Engine Acceleration Noise

[rburrow87]

My '13 BRZ has started making a new noise in the last couple of days. I haven't been able to nail down a way to replicate it every time, so I'm not quite ready to try taking it to the dealer yet. Figured I'd see if anyone has had the same problem.

It seems to come in at or just over 3000 RPM, and goes away as it goes over 4000 RPM. The sound actually sounds as if it's coming through a tube, which I don't think comes across in the videos. It also seems to originate directly ahead of the left (driver) side in the engine bay. I had someone in the passenger seat and they said it sounds like it's driver side as well.

You can hear it start at 0:14 in this video:

[ame="https://www.youtube.com/watch?v=25TRHlTOzGU"]BRZ Acceleration Noise 1 - YouTube[/ame]


And this video was a lucky one because it was particularly loud:

[ame="https://www.youtube.com/watch?v=lbl-Y__FB84"]BRZ Acceleration Noise 2 - YouTube[/ame]


No CEL and nothing else seems out of the ordinary. I don't notice any kind of loss of power or anything when it's making the sound. I went around tapping on stuff and haven't found anything loose that sounds anything like it yet. I tried to find examples of DI seal failure sounds, but those all seem to be more like a firecracker than this. Unless this is the early stages of it?

I changed the oil after starting to hear this because it was about time anyway. Didn't see or smell anything odd. The only mod I've done close to when this started is swap the clutch slave cylinder with a smaller bore, but I can't find a way to tie any of that that to this sound.

[strat61caster]

I honestly can't hear anything worth writing home about but if I had to guess it is the Variable Valve Timing which can create a odd metallic resonance sound as it changes it's uhh variance.

Lengthy discussion here and in the links, keep reading it's not all about aftermarket tunes. Not really a problem but rather a quirk.
http://www.ft86club.com/forums/showthread.php?t=59475

[rburrow87]

Thanks for the link. I originally thought it was something with the VVT system, but dismissed it for some reason I can't remember anymore. The noise does seem similar to the videos in that thread, and the RPM range seems about the same too. Hard to say for sure if it's the same thing though, gotta hear someone else's do it in person.

My biggest concern really is that I've had this car from new since April 2014 and I'd never heard this noise before until a couple of days ago. Or at least it wasn't loud enough to hear it over anything else. The only drive/powertrain mod I have is a Borla catback which is pretty smooth and quiet sounding.

Since there's no CEL though, might as well see what happens since I'm well within the warranty period.

[chaoskaze]

sounds like something is clicking/resonating.... but not from the engine thou. O.o Take it to dealer.

[BRZnut]

Sounds like a metallic rattle to me from the exhaust..maybe the heat shield under the car?

[carma143]

I've had, for the longest time, a rattle coming from the dash area at around 6k rpm, sounding slightly hollow. I've taken out the front screen radio, fiddled with the wires behind, taken out the Start-Button and checked behind, looked under the wheel, and checked to make sure the rear-view-mirror was properly tight, which seems to loosen once a year.

I tinkered with the Start-Button and the stuff behind it yesterday, and tightened the rear-view-mirror, and haven't heard the sound since.

[rburrow87]

Interesting... did tighten the mirror a few weeks ago because I got tired of seeing it vibrate. Sounds like it's outside the cabin though.

Doesn't come across in the video, but it really sounds it's some kind of intake noise. It's coming from the driver side which is where the air box is, and it's definitely coming from under the hood somewhere. Rolling the window down actually makes it harder to hear, so I'm not sure what that says. A friend of mine following me said the exhaust sounded really nice but didn't hear anything different when the noise came on. I do have a Perrin panel filter, but I can't imagine it's really any louder.

I'm close to just chalking it up as some weird noise these motors can make. I do hear what I think is a lifter tapping at idle now, but it's very quiet so I don't know if it was already doing that and I only noticed because I'm looking for something. That only seems audible when it's a hot low idle, so it could be totally normal.

At any rate, I'm just going to keep monitoring everything and see if anything changes.

[Packofcrows]

Originally Posted by carma143

I've had, for the longest time, a rattle coming from the dash area at around 6k rpm, sounding slightly hollow. I've taken out the front screen radio, fiddled with the wires behind, taken out the Start-Button and checked behind, looked under the wheel, and checked to make sure the rear-view-mirror was properly tight, which seems to loosen once a year.

I tinkered with the Start-Button and the stuff behind it yesterday, and tightened the rear-view-mirror, and haven't heard the sound since.

Im trying to find this rattle too!



For rpm sound, could it be clutch fan or whatever its called? Mine whirled oddly on pickup so i welded it.

[carma143]

Originally Posted by Packofcrows

Im trying to find this rattle too!



For rpm sound, could it be clutch fan or whatever its called? Mine whirled oddly on pickup so i welded it.

No idea man! It's also possible I did only a temporary fix, or I haven't been listening hard enough. I took apart and put back a lot of panels over the past few days. It could be nearly anything. If the sound does come back then maybe I'll check all the emergency supplies (food&water rations, flashlight, spare glasses) that I fit under the trunk floor. Maybe it's vibrating on some metal object.

[Rifle]

Used to have an exhaust rattle, where a small piece of my cat broke off in my pipe. You could only hear it rattle at 700-900 rpm, anything higher, you just couldn't hear it. You sure it's on the inside/engine bay?

[pinski]

Mine does the same thing, between 3500-4000rpms. Funny thing, it changed tone after I tuned the car.

[Stang70Fastback]

I've had a weird rattle that sounds like it comes from the shifter area since I bought the car. Only comes in above like 4-5k RPM. I keep meaning to try to figure out what it is, but haven't yet.

[Ultramaroon]

I experienced that exact same sound a couple times earlier this year. Both times were after hammering through some high-g turns. I had a wild-assed theory about air bubbles in the valve timing mechanism. 0.o

[stevesnj]

Do you have a license plate relocate kit? could be a loose tag screw