I got the same problem, i hate it! sounds like a freaking ricer! Im gonna modify my greddy with resonators hoping that would make it quieter.

 

has anyone got similar problem like i got? i got used to it but would be good if i can get rid of the problem.

I get this rattle/hiss/snake/buzz or whatever you call it. my car got similar symptom like Zmonster posted.

it only happens when decelerating (engine brake), between 2200rpm and 1800rpm.

say im driving down the road in 5th/6th gear or so, or everytime i stop at lights and etc, the rev drops to 2200rpm and below. it starts buzzing from 2200rpm fades away at around 1800rpm.

it may not seem like a much of headache but when cruising around the car sits between 1800rpm and 2200rpm a lot of times with foot off the accelerator, and yes it is very loud. i can literally drive the car buzzing like a rattle snake for as long as i want, especially when going down hill where i can keep the rev between 1800 and 2200, and not touch my accel. the noise instantly disappears if i touch my accel.

there's no leak, no metal to metal contact etc, and yes it goes away if i put my stock cats back on. i've seen/driven quite a few z's with test pipes and i dont mind a bit of rasp but mines a bit extreme compared to others.

anyone got similar issues? lol

 

I had a VERY similar issue, when decelerating ...this rattleing noise would come out, sounded like a leak or something... turned out to be the flex pipe...We spot the source of the sound by using a hose, putting your ear on one side and touching different parts of the exhaust on the other side... got that fixed by replacing it with a straight pipe. Now i was left with the raspy sound when accelerating from 3k to 4k... installed two resonators right before the x pipe, got it fixed .. it tone down the sound alittle bit though, it was alot of frustration but i was happy in the end..

 

Got any pics of the greddy? I have the greddy too with test pipes and am wondering how to fix this rasp

 

I did some more digging and found some info that may be related..

I was checking the engine using cipher to datalog all the signals to see if there were anything happening when the noise comes into play, and found two interesting things.

1. When the noise is occuring, the ignition timing advance is around -4 degrees.
2. When the noise is occuring, throttle position sensor voltage drops to below 0.8v.

Now, thinking of the noise again, that sounded very much like spark plugs firing (!). And looking at the ignition timing, the ignition timing stays at 0 or 1 advance in other revs but it drops down to -4 around 2000rpm, and at the same time the noise kicks in. As soon as i give it a slight touch of accel, the ignition timing changes to around 30 or so and the noise instantly goes away.

I am guessing that its firing the spark when the exaust valve is opened, hence making the spark audiable from outside at aroudn 2000rpm.

Another thing i found is the throttle position sensor reading. It sit at around 0.8v with foot off the accel in other rev, but it drops down to around 0.75 when the noise occurs. It seems that the throttle map is set in such way.

Also another guess is that may be adjusting the throttle map using osiris can fix the problem, by making the the throttle to open slighly more (0.8v) and ecu may change the igition timing from -4 back to 0 or 1 or somewhere around there.

I already tried adjusting the ignition timing in the timing map of osiris, and found that the timing table was only used when accelerating. looks like im gonn have to do some trials with my throttle map, hopefully i can get this problem fixed.

 

Guys i got a question, i got my Megan Longtube headers installed last week and im getting this weird buzzing/vibrations on the passenger side??? All the bolts are tight and im sure we got everything done right but wat is that noise? It occurs at low speeds and sometimes just sitting at a stoplight. It isn't bad and it only happens once in a while, but it's sucks when you have a female in the car and they wonder why you car sounds like it's falling apart lol. Anyway is that buzzing natural? Thanks!

 

I think I had the same problem after installing my headers. After changing out your headers, cats, and exhaust, the whole system may sag and a part of your exhaust might be rubbing against the crossmember or some other piece of metal which creates that rattling noise. If that's the case put some spacers on the crossmember. Also, check to see that your test pipes aren't hitting the heat shields.

 

+1 same thing happens with my test pipes (tanabe y pipe). The hissing sound on decel in gear is normal. I've learned to live with it. If you really don't want to hear it put it in neutral (if you have a 6 spd), the sound will go away.

 

The thing is when i ran stock headers and Topspeed Test pipes i didnt get any rattles from the passenger side. When i replace the stock headers/testpipes with Longtube headers i got this rattle/vibration coming from the passenger side (engine bay)? It occurs when the brakes/clutch are engaged and sometimes when im accelerating/deaccelerating at low speeds. My thought is that it's the oem cat support brace. My longtubes have the slot where it hooks up but i lost the support brace from the test pipe install. My friend has the megan longtubes and oem cat support brace with 0 rattles? U guy think thats the cause of the vibration? Thanks

 

i have a 04 roadster with Nismo cat back , and i too have the rattleing sound. It first started having a new grawl/rattle at deceleration around 2500 rpm , then it got progressivley worse to the point of at start up it sounded like a damn honda civic with a bad exhaust leak. I took it to the dealership that installed the Nismo exhaust and of course it was the damn flex joint on the Y pipe. Thankfully it was covered under warranty. Of course they had t order it so i should get it on this week sometime.

 

totally have it after installing my resonated test pipes, i'm learning to live with it...

 

so tony@motordyne ! would your xyz pipe with the resonator help ? does the resonator affect hp in any way ?

 

you might be on to something. many aftermarket exhaust manufacturers cut costs by using cheaper thinner low quality grade stainless steel. This drastically alters the sound of the system. made in china products like titek (SP Engineerings brand) have about a 1.2mm thickness for the piping, JDM and OEM use about 1.5mm, we (ARK) use 1.7mm w/ 304 stainless. this is why a lighter exhaust system isnt always the way to go. people seem think that getting a exhaust that is 20 pounds lighter is better because of weight reduction but where do you think all that weight is being taken away from? lower quality products that are lighter is better than losing 20 pounds for the track? i dont think so..

 

It's the grandchildren of WWII gremlins.

I do get some rasp with my combo. Top Speed headers, Berk TPs, TXS catback, but I find it seems to be much more throttle position oriented than rpm.

 

I have the same issue and I agree that it could about throttle. If I accelerate at a consistent rate I dont get any rattle at any rpm. But if I floor it or step off the gas completely, then the rattle comes back. Usually around 2200-2700k or 3500- up. Whatever it is it sucks! And BTW resonators dont help at all. Before the resonator i had a nice deep tone and some rattle. Now I have a almost deep tone and just as much rattle. The guy that put it on didn't even charge me cause he couldn't figure it out.

 

So did anyone find out wats causing this??? I have Bassani with xpipe and megan longtube headers with the cat support brace and i get this BUZZING when i decelerate. Thing is i only get it when im in gear. As soon as i put it in neutral buzzing stops???

Example-40mph in 2nd gear, let off gas and BUZZZZZZZZZZZZZZZZZZZ then i put it in neutral and it goes away??? Anyone got any ideas?

 

bump for a fix on this!!!

it's also driving me nuts!!!

 

I've taken my system down to the exhaust shop on 4 different occassions and still cannot isolate the issue.

I've have had the flex pipe replaced to see if this fixes anything to no avail.

I have an X-pipe currently. If i replaced the X pipe to 2 individual parallel pipes (true dual setup) from the cats, would this make me loose any torque/hp?

 

So... What about ARK's true dual? Could you guarantee that it won't have this issue when paired with test pipes?

 

haha the money question is asked..