Have you tried it without the O2 sesnors yet?? Anyone come up with any other solution? Now that it's warmer in my area I hear it even more clearly. It's really starting to drive me crazy!!

 

IMO it has nothing to do with the cats because I have Xerd Headers and Borla True Duals and I still have that noise between3-4K.Very Very annoying. For those of you you who are not familiar with Xerds,you can go catless since its a long tube header.

 

I have Borla TD and I have the noise. I install Kinetix cat. I still even more noise. I got under the car and have my wife rev the engine.

MY noise come form H pipe. This is a small gap that no matter now tight you clam it, it still leak.

It is where the notch is on the buttom of the H.

I am going to muffler shop and will have it weld.

I can not say where the noise come from for the people with other cat back system but more than likely it is some sort of gas leak, I think?

 

I'm glad you found the problem for your car but most have the problem under load between 3-4K rpms. Revving it won't duplicate the noise for me. I had to take the dealer service rep. out for a test drive before he could hear it.

Stupid question coming....Is there a way to run the car on a lift in gear to replicate this noise? Other than a dyno machine? Is there anything like that out there?

 

I put mine on the lift and had my tuner check from underneath while I was revving between 3-4K and he thinks its coming from the heat shields due to resonance,exhaust pulses from the exhaust gases(something like that).
350ZRB you must have a great marriage if you went under the car and your wife didn't try to run you over and steal the car from you.

 

Did he come up with a solution?

 

You might have some thing .....thinking its with the heat shield. After my car is fully warmed up it doesnt do it . I got BRM headers , rt cats, stillen dual . It only does it when its cold

 

don't know if anyone has brought this up... but in Nismo website, they put an end note at the end of their cats product page.... it says that their high flow cats will produce a metal rattle noise at around 3500 - 4000 rpm as well... and it is NORMAL!

so I guess most of the high flow cats will produce this kind of metal vibration due to the resonance....

cheers,

richie

 

Thanks for the compliment. We have four kids and she still let me buy this car. Is she great?

Anyway have H pipe welded AND THE NOISE STILL THERE!!!!!!!!

The guy at the muffler shop suggest for me to replace the two gasgets. The ones that I reuse. Between the cat and cat back, the gasgets are 4 pieces of thin sheet metal. I can see that where the bolts are the are seal well but in the middle, there are not as tight as the both ends.

So I will try that next.

 

Well, I just realized a few days ago that I also have this horrible sound coming from my car. The only reason I hadn't detected it sooner is because I hadn't stood outside while someone else was driving my car. Well my friend took my Z for a quick spin and as soon as he took off I heard it!! It is HORRIBLE. I just thought something was loose because it sounds like if there were something loose, I thought it was the muffler. Sounds like the muffler is either loose or rattling inside.

Well I don't have RT Cats, Here is my current setup:
Crawford Plenum
Japtrix Y-Pipe
Japtrix Mid-Pipe
UR Crank Pulley
K&N drop-in

Next week I am going get my DC Sports headers installed, I want to put it on the lift and try to find where it is coming from. Any suggestions on what exactly to look for. I have been reading about the 02 sensors, I will see if I can try that out. If anyone else has any updates PLEASE POST!!!

 

why didn't you just have them install new gaskets while you where there, couldn't be more than a few minutes and a few bucks???

 

My kinetix made my exhaust sound raspy from 3.5-4.5k paired with Nismo exhaust. I took them off for a number of reasons but i will be trying Crawford cats next. Havnt ever herd of Crawford cats being raspy at all.

 

I don't think it's a problem with the cats as everyone is claiming, because I have the noise and I only have the Nismo cat backs.

 

Man, I wish someone could figure out a solution. There's not many things it could be. I'm just a mechanical idiot.

 

Bcause when I was at the shop; the noise was not there.
I drove home put in in the garage and had my wife rev the engine, then I hear it.


But this morning driving to work, I do not hear it.


So I will leave it alone now.

 

It is deffinitly the cats.. Put them on, raspy, take em off, no more rasp. It's the cats.

 

Does anyone experiencing this noise have ALL new exhaust work? meaning the exhaust gases do not go through anything OEM, other than the head.

What I am getting at is... I used to have an Integra GSR and one day it got a rasp while revving or under a load, but not while holding the RPMs steady. Turns out there was a TSB out there for it that said to replace the "B" pipe, what joined the two pipes coming from each pair of cylinders into one pipe right before it goes into the cat... like how in a 4-to-2-to-1 header setup would be... its the factory "2-to-1" piece, it was made up of an "internal" pipe and an "external" pipe, so it was a pipe in a pipe kinda... I think maybe to reduce noise... but anyhow, the inner pipes were evidently coming in contact and vibrating against the outer pipes.

I'm just thinking that maybe Nissan has some portion of their piping that has this similar setup as the GSR did.

 

Did you have any luck eliminating the noise after installing the headers??

 

Was it the head shields? Were you able to fix it? It's just driving me crazy!!

 

Just a thought, but do u guys think it could be the fact that our motors have Continuously Variable Valve Timing? So whenever we punch the gas, we are getting more air in and out of the motor, thus causing a buzzing noise. As opposed to just half-throttle driving over the same RPM band and getting a normal sound. I've heard some VTEC cars with headers,no cats, and exhaust and they aren't very quiet. Their buzzing is very, very loud. But only when their VTEC kicks in. And it also depends on the exhaust. I know that Greddy makes a pretty quiet exhaust system because of their muffler. But my friends insist on custom high-flow cat-less exhaust with knock-off mufflers.

So that's my input on this whole debate. Correct me if I'm wrong.

Also, I have Helix Test Pipes and a Borla TD exhaust on their way and I don't plan on installing the Helix TPs untill this debate is resolved.