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

[johnmk]

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

[steve99]

Originally Posted by johnmk

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!

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.