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Discussion Starter · #1 · (Edited)
Turbo flutter noise

2016 with 41k, just started a new noise that sounds like it's coming from the turbo. It's a flutter type noise, gets faster with RPM, and generally happens under a slight load. I can cause it to stop by varying the throttle position. To date it only happens once per drive cycle, usually around town at moderate speeds.

Best way for me to describe the sound is when kids used to put playing cards in the spokes of their bicycle tires. Very noticeable in the cab which leads me to believe it's turbo related.

Does not cause a CEL, and there is no change in temps or oil pressure when it happens. Never lasts longer than 10-20 sec. It's difficult to predict and capture a video.

I do have GDE's latest tune with the turbo brake that engages anytime coasting above 2k rpm. Not sure it's related.

Any help or insight would be greatly appreciated.
 

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A monitor like Banks Idash is very helpful in situations like this. Usually something well change like boost, exhaust manifold temp, vgt vanes, etc. Mine had a very similar issue when I switched tunes, the fix was to unplug the egr air flow control valve.
 

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Im not sure if it well cause a cel that depends on tuning. But unplugging requires a decent flat head screwdriver and some time its not easy unfortunately. The valve bolts on to your intake manifold. It looks like a throttle body on a gas engine.
 

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I would take a look as best you can at all the pipework to see if anything is damaged, leaking or in the case if wastegate, stuck in open position.


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I don't believe that Variable Geometry Turbos (VGT) have wastegates... Correct me if I'm wrong. Here is a quote from Honeywell Garrett, the manufacturer of our turbo.

In a wastegate turbo, an actuator is used to open and close a by-pass valve to divert exhaust gas. This ability to restrict the amount of gas reaching the turbine makes it possible to regulate boost by controlling the rotating speed of the compressor.
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Honeywell 3rd Generation VNT™ Turbo
In a Honeywell Garrett® VNT™ turbo, a row of moveable vanes
positioned around the inlet of the turbine wheel can be adjusted instantaneously to vary the exhaust gas flow through the turbine wheel. As a result, it is possible to regulate the flow of gas to make a VNT™ turbo act like a small turbo at low speeds – thereby supplying greater levels of engine boost – while at higher speeds, the turbo configures itself automatically to deliver the performance of a larger turbo.
*
In any case, I would expect overboost to cause a CEL.
 

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I don't believe that Variable Geometry Turbos (VGT) have wastegates...
That is correct, no wastegates on a VGT.
If I'm not mistaken, they are more susceptible to barking (or "farting") when boost pressure forces it's way back through the impeller. Commonly heard when on/off the throttle hard.
 

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Discussion Starter · #9 ·
That is correct, no wastegates on a VGT.
If I'm not mistaken, they are more susceptible to barking (or "farting") when boost pressure forces it's way back through the impeller. Commonly heard when on/off the throttle hard.
That's what google told me, but seems it's mostly when off the throttle. Mine is under light throttle, and a little bit different noise. I appreciate all the feedback, and I'll do what I can to capture video.
 

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That's what google told me, but seems it's mostly when off the throttle. Mine is under light throttle, and a little bit different noise. I appreciate all the feedback, and I'll do what I can to capture video.
The flutter is totally normal with a VVT turbo. The sound is from the vanes being put in the position to kill boost. The sound is more or less cavitation of the air flow bottoming out. As others have mentioned, a wastegate is how a normal turbo deals with boost management.

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That's what google told me, but seems it's mostly when off the throttle. Mine is under light throttle, and a little bit different noise. I appreciate all the feedback, and I'll do what I can to capture video.
make sure all your fittings are tight on the pressure side of the turbo. you could have a hose leaking at certain amounts of pressure as the system develops positive air pressure in the manifold.

For example, @ 6psi, the system does not leak, but at 7psi, it leaks - the pressure drops to 6, leak stops until the pressure builds again to 7 etc... etc.... hence your flutter. random guess here so take it at face value. simple stuff to check.
 

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Discussion Starter · #12 ·
The flutter is totally normal with a VVT turbo. The sound is from the vanes being put in the position to kill boost. The sound is more or less cavitation of the air flow bottoming out. As others have mentioned, a wastegate is how a normal turbo deals with boost management.

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Mine happens under throttle, and didn't start until 41k.
 

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Mine happens under throttle, and didn't start until 41k.
It is common for a VGT turbo to flutter on deceleration or a quick release of the throttle thereby allowing boost to want to 'back out' of the intake into the turbo. It becomes more obvious if you are running an aftermarket CAI/Filter. However, that type of flutter does not sound like what you describe. If it's at part-throttle or in a boost condition, I would look for air leaks like someone suggested. Whatever it is, I would say it's not normal and probably needs to be tracked down for sure.
 

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I don't have a flutter but do have a growl especially in reverse under a load. It has done this since new. I've bought it to the attention of the service manager and he said unless it get worse or throws a code not to worry about it.

It's annoying but no difference in four years.
 

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Mine does it under a load up hill or pulling a trailer. Got it on video see what you guys think
Hi: Traxm... Mine only does it when it's very cold out... like below freezing. Only then when decelerating between shifts. Sort of an Er, Er, Er, noise. Haven't heard it yet this year, but then don't have the "Black bra" installed yet either. Winters not quite here yet!!!
Dieseldragon North shore of Lake Erie.
 
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