Hi all. Just purchased a 2009 G37x a few weeks ago from a local Infiniti dealership. I have 30 days of warranty on the car and have been extremely ocd when it comes to the smallest noises with this car.

Today I noticed this noise. I have no idea what it is but when I press the gas and take my foot off, it Makes a "pfffffttt" sound. Is this normal?

 

I don't hear what your referring to but from what I do hear doesn't ring any bells to me.

 

Sounds like the VQ hiss to me. Are there any exhaust mods done to it? Mine didn't become pronounced until I put on RHFCs.

 

Car is all stock. Here is a video I found on YouTube that sounds exactly like my car. It's basically that hiss noise but much more pronounced. Is this normal and nothing to worry about?

 

I would say it's fairly common, some are more pronounced than others. Mine definitely has it I can tell you that. It's not as pronounced now after the tune, not sure why that is, but it's still there.

 

Have your exhaust checked for leaks

 

There could be an exhaust leak, but being an untouched OEM exhaust... probably not.

The noise is a resonance coming from the engine when it winds down to idle, and the sound is exposed through the exhaust. The OEM exhaust does a pretty good job of masking it, although if you have freakish OCD Super Ears, you'll probably think twice. I don't hear it in your first video, and although I'm half-deaf the second video very clearly demonstrates The Hiss. (Capital H, LOL)

OP, the VQ37HR is a noisy engine. It sounds like a broken diesel until it warms up, after which there are all kinds of odd creaks and groans, not just in the engine, but the whole car.

Relax, man. The G37 is a fine car, but a luxury sedan it's not.

 

Car is fine. Enjoy!

 

I can barely hear it in your video...but it is there. I don't think it's an issue.

Your exhaust sounds awfully muted for a G. I have CAI but swear the G should have a deeper/louder exhaust note than that

 

mine makes that sound, ever since i installed the FI Catback and i LOVE IT ( i had the hfc before that). I don 't think i noticed it when stock, so you must have a very good ear
but yes i say normal

 

My 37x did and still does hiss, even after cats. It's a very common noise with these cars. Some say a Y pipe fixes the issue.....