VQ Hiss or other rattle?
 

Hey all,
My question for those with noticeable VQ hiss… is the VQ hiss a constant hiss on decel or a “burst” of noise. My car would rattle for 30 seconds straight if I was on decel down a long hill

https://imgur.com/gallery/SWHPvrY

I’ve had a rattle noise on deceleration at low RPM since I bought my Z a few years ago. Haven’t managed to track down the culprit and I never thought it was VQ hiss. It’s less of an airy hiss, more of a metallic rattle. It’s tough to capture on video with the noise of the bypass valve. You can hear it at the halfway mark and again towards the end of the video.

My exhaust setup: stock headers, non-res TPs, Invidia Gemini with 2 extra Vibrant resonators clamped in… this setup should be pretty “mild” with minimal rasp/hiss since the Gemini is quiet AND I’ve added extra resonators. That’s why I’m thinking this isn’t VQ hiss and is a different rattle.


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I'm having a hard time hearing anything suspicious there. Did you try the same thing with A/C off?

VQ Hiss or other rattle?
 

Yes the noise is there all the time.

I found some posts on Reddit and other folks seem to be having similar noises. See my comment on my post. Pretty sure it’s just VQ hiss. Kind of disappointing that the Gemini (quietest catback?) with 2 additional resonators still hisses so much. Oh well!

https://www.reddit.com/r/370z/s/7hbHCe6ZbQ


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Odd.
I have Invidia Gemini V2 and the only hiss I ever experienced is if I'm pushing the car very hard and if the climate control is on, then I hear some hissing when letting off the gas - I suspect it might be due to the A/C compressor spinning on a bit higher rpm's. Otherwise I have no issues with the said exhaust and VQ combo.

Im running AAM resonated test pipes and have a noticeable "hiss" on decel when letting off the throttle it is a short airy noise, not long or extended burst its really not even intrusive tbh and my Z1 14-lb flywheel makes more then enough noise to cover it up once it gets hot :rofl2:

Do you have stock cats still? The hiss that everyone talks about is more prominent when switching to HFCs or TPs


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Hmmm my noise seems more metallic than airy but I suppose it could be the same thing. My test pipes are unresonated so that could make it worse in my case.

The sound will also continue to ‘rattle’ for as long as I decelerate or coast <2500 RPM. (Think coasting/engine braking down a hill)


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I had that until I installed ART pipes.

Best improvement ever!

I'm on stock cats.

Hey don’t be trying to get me to spend more money…


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Art-Pipes are nice although expensive to buy new, a couple forum members have listed their "lightly" used sets up here for sale. I got a killer deal on the AAM parts a year ago so I picked them up and have never looked back

That’s how I ended up with my Z1 non-res pipes. Needed a set when my old GTM pipes cracked, and these were available locally for cheap.

Sounds like this hiss/rattle is “normal” so Ill try to ignore it in the future haha


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Dude that hiss BS was no good on cheap test pipes.

I drove to the end of the street after install and drove back to the shop and took that **** off. I couldn’t stand it.

I bought used ART pipes of FB market place for the Z1 DE header. I also had VQ ART pipes on the factory VQ header and it sounded killer.

VQ Hiss or other rattle?
 

I wonder if the noise is a product of lower quality test pipe (thin wall tube?) or simply due to the straight though non-catted design. Seems like it’s noticeable on resonated test pipes and HFC too


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I developed the hiss which sounds like quick metallic rapping imo like a leaking exhaust gasket, immediately upon installing high flow cats. I brought it to my exhaust guy to verify none of the gaskets were leaking, they were not. Luckily mine only happens for a couple hundred rpms around 2000 rpm during decel.

From what I've read ,it culminates from the headers/cat area where the sound is actually produced and heard so it doesn't matter what else you have installed downstream as the sound is not coming from the tail pipe(s). Seems to be exhaust pulses hitting the exhaust piping walls in the component bolted the the header.