CT4-V Squeaking and stumbling from idle (2024 4BW)

[jadis192]

And your 100% it’s that exact part making the noise vs the TB? It’s my understanding that even when in service mode, the only part that moves is the TB. Not the WG.

You can see the arm move on the wastegate aligned with the noise. Here is a picture of a wastegate and it's arm.

The arm clearly moved during diagnostic startup. The TB is under the intercoolers, your have to remove the top of the engine to see them.

Photo of a sample wastegate attached.

LF4 engine, you can see passenger side wastegate in this photo:

 

[jadis192]

Additional video of the chirp on throttle tip-in.

 

[Weveeee]

Additional video of the chirp on throttle tip-in.

OMG. Have you basically figured out this whole thing without having to replace your TB nor Turbo!? I have an appointment setup but is this the true fix! How could it have been this simple and no dealer figured it out?

 

[ngoni]

How could it have been this simple and no dealer figured it out?

I think you give the average dealer service department far too much credit. The real sad fact is I'm sure GMs support engineers have been called in to assist a bunch of times with this and none of them have taken the time to actually figure out the problem. They just tell the dealer to keep replacing parts until the noise goes away.

 

[jadis192]

OMG. Have you basically figured out this whole thing without having to replace your TB nor Turbo!? I have an appointment setup but is this the true fix! How could it have been this simple and no dealer figured it out?

I don't want to speak for dealers, but I've documented the noise with the wastegate arm. GM should have a TSB for this, replacing turbos and TBs seems pointless.

 

[jadis192]

OMG. Have you basically figured out this whole thing without having to replace your TB nor Turbo!? I have an appointment setup but is this the true fix! How could it have been this simple and no dealer figured it out?

Let us know what the dealer does. I am editing my response as I learn more. The Arm and "bell" that I am showing in the pictures is the wastegate ACTUATOR and arm for an internal wastegate in the turbo. Now, with this being said, it is entirely possible that the wastegate within the turbo, is the problem. Which would explain why they replaced turbos for some people.

Ok, I don't want to act like a mechanic, I am really just an owner solutioning. Either way, my videos do show the noise coming when the actuator arm moves, whether the noise is from the actuator arm and bell, or from the actual wastegate itself inside the turbo who knows. Report back your findings!