Engine Acceleration Noise
 

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.

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

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. :)

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

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

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.

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.

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!:D 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.

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?

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

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.

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

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

Nah I DIY'd a mount. Doesn't really sound like it's that though, you can vary the pitch of the sound with gas pedal.

It's a pretty hard mechanical sound. Very disturbing.

Has it come back since then? I seem to hear it pretty much every drive now. I've noticed that it only seems to do it, or least does it more easily, when it's fairly warm or hot out and the engine is good and toasty.

The only thing that has changed since noticing this sound is that I drive it a bit harder because I feel more confident ever since changing the clutch slave cylinder out. I can't imagine how that part could be related though.

Since it seems like the noise is from the intake, I'm wondering if it's just some goofy valve timing that happens when it's hot? I guess it's possible that it's detonation, but I've heard detonation from my Jeep due to a leaky intake plenum and that tends to be a more random popping/ticking/whatever you want to call it and under WOT at high RPM. The BRZ really only does it under light/medium load in the 2.5-4k -ish range.

It's for sure not detonation, and not related to the clutch. I haven't heard it since, I think, July. It was during a club street run and I was hammering it really hard. Once it started, it didn't matter how much I eased up.

It's a mystery to me. I hope it's not something expensive but boy, it sure sounds like it when it's happening.

The saving grace, and the reason I kept driving was because it occured in a narrow band of engine speed. About 400 RPM, IIRC.

Well it sounds like we have/had the same thing happening, only difference is yours went away! Mine only started this after I had been hammering it after the clutch slave swap because I was really enjoying it.

Maybe tomorrow, if it doesn't rain like they claim, I'll pull the airbox and all that and make sure it's not something stupid going on there. Then after that, I'll try resetting the ECU and see if that does anything. I was thinking about picking up an OFT next month to try E85, so it'd be interesting to see if that has any effect either if it's still happening then.

I'm not sure how up to date my ECU is as far as software goes considering it's a 2013 MY. It was purchased in early 2014 and you'd think they'd keep all the TSBs up to date on their inventory, but who knows. I'm kind of leery about the dealer I bought it from, and I basically just don't trust anyone else to mess with my stuff anymore, so I really don't want to go to them for anything.

Please let me know if you find anything. I need to get serious about logging.

Oh, man, I hear you loud and clear. So much to learn about the software, though. I'm new to it but will get there soon enough.

Weird, I've had the same problem every now and then. It's very hard to catch, but it's usually in the higher rpm range (5-7k). However, whenever I swap gears or disengage/engage the clutch, it goes away. I'm thinking it has something to do with the transmission. It's only happened about 2-3 times since I'd gotten the car. ~20000 miles on the odo and it's completely stock under the hood.

I've been trying to figure out if the Torque app could log anything relevant to this, but all I've really done with it so far is add oil temp using one of the write-ups here. Seems like an OFT is ideal for the data logging stuff from what I've read.

I think I could trust a fellow enthusiast if I got to know them a bit first... but that's about it. Which is pretty sad because you should be able to trust the dealer, especially with a warranty.

And yeah I know nothing about automotive software either. Could be a fun learning experience if that's what it takes to find out what's going on.

I found my rattle! Rear license plate vibration!

@rburrow87, were you able to find out what caused this noise?

I had this happen to me to too long ago, same sound. But my range of occurrence was 3.5k to 4.5k rpms. After much freaking out and getting under the car, it turned out to be an exhaust leak between the midpipe and front pipe.

I forgot about this thread. I found mine. It turned out to be the clutch master return spring. Amazing considering how loud it gets when it's happening. I just tap/touch my foot on the clutch pedal and 'poof,' it's gone.

http://i.imgur.com/mnEZC3b.png

Sorry if I'm reviving a dead thread. Did you have any exhaust modifications? My noise started after auto x and before I had my catback installed. Not sure if it's coincidental or if something during autox caused it. Car had 1400 miles at the time. Like you it was only in certain ranges, though mine seemed to stop after 4k. Also had a honking whirring kinda noise and it still occurred when stationary while revving. Seems to only occur when the car is hot, that's not consistent either. I think it might be the TO bearing. It hasn't gotten any worse and I'm at 8k miles...

I'm thinking about doing a header and a tune soon, but I want to make sure my trans is solid first. 2nd gear is a bit knotchy and makes a bit of a thud when cold. 5th is consistently knotchy. Also had a weird sucking noise at high rpm with the AC on randomly. Sounds like a taser mixed with a vacuum. Idk how else to describe it. That only happens occasionally...

This started a day after I did a full exhaust upgrade. I'd get under your car ,after letting it warm up and revving it a few times, and look for condensation at the connection points; that's how I found mine. Fixed that and the noises disappeared.

That "honking" noise, does it sound like a low pitch "whoop"? I'm sure there's a thread on here about that. just keep in mind, what you were doing when this happened. It'll help narrow things down.

For the notchiness, try letting your car warm up and settle a tad longer.

that's my 2 cents.

Me Too...
 

My 2015 BRZ makes this noise occasionally. The first time I heard it was the day after I bought the car (new). After two years, it has become more frequent (or at least I notice it more).

The condition it happens most repeatably is after I've been cruising on the highway for a long time (like an hour or longer). If I exit the highway, the next several times I accelerate (at a light or stop sign) under moderate load, it makes this noise. The noise starts between 3000 and 3500 rpm and goes away above 4500 rpm.

- It does it with 91 or 93 octane, regardless of brand.
- As someone else said, it sounds like it is coming directly in front of the driver but not inside the cabin.
- I don't notice a loss of power, but I lift off the throttle when I hear this.
- After the car cools down (like overnight) it won't do it again for a long time (until I'm on the highway for a long time again).
- Ambient temperature doesn't seems to matter, it happens in the summer and winter.

[ame="https://www.youtube.com/watch?v=aeVtZQNu_Ss"]BRZ Engine Noise 3500-4500 rpm - YouTube[/ame]

I remember searching on here two years ago after this happened the first time. It appears there are a few of us now with this issue. I brought my car to the dealer today to look at it, and they couldn't reproduce the noise (no surprise).

Read my previous post here. It's that spring. Prove it for yourself. The next time you get that sound, keep your engine speed steady and just tap the clutch pedal.

I'll definitely try that. So the theory is the spring is at some kind of resonance in that RPM band? How did you determine this is the issue?

Well, it's still a theory for your noise, confirmed for mine. I had read about it in another thread and did exactly what I'm suggesting to you.

I wonder if that spring isn't just a touch too short. A lot of effort went into designing the lightest possible clutch pedal. This could be a consequence.

Hello, sorry if this is a dead thread...
I recently had the same issue... If that was the spring, what was your fix?

No fix. I just tap the clutch pedal and move on. I would look into it if it wasn't such a rare occurrence.

After going back and listening to @C4RBON's clip again, I'll change my mind about his noise. I think I was reaching. The noise I get is much louder and obnoxious.

How loud is yours?

Can confirm I've had this sound a couple times coming off the highway. I always thought it was aggressive vvt changeover noise, but if it's just the clutch spring then that's a relief!

I don't think so anymore. I hate to be wishy washy but I think it's way more important to keep it real.

I know in my case it is the clutch spring. When it kicks in it's really obnoxious, much worse than that last clip but close to the second one.

Do you have a tune because I'm stock and don't get the vvt noise.

@Ultramaroon No, stock. Both times were from coming off the interstate after a 3 hour drive and driving around 30-35 mph in 3rd gear, rattle like my cams were woodpeckers. It could have been that I was low on oil, since my first year I spread out my intervals sometimes to 8000 miles. Haven't had it happen since 2013-14, but it's definitely abnormal when it happened.

The 2nd video that @rburrow87 made shows it perfectly, though in my case my sounds were lighter since I was just cruising and maintaining speeds 30-35, and when I'd reach a certain rpm it would rattle like that.

Hmmm... Maybe it is your clutch spring. That would be awesome. :thumbsup::popcorn:

Every time for me it was super hot underneath the hood.

Mine is pretty much the same as the clip... and it happened every time I passed 3100 RPM