Startup: Loud metallic (rasp?) sound from middle/under of car, not from exhaust
 

[ame="https://www.youtube.com/watch?v=dBqBxJQest0"]Metallic Startup Sound - YouTube[/ame]


Hi folks,

In the first minute of startup or so, I have a semi-loud metallic sound that comes from the middle of the car. I hear it every time I start up cold. The noise does NOT come out of the back of the exhaust. I get out and go to the back of the car, and I can tell it doesn't come out of the exhaust. When I get out of the door and drop to the ground to listen, it sounds like it's coming from the underside of the engine area. It sounds like some cheap ricer exhaust note but I just can't for the life of me understand why it wouldn't be coming out of the tail pipe?

I should add that I now have a turbocharger, PTUNING headers, and have had some issues with my setup. Here's a thread where the other stuff is discussed, including the small possibility of an exhaust leak.

Thank you for any input you can provide folks!

-Chad

Post the link maybe?

It's OK, I remember that thread.

Likely case: You have a clearance issue. Exhaust components vibrate. One of them is hitting the front crossmember. They expand when hot, and either the clearance issue goes away, or it simply pushes up on the crossmember harder and turns into an inaudible rubbing issue.

Less likely: Your exhaust leak is getting real bad.

Take a video. It's hard to diagnose without hearing it.

Whoever did your tuning and install sounds like they made a f*cking mess of both.

On the Ptuning kit, the turbo sits behind the front crossmember, next to the transmission. This is where you describe the location of your noise.

Oops! Here's the link:

http://www.ft86club.com/forums/showthread.php?t=105984

I'll make a recording of the sound with my camcorder as soon as I can ensure a cold start.

Well, if that was my car doing that, I reckon I'd put it up on jack stands and let it sit overnight. Then crawl underneath and have someone fire that puppy up.

Where is noise is coming from and what's making it, should be obvious.

Then I'd take it back to the dude that did your install and have him fix it.

OR

Get one of those old shade tree mechanics, that is retired over there in Sequim, to grab up some gasket material, gasket sealer, some bailing wire, a small crowbar and a big f _ _ _ _ _ _ hammer and fix it the old fashioned way ...... ;)


humfrz

Here's a walk-around audio-video of the car during a cold startup. I should add that the noise isn't particularly well represented in this, it seems much louder and more obnoxious with human ears. My little camcorder can't do it justice. Also, the noise is present at other times too, at certain throttle/RPM positions I guess. It's not simply a cold start phenomenon but that is one easy way to make sure it happens.

[ame="https://www.youtube.com/watch?v=dBqBxJQest0"]Metallic Startup Sound - YouTube[/ame]

It's really unlike any sound I would expect out of my car given the reputation of the Perrin 2.5" resonated exhaust, and on top of that -- my turbocharger, which itself is a pretty good muffler.

I apologize for bumping this but I'm really hoping to see some opinions, so I thought I'd bump it now that I have embedded a Youtube video in the opening post.

Well now, johnmk ...... I can't hear on your video, what you're describing.

My recommendation as mentioned above, still stands ..... you're are going to have to get up close and personal with that sound, to peg it.

(if you haven't burnt your wrist or forearm ....... you haven't gotten close enough ..... :D )


humfrz

I appreciate your opinion ... and I'm pretty sure you need better speakers. :) I will of course keep trying to figure this out, and then I'll post back when I do. The installer/tuner listened to the video and said something sounds off, so I'm pretty sure that I'm on the right track here now.

There is NOTHING WRONG with my speakers ....... it's my EARS that don't work too good anymore...... :(

Yep, after you get it sorted out ...... let us know what was causing the sound.


humfrz

There is NOTHING WRONG with my speakers (so my wife says) ....... it's my EARS that don't work too good anymore...... :(

Yep, after you get it sorted out ...... let us know what was causing the sound.


humfrz

One last bump, I promise. Please if you have a moment, listen and tell me if you think I'm hearing nothing out of the ordinary.

Thank you!

I haven't laughed so much since my granny died.

So, besides taking and posting a video, what have you done to try to figure out what is making the sound .......??


humfrz

Hi humfrz,

It's a long journey to their location for me, it means giving up an entire day's income (possibly more, in fact), arranging for a loaner car, and several other dislocations in my life and others' lives. Understanding everything I can possibly figure out, and having all my ducks in a row beforehand, makes this process as efficient as possible in several domains. My expenditure of time is very tightly managed and must be planned for in-advance for reasons that aren't reasonably shared here.

I had the installer-tuner listen to my video, and I think he agrees with me that something's wrong, but I'm unsure if he is convinced. I'm having them do several things to the car when I take it back to them, so I'm trying to have all my ducks lined up in a row. Once they open the car's belly I want them to do everything at once, including add electronic boost control, fix the exhaust leak if there is one, fix the exhaust rattle if there is one, check the sway bar/end link noise, add gauges, possibly some sensors & whatnot such as oil temp/pressure, boost gauge, and this, that and the other.

On top of that, I'll have them re-tune the car, as I'm not happy with the car's performance at the moment. Boost comes on too late, and I'm missing about 20-25% of the low/mid-range torque that my turbo kit usually makes. That's either caused by an exhaust leak somewhere, or perhaps a suboptimal tune, or maybe something else is wrong with my car. It was the first time they'd tuned the PTUNING turbo kit in an FRS/BRZ. I should probably have gone with the AVO kit, since it's one they're very familiar with and seems to carry less risk of long-term engine damage since it peaks at about 250whp, but I have the PTUNING kit so I'm going to make the best of it.

I want to trust my installer-tuner, but the fact is I've lost a bit of trust, so I feel like I need to do all my homework since I think I'm on my own. With 5 minutes of research they should have seen quite clearly that their dyno numbers were quite inferior to what others get with my car/turbo kit. At that point, I should have been notified and presented with the facts, and possible solutions. That's what I would expect, and that's not what happened. I was told the car was done, there are some occasional funny new noises, but it's probably fine. They're right about the clutch chatter noise and maybe the sway bar/end-link noise, but the exhaust rattle noise, well that's not right. I was also told that in their opinion the kit was not as responsive as the AVO kit, in their experience -- the AVO kit is the one they specialize in.

I'm very appreciative towards PTUNING, and Freddy/Toan at PTUNING in particular, who have tried to step up to the plate and help me, but they're on the opposite side of the North American continent, and there's only so much they can do. Ultimately, if my dyno numbers don't substantially improve in the re-tune with my current tuner, I'll have PTUNING do an e-tune. At that point, it's an admission of defeat. I will have paid for two tunes and paid nearly 2 grand for the privilege.

-Chad

Sounds like a resonance in some component of the exhaust or its actually hitting on chassis somwhere.

If it ONLY occurs on a cold start then get your tuner to reduce the "post start ignition timing" from -15 to -4. should sort it.

They may also need to reduce the "maf offset in gear and in neutral down to 20" in any cells above 20 and also reduce any idle table cells above 1200 to 1200.

buy just dound the post start ignition timing should stop that resonance.