Strange idle exhaust noises...

[FC3S Murray]

So here is the deal,

I have a HKS cast exhst mani bolted up to a Turbonetics 62-1 that mates to a custom 3'' RB down pipe with a V-band flange.

When I start the car up when it is cold I here a very annoying audible "pinging" that obviously is the extreme pulses of the exhaust gases that is heard through the exhaust manifold. It is not sparatic and is linear with the rpms. I have ZERO exhaust leaks from my mani, turbo and DP(this was my first assumption but verifed last night both by feel and visual since it was 29 *F outside and you could see any warm air if it was leaking).

It goes away when the car is driven and warmed up. I know I sound like a pussy complaining about this but it just sounds like shit when started cold(kinda embarrassing when people want to hear it fire up lol). I wonder how I can fix this and if anyones FC does the same thing.


My timing at the pulley is set at factory 5* ATDC while my Power FC map is set at 12* at idle. Split is at 0.
Idle AFR is 12.0:1.
RPM is 900 rpm
Exhaust ports are ported as well via Titanium TT


Man it is annoying. Thanks for looking

[Mobius]

What wastegate? Just throwing this out there, but it sounds like something is slightly loose on or near your exhaust (wastegate actuator maybe, not familiar with FC's anymore), and is tightening up when everything expands.

I'm having a similar problem, except with a coolant leak on my turbo. If it's colder than about 45*F outside, my car will pour white smoke from under the hood until it's warmed up. Still haven't found the damn leak.....

[FC3S Murray]

WG is an hks"fake gate" 50mm external. Just replaced the gaskets on it last January and they are tight. Felt last night with hands around entire gasket area. hmmm??

[TitaniumTT]

I would've said exactely what Mobius said if he hadn't beaten me to it. It wouldn't be anything leaking, but the valve flutering around inside the WG,

I has a similar rattle with my 6-port N/A..... it was a missing e-clip on the actuators that would rattle around. Drove me batshit insane until I found it.

I think Mobius is right though, something just SLIGHTLY out of whack that tightens itself up each and every time she heats.

So where are you with your Breakin Sean? Ya know I've got ~2500 miles and my second dyno coming up tomorrow

Slacker

Edit - 2,863

[FC3S Murray]

Originally Posted by TitaniumTT

but the valve flutering around inside the WG,

That valve is pretty beefy bro and I just replaced the 10psi spring on it before the build. It did not have very much free play at all when seated. I will have to investigate.

Originally Posted by TitaniumTT

So where are you with your Breakin Sean? Ya know I've got ~2500 miles and my second dyno coming up tomorrow

Slacker

Edit - 2,863

you SOB . I offically have..................1005 miles on her

Slowly getting there but she is getting more responsive. My tune is damn near perfect, within .2 AFR for all cruise to atmospheric pressure cells. Smooth as a babies ass!

[FC3S Murray]

edt... because i am an idiot

[FC3S Murray]

Well shitty find, my DP flange is cracked AGAIN! I guess when the flange gets in tomorrow I will compare it to the one that BASTARD(forum name) put on this set up. I will give it to my welder and tell him to cut the old one off and match this new flange perfectly to avoid any fitment issues.

I do know what the problem is and why my exhaust DP flange is cracking. All I have for exhaust system supports are the 4 donuts on the muffler hangers in the back. I think the bumpy roads around here and no support on the pre-silencer section are causing the DP flange to flex and eventually crack.

My Racing Beat pre-silencer has two exhaust hangers on it BUT I have no support rods on my chasis?????

Can someone shoot me a pic of there FC's underbelly so I can see if the stock support rods were welded on or bolted on. Either way I am gonna have to fabricate something to support this exhst system.

[TitaniumTT]

Hey Sean, if at all possible, I would have everything tacked up while it's on the car. Here's what I would do..... Where the cat was, there should be 2 8x1.25 nutserts on the frame rails. I used a length of 3/8" stainless rod welded to my presilencer, then the factory donuts and those factory hangers. I didn't like the idea of mounting the exhaust to the trans that far back, I wanted the exhaust to be able to move sperately from the trans there. So the first thing that I would do would be to add some support there.

After that, I would go to Verocious Motorsports and order up one of thier flex couplings and have that welded in place.

Then after everything is fitting the way it should, I would replace the V-band. Tack everything in place in the car then pull it all off for welding. Stainless likes to move when it's welded but I'm sure your welder knows that and will compensate with some fairly heavy tacks and alot of them.

At the end, you'll have a better supported exhaust, and one that will move more indepantly than the engine when she torques