engine rattle/vibration sound @ coldstart

[beat1]

Yeah I know... another thread about rattles. I know because I read alot of them before making this one and I didn't really find my answers.

So I have a 14' BRZ with 21k miles, I bought it used 4 months ago, during the winter here in Montreal. I learned myself and by reading on this forums that this engine makes alot of weird noise during start-up/coldstart and i'm fine with that.

Recently, it started doing a weird vibration/rattle noise, seems coming from the engine, when I first start the car in the morning or after it sit a couple hours. It does it only for rougly ~10 seconds from what I guess is during the "cat pre-heat". Anyways, it doesnt sound cool at all, it's pretty loud in the car and it happens 100% of the time, every coldstart.

Recorded a small video in the engine bay, just after I started the car, @ 20 seconds, you can hear the engine sounds changing at then @ 31, its settle and idle nicely. Use computers speakers or headphones, its alot better.

Monday, I let the subaru dealer check it and they called me today saying they couldnt hear or reproduce the problem lol. The only thing they did is reflash the car with the latest TSB that fix some idle issues that I didnt really care about in the first place.

Inside the car, harder to hear, you can see the RPM jump when it stops :

Any ideas? I think I might try another dealership nearby... Theres no CEL for now but that noise wasnt there before so i'm a bit worried.

[humfrz]

Hello beat1 ....... welcome to our strange noise generating machine .....

Do you have any exhaust/power modifications .. ?? If so, what ..??

If not, have you done anything to the engine or exhaust lately .. ?? (other that what the dealership did)

Have you changed gas supplier lately .. ??

If I were going to start messing with stuff, I'd start by checking the exhaust heat shields, followed by the exhaust connections.

From your video and description, it sounds like my FR-S starting up ....


humfrz

[beat1]

The car is stock, 100%. Have not done anything to it.

Like I said, I know this car makes all kind of noise, especially during coldstart, even worse when its really cold outside and it doesn't bother me, but that rattle/vibration noise wasnt there before, or at least it wasnt THAT loud inside the car.

[Imrac]

I wonder if you have a loose heatsheild around the headers or over pipe.

You may still be under warranty. I am fairly certain factory warranty is transferable.

[humfrz]

Originally Posted by beat1

The car is stock, 100%. Have not done anything to it.

Like I said, I know this car makes all kind of noise, especially during coldstart, even worse when its really cold outside and it doesn't bother me, but that rattle/vibration noise wasnt there before, or at least it wasnt THAT loud inside the car.

OK. I'd suggest you get it up on a rack and check the exhaust heat shields and exhaust connections.


humfrz

[ZZT86]

Sounds kinda normal to me, the revs are dropping & the resonance from the intake is also changing which is what I think is causing the noise you're experiencing.

[BRZnut]

Sounds like my car...actually if that was a cold start it sounds better than my car!

[beat1]

I had to go to another dealership and they found out its a metal sheet or heatshield, they have to order it and change it under warranty. Good news