I have done research on this forum, but I still can't find the answer to why my car has suddenly begun rattling with increasing rpm. Most of the posts I read had issues at idle or with decreasing rpm.

The car has no rough idle issues. In fact it drives just fine on the street, and you wouldn't think anything was wrong until I begin to hit 2500 rpm. I can begin to hear the whistling sound of the primary turbo as it comes online but within two seconds all I hear is a rattling sound coming from the lower passenger side. It makes me think the waste gate is just flapping around.

This rattling occurs in all gears and consistently appears at >2500rpm and goes silent at <3000rpm when decreasing from WOT whether on the highway or street. The intensity of the rattling is directly tied to the rpm range.

My car's turbos and engine have less than 10k miles since they were last replaced with new gaskets and all. A full vacuum hose line job was done 6 years ago. All maintenance has been kept up to date and the work was performed at KDR.

The only thing that I have recently done near the turbo area was to replace the standard aftermarket downpipe with a knightsports down pipe. This rattling noise did not appear immediately since I finished that job. It's been at least 1.5 months since I did that job and this appeared nearly two weeks ago.

Unfortunately, the only rotary shop near me now in CT is IRP. It's a bit too far right now with my current lack of free time.

I appreciate any and all advice.

 

Bump

 

Is the turbo transition normal?

Take a look under the car at the Turbo Control Actuator, check to see if the e-clip has fallen off. You can do this without lifting the car.

You can see the WG actuator e-clip from the top, however if your WG were flapping around you would have very slow boost response.

 

And check to see if the pre-spool cover is tight. I had one gradually loosen up once making the same type of noise & pattern. I would suggest retorquing all of the turbo to exhaust manifold bolts while you're down there.

 

I just installed a boost gage this past weekend. The car has been fairly stock and I felt in the past that there was no rush to install a boost gage in my years of owning it.

Now I can answer the question as to my turbo transition. Right now I'm getting 10-8-8. I wonder whatever is causing the rattling noise is keeping my boost at 8psi after the transition. Either way it builds quickly to boost. There's no slow response from the boost. The rattling noise builds just as fast.

I checked the e-clip for the turbo control actuator and it's still there.

As to a loose pre-spool cover I'm not actually sure where that is. I don't see something with that label on my drawing, but I did find a missing nut on the top of the heat shield that seems to go near the compressor for the primary turbo. I'll be reinstalling that nut once I go to the hardware store to pick up t-fittings for my water coolant thermometer. Hopefully that missing nut is the source of the noise, but it just seems difficult to imagine so much noise from a small heat shield.

 

Check your turbocharger's heat shields. The thin ones that cover the turbos.
My car did this, and it was one of the shields had rusted around a bolt, and while the bolt was still screwed in tight, the shield had come away and was rattling, with a thin, tinny noise at some rpm.

*compounded on this, my car is a RHD. The steering shaft runs very close to the side of the twin turbos heat shielding. When the shield let go, it jammed against the steering shaft as I was going around a corner. I made a brown streak in my pants over that one.

 

Update. So I've done a few things to try to narrow down my rattling noise. I installed new oem gaskets at both ends of the downpipe. Replaced the silicon hoses that attach to the y-pipe. Got new couplers for the inter cooler. Replaced the three check valves with new Viton ones, and installed new silicon hoses at the check valves. New oem gaskets between the turbo inlets and the intake piping and discharge piping. Retorqued the heat shields at the turbo.

The car responds extremely well. I'll get 10-8-10 sometimes 12. It's probably time to get a boost controller. I just don't know what could possibly be wrong with a 45k mile car that leads to this rattling noise.

I know when this rattling sound happens my boost seems to dwindle to 8 pounds. This noise happens only under constant boost. Vacuum is strong at 18in and greater. Is there some other hose that sees boost that might be making this noise?

 

I once chased this same problem for some time, as it got progressively worse:

Take the lower heat shields completely off the turbo, inspect and re-torque the bolts that fasten the turbo to the exhaust manifold, paying close attention to the longer bolts through the center section, above the pre-spool valve's cover; the larger (10mm) bolts have 14mm heads/nuts and take about 30 ft. lbs., if I remember correctly--suggest consulting the FSM. If you replace any of the turbo's hardware, be sure to use the factory Iconel bolts/nuts in these locations--other materials will not hold up to the heat.

You can get to all of the turbo's mounting bolts/studs relatively easily from underneath the car and you don't need to remove the DP. If the center of the turbo assy works loose, it will make the rattling sound you've described and you will lose boost capability due to the pre-turbo exhaust leak.

 

Did you figuered this one out? Is this the sound that you had? If it was that I'd appreciate any help I can get!
I have not been able to work that much with my car the last few years but I'm going to get it running this spring.
Here is a clip from inside my car.
If you solved this, please get back to me!

 

I had this issue before and for me it was vacuum line that was loos on boost controller. So when the car got hot the vacuum hose would be soft and bled off the pressure holding the wastegate door closed and cause it to flap.

FYI it could be a few different vacuum hoses in that system, not just the boost controller/waste gate hose.

 

Thank you very much, I'll look into it on monday and keep you updated!

 

did you finally solved this noise? I have exactly the same one and it’s getting me crazy