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

[SML604]

And it is possible the noise comes back (defective parts fail, especially if there is a design issue), but I am fairly certain the turbo was the culprit in my case (upstream cause notwithstanding).

 

[obeykube]

My noise has not come back either, but, a very mechanical rattle is still present. Idk if its normal but...I'll try and take a video

 

[SML604]

My noise has not come back either, but, a very mechanical rattle is still present. Idk if its normal but...I'll try and take a video

Wastegate rattle? Mine developed a bit of an off 'turbo-like' noise that I think is tied to the simulated noise that's piped in for the louder settings, because when I turn the engine noise setting down it goes away.

 

[jadis192]

I'm one of the lucky ones to have this too, 600 miles. Any updates? Sounds like one of the turbos? To me it sounds like a belt, I am going to do some investigating this weekend.

 

[SML604]

I would say it's either the throttle body or the turbos. For whatever reason, this seems to have creep up early on a lot of these 24s. I wonder if there was a manufacturing defect on the turbos.

 

[jadis192]

I may wind up waiting until they can release a TSB or a recall? If its just the actuator, is it really more of a nuisance in the squeak or is there any real concern for damage?

 

[SML604]

For me, I was told it was the turbo itself. I was also told it was just a nuisance noise, but it was annoying enough in stop and go traffic that I was eager to have it fixed on my new car.

Given we have had enough reports of it, I would suggest that GM now knows about and should be able to deal with the matter faster than it took for me.

 

[MyThrpe]

I encountered a similar issue, which was resolved since the dealership replaced the driver's side turbo. I anticipate that a TSB will be issued for this matter in due course since multiple people have this same problem.

 

[Jdeee]

Hi all,

Long time lurker, first time poster. I've searched around this community already, but I haven't found someone else with the exact same issues (though the OP in this thread has the same noise). This being said, I apologize in advance if any of what follows is a rehash of others' experiences, but here's my story:

I recently took delivery of a 6-speed 4BW after waiting almost 2 years; however, in the month I've owned it, that car has already been in the shop twice. The car currently sits with ~1400 kms on it. It has been broken in as advised, using 91-94 octane used exclusively from major stations.

The first time the car went back to the dealer, it was 24 hours after I picked it up; I put 30 kms on the car and parked it; I came out to look at it and immediately noticed that a puddle had formed under the car. After sending it back to the dealer (and them taking a few days to find the leak), it was determined a turbo cooling line were leaking. This brings us to the latest issue....

Recently, I was driving the car when I felt a bit stumble while cruising on the highway. At the time, I noticed it, but with no warning light or message popping, I didn't think much of it. About 20 mins later, I pulled into my garage and I noticed a new squeak as I pulled in, popping up every time I hit the accelerator from idle. I heard it again, upon shutting off the car. Hoping it might just be a one-time thing, I drove the car a bit more to see if the issue would resolve itself - unfortunately, it didn't As a result, I made an appointment to take the car in. The dealer brought the foreman out to examine the complaint; it was agreed that there was indeed an issue and the car was booked in for further examination.

In trying to document the issue for the dealer, I took a video of the noise: https://youtu.be/RiYrrrMJTXA.
The squeak on revs (and on shutdown) is clearly audible; the stumble in revs is also notable at the 31 second mark.

This all brings us to the present day. The car is in the shop being gone over, with a confirmation that the low rev stumble is a misfire. The dealer has been swapping out plugs, but that hasn't fully resolved the issue. GM has also apparently told the techs that some amount of stumble at idle is "normal". This strikes me as odd.

Secondly, I've been told that GM has said that they have no record of "squeak" of the type that I'm reporting, so no one is sure what's going on. Again, this seems odd to me. After 2 model years and thousands of cars, I'm surprised I've encountered something entirely new, but I guess it's possible.

In any case, my dealer is continuing to dig in and has told me that they are looking to compare my car against another 4BW. Given that both the stumble and noise started recently, I'm fairly certain they'll find something is off with my car, but that's still TBD.

I'll post updates as I get them, but if anyone has any insights, I'd love to hear them.

This sounds like the throttle body squeak that I had. It goes away over time, think of it like a break in lol. Get in the car and hold the start button on for 10 seconds to put it in diagnostic mode. Press the throttle a few times and see if you hear the squeak, if so then it is the throttle body. Used this as a reason to upgrade the throttle body haha!