Twin Turbo Kit- Internal wastegate rattle sound

SAM@GTM · 05-21-2013, 12:44 PM

Quote:

Originally Posted by NOBLE|370Z

I have a 2009 370z, with a GTM stg2 TT kit recently installed on it. I have a boost controller with set points at 7psi (wastegate spring baseline) and 10psi. An issue that I am noticing when I take it to 10psi on the highway is that I hear a loud rattle noise above the 7psi. It sounds almost like a detonation sound (rattling metal popcorn).

There may be a reason for that since one of the actuators on one of the turbo's internal waste gate is having some issues. Apparently there's not enough clearance for it to open and close properly, so Sam and my mechanic are looking into whether or not I have a 350z bracket on it. As a result I have to set the boost controller ~2psi higher than the set point Id like to see. Therefore I dial in 12 psi if I want 10psi to show on my boost controller read out.

I'm beginning to wonder if the rattle could just be the internal wastegate rattling. However, its a really loud noise that I can hear when I'm going high speeds, so I'm not totally sure a waste gate rattle is the cause since its so small.

Could this in fact be some kind of detonation? My mechanic and I will be hearing back from Sam at some point this week to tell if we have the wrong bracket on the turbo. I'm just not sure I should be driving my car at all in case there's a more serious problem here. I don't hear the sound at the 7psi setting, so hopefully I can drive it at lower boost in the mean time.

Has anyone else had any issues with this?

I have called the shop and spoke to the technician and what is happening does not make a lot of sense. I think you have two separate issues here and they are not linked to each other. The tech stated that when he tested the actuator with a vacuum pump on the bench, it took 20psi for the actuator to move. If that is the case, then you should not be having any boost target issue or your engine should have been destroyed by now. Keep in mind that the HKS boost controller works off of boost target and is very critical for the learning process (base boost pressure) to be done precisely so the boost controller can achieve what you are asking it to do.

So here's what I suggested to him. Remove the boost controller out of the equation and just run the wastegate actuators to a pressure port to establish what kind of boost we have. That should really give us a good idea how well the preload is set on the actuator (whether it is too tight or too loose). As for the noises you are hearing, I would not drive the car until you find out the exact source of the noise. I can't see the car making a rattling noise at 10psi unless you have a fuel delivery issue and the car is running lean.

As for having the wrong bracket, we do have the right bracket as verified with the tech.

Sam

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