I've had my setup since Oct 09 (Berk HFC, 350zhr y pipe, hks rear). Prior to that I had stock cats and 350zhr ypipe and hks rear.

Just today evening I started up the car (about 18 hrs since I last drove it) and turned on the a/c to cool it up. It was prob on for about 5 minutes when I went back to garage and heard a rattle... seems it was coming from y pipe area. The underbody of the car has not hit any stone or rock or bumps AFAIK since I am the only driver.

When I sat in the car (wife in passenger seat), rattle went away slightly.

While driving and even at lights, no rattle. I guess the exhaust was warm now?

Stopped for about 3 hrs at family place. On the way back home, started car and after about 1 - 2 minutes, heard the rattle again. Driving home and at lights it was fine, no rattle.

Could it be cold exhaust or just something loose?

Will check in the morning when I startup the car.

 

you got a sound clip of that setup?

 

it is prob one of the bolts is coming loose, make sure everything is tight and all of the clearances are good.

 

Maybe heat shields?

 

i had this issue when i installed the coupe midpipe on my car.. its a bar that is suppose to protect the midpipe incase it falls.. since its not secure in there it wobbles causing the side bars to hit this metal piece.. hence why u get the rattle.

 

Well I visited a local reputed garage and they checked it out.

The mechanic started the car and put it on the lift when we heard the noise. He checked all the bolts and pipes and everything seemed fine except the mid pipe. He even used some sort of stethoscope to listen to the midpipe. He said there is something loose inside the resonator box and hence needs to be replaced.

I have to give my car in for 110,000 kms service soon so will get Infiniti to check as well.

It's item #8 in the attached pic. Should I also get new gasket rings and mounting rubber if I need to replace the midpipe (or center muffler pipe as per the pic )

Thanks!

 

Do u have a coupe midpipe?

 

sorry forgot to mention I have the stock oem midpipe.

 

Buy a coupe midpipe. They are cheap and it will add a little to your exhaust note

 

the hr ypipes are known to rattle

 

check if your hr y pipe have the rubber damper that stop the vibration.

 

I've had this setup for almost a year now and the HR y pipe has been fine.

It's the stock resonator on midpipe that is the culprit.

 

I think it may be heat sheilds too. As the exhaust warms up it expands and tightens up next the the exhaust. If you still have them...

 

My car does this. it did it went the car was bone stock. On very cold mornings the exhaust would rattle only if i went above 3k rpms while the engine was cold. I replace the mid pipe with coupe pipe, still does it. changed from stock y pipe to hr pipe, still does it. Its either something loose in the muffer, cat(s), or the exhaust shields.

 

sound clip!