Brand new BRZ rattling sound

[OwlDance]

Cheers for mentioning me into this thread. Long winded post but I hope it makes sense. Disclaimer, not an engineer and am a major car novice at best.

Right, so I want to clear up immediately that the thread by cat94 makes a different sound and MAY or MAY NOT be related to this rattle that occurs here. His occurs during interaction with the accelerator, not typical engine acceleration. I noted that I could produce a similar noise if my engine RPMs were below 3K by lifting off or pressing the accelerator suddenly, whether it was light to moderate. I've never been in a situation where I'd stomp the accelerator and hear so I can't speak for then.

I concluded that the noise was simply just some weird mechanical function in the car, because this car is apparently known for very weird noises but I wasn't suffering any direct mechanical issues. I believe this is most likely unrelated to the issue. It's like a mechanical sound of something activating/deactivating. However cat94's noise does seem rather pronounced compared to mine. This is not the rattle that you get while accelerating.

My thread that I posted was about an acceleration hesitation when transitioning from 2K-3K RPM during an INITIAL acceleration (but not a flutter). That is, if the car was at a stop then proceeded to accelerate, there would be a point in roughly gear 2 or 3 at ~2.5K RPM where the car simply seemingly minimizes accelerating before continuing again a moment later. Once it's past that threshold it doesn't happen again so long as I don't come to a complete stop OR, if I let the engine coast at roughly 2K to 2.3K RPMs for a little while. Coasting at that RPM before trying to accelerate again brings that weird slowdown. I reckon this has to do with the direct injectors (FA20 uses port and injection) switching on and off when it wants to coast and hypothesized it was a result of bad DI seals, which seem to be a common problem for the FA20.

The videos I posted show some very dramatic fluctuations in the tachometer during that issue. Again, mine simply slows down before continuing on again. The only time I flutter is if I'm at 2K RPM and "stomp" the accelerator without gradually increasing the throttle which might just be bad practice to begin with (woo lugging and detonations on our engine as it seems to function better at higher RPMs because of the high compression ratio?)

Personally, I've avoided my flutter entirely by cruising at 3K RPM (seems to offer good power for immediate acceleration while avoiding the flutter range) or if I am cruising at or near 2K RPM, I downshift and bypass that area entirely. I should note I'm on an AT transmission but I drive entirely 100% in manual mode.

As I was typing this I resumed my search of the original issue, and of course I would find that one thread that's more closely related to the issue than what I've found before.
http://www.ft86club.com/forums/showthread.php?t=66620

It seems like you might have a bad DI since you have the exact same "rattle" noise as a lot of these other videos. If your tachometer actively FLUTTERS like the videos then I would almost certainly chalk it up to a bad DI as the evidence suggests and take the car in. And I don't like to inflict unnecessary concern but this post (and video) shows just how delicate the DI seals are that could easily result in issues like this, whether during factory install or even during replacement. http://www.ft86club.com/forums/showthread.php?t=42849

What DID stand out in the DI video is that the carbon build up on the seals might not be bad; it leads me to believe that the seals set into place with a proper break in according to the manual. But because there hasn't been any documentation on how people have broken their cars in versus DI failures, this is 100% speculation on my behalf. With that in mind, the action of "testing" the car could very well exacerbate my half issue. It's a bit of a catch 22.

Crap. Now I'm paranoid again.

[HKz]

^ tl;dr....op has a brand new twin, unlikely DI issue especially since he mentions this occurs at low RPMs which mostly uses the PIs...

basically if you own a twin ya better become deaf to weird noises...as long as you check your fluids (probably temps if you're tracking) just go out and drive..refinement was not a priority for this platform.

[csol]

Originally Posted by HKz

needs louder exhaust

Well i got one, bought the invidia n2 catback just havent installed it because i don't want them to be like 'oh yeah we cant hear anything' or 'oh yeah its your exhaust that is causing it' even tho it isn't

I'll keep this thread updated once the service (2days)

[OwlDance]

Originally Posted by HKz

^ tl;dr....op has a brand new twin, unlikely DI issue especially since he mentions this occurs at low RPMs which mostly uses the PIs...

basically if you own a twin ya better become deaf to weird noises...as long as you check your fluids (probably temps if you're tracking) just go out and drive..refinement was not a priority for this platform.

I don't have the numbers but I do believe another user said that DIs kick in very soon. At higher RPMs it combines port and direct for more power. There's an 8 minute video on the 86 by Toyota that explains it.

I should stress that in the video of the thread I linked has the flutter, rattle, and tachometer waver at practically 2500 RPM with a confirmed bad DI seal, and that videos in the thread I posted a while back had some with confirmed DI issues. Listening back to some of them, they also make a very similar noise to the audio provided in this thread. All of which occur at about 2500 RPM, which matches the datalog that OP posted. He also posted on my thread that he had the exact same issue.

[HKz]

Originally Posted by OwlDance

I don't have the numbers but I do believe another user said that DIs kick in very soon. At higher RPMs it combines port and direct for more power. There's an 8 minute video on the 86 by Toyota that explains it.

I should stress that in the video of the thread I linked has the flutter, rattle, and tachometer waver at practically 2500 RPM with a confirmed bad DI seal, and that videos in the thread I posted a while back had some with confirmed DI issues. Listening back to some of them, they also make a very similar noise to the audio provided in this thread. All of which occur at about 2500 RPM, which matches the datalog that OP posted. He also posted on my thread that he had the exact same issue.

[ame="http://www.youtube.com/watch?v=zc8aUxBZlsU#t=50"]2013 Scion FR-S | D-4S Technology Explained - YouTube[/ame][/QUOTE]

ok yes there is some combination of DI/PI at low speeds but at higher engine speeds it is DI only...either way, I still haven't heard of any "issue" from the OP, it is all just him being paranoid about a "noise" that goes away after...just drive if the car ain't falling apart while you're WOT then nothing to worry about

[OwlDance]

Originally Posted by HKz

ok yes there is some combination of DI/PI at low speeds but at higher engine speeds it is DI only...either way, I still haven't heard of any "issue" from the OP, it is all just him being paranoid about a "noise" that goes away after...just drive if the car ain't falling apart while you're WOT then nothing to worry about

I think I may be incorrect that it uses port and direct at higher RPMs for more power (the video provided seems more official than the one I recall), but cheers for the link.

I do maintain that if he's actually feeling the car do something odd besides sound (that tachometer slowdown on my car can be felt more noticeably under harder acceleration, I can only imagine the tachometer flutter is even worse) then there's definite cause for concern. My suspicions come from the numerous symptoms that do appear to line up in more than coincidence (the confirmed DI failures, RPM flutter at identical locations, and audio rattle), but I guess we'll have to wait and see what the dealer says for csol.

[csol]

Originally Posted by HKz

ok yes there is some combination of DI/PI at low speeds but at higher engine speeds it is DI only...either way, I still haven't heard of any "issue" from the OP, it is all just him being paranoid about a "noise" that goes away after...just drive if the car ain't falling apart while you're WOT then nothing to worry about[/QUOTE]

I'm not being paranoid about the noise its very real and not only noticeable to myself but others too.

I'm aware boxer engines are loud and this issue wasnt present when i first got the car so its a very obvoius different.

I have no fluctuations when accelerating but it makes the exact same noise as the other guy so it might be somehow related to DI

Tomorrow is service day will update you all.

[csol]

Took it into service today,
Tech went for a drive with me and said he couldnt hear it.

I told him its there and asked him to drive it, he drove it and could hear it. You really cant hear it from the passenger side.

He said "your injectors are fine doesn't sound like knock"
He suggested i remove the soundhose and that its the resonator making that noise.
Also that its hard to determine what it is without hearing from the passenger side.

Told him I'm not happy so they are going to run some diagnostic.

Going go get a second opinion -_-

[8RZ]

Test driver another one and see if you can hear it.

[csol]

Originally Posted by 8RZ

Test driver another one and see if you can hear it.

Thats what he is going to do apparently but yeah i told him it wasn't like this when i bought it.




I'm going to remove that stupid sound tube and change the intake pipe to a perrin one.

[scottryan]

- Buy pillow foam from local crafts store
- Cut into blocks
- Open truck, look directly upside down at the ceiling of your trunk space, you'll see in the very center of the truck, a hole with daylight coming through, that's the 3rd brake light mount. Stuff the foam all up in it and voila.

[csol]

Originally Posted by scottryan

- Buy pillow foam from local crafts store
- Cut into blocks
- Open truck, look directly upside down at the ceiling of your trunk space, you'll see in the very center of the truck, a hole with daylight coming through, that's the 3rd brake light mount. Stuff the foam all up in it and voila.

Did you even bother to read my post, this isn't related to anything to do with vibrating or rattling reverse light.

Anyway for anyone here who is coming across this issue I have the solution.
The issue is the stupid noise generator tube that goes into the cabin.


That is what was causing that sound issue, after replacing the intake hose with an aftermarket intake and removing it sound was gone.

The tech at Subaru hinted at this and I followed his instructions and removed the sound tube and now the sound is gone.

It makes sense because if you plug the hole like some people have been doing the issue "magically goes away". Which you might think is a bad approach in solving the issue but the actual rattle is coming from that box.

So removing the whole tube or plugging the hole is a solid solution.

[cwik]

Hi OP, did your rattling noise ever sound tinny or metallic noise? I'm curious if my issue is the same as yours:

For reference, he's how it sounds without the rattle:

It rarely happens, but when it does it:

• Only happens when I'm on the throttle, and generally when I'm a bit harder on the throttle. If I lift off the throttle, the noise goes away.
• If the noise starts happening, I can get off the throttle for 5 or 10 seconds and that generally stops the noise from coming back for another few months. If I lift off for 1 or 2 seconds and get back on the throttle the noise keeps happening (like in the video).
• Only happens when I'm accelerating in low-to-mid range RPM, never high up in the RPM range. It has never happened while idling.
• Only seems to happen when the engine is already warm.
• Seems to affect the power output of the engine, but maybe that's all in my head.

Car's history/my hunches:

• The car is stock, and I've followed the suggested maintenance schedule by bringing it to the dealership.
• I don't really drive it hard at all.
• I've never seen the "check engine" light.
• It doesn't sound deep in the engine, but rather just a loose metal shield or something dealing with a resonant frequency.
• This has been happening probably since 2013 or 2014.
• I have not had the recent valve spring recall performed.

It's due for its last maintenance under warranty in a week and I'd love to be able to give the service department more information than those videos.

[csol]

Originally Posted by cwik

Hi OP, did your rattling noise ever sound tinny or metallic noise? I'm curious if my issue is the same as yours:

For reference, he's how it sounds without the rattle:

It rarely happens, but when it does it:

• Only happens when I'm on the throttle, and generally when I'm a bit harder on the throttle. If I lift off the throttle, the noise goes away.
• If the noise starts happening, I can get off the throttle for 5 or 10 seconds and that generally stops the noise from coming back for another few months. If I lift off for 1 or 2 seconds and get back on the throttle the noise keeps happening (like in the video).
• Only happens when I'm accelerating in low-to-mid range RPM, never high up in the RPM range. It has never happened while idling.
• Only seems to happen when the engine is already warm.
• Seems to affect the power output of the engine, but maybe that's all in my head.

Car's history/my hunches:

• The car is stock, and I've followed the suggested maintenance schedule by bringing it to the dealership.
• I don't really drive it hard at all.
• I've never seen the "check engine" light.
• It doesn't sound deep in the engine, but rather just a loose metal shield or something dealing with a resonant frequency.
• This has been happening probably since 2013 or 2014.
• I have not had the recent valve spring recall performed.

It's due for its last maintenance under warranty in a week and I'd love to be able to give the service department more information than those videos.

It sounds like the videos i posted in the first post.
Remove the sound tube and check if your issue went away.