removing catalytic converter from the exhaust?

Removing catalytic converter from the exhaust?

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