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!

 

[Weveeee]

Hey guys, now that it’s 2025, has there been consensus on what the actual issue is with the throttle tip in squeak? I have a 24 CT4V BW with 4k miles and it’s making this noise only at throttle tip in. When in accessory mode (car off) it squeaks. So from that diagnosis it’s not the turbos or wastegate but must be the throttle body. Has anyone determined if this is an actual issue or just an annoyance? Would love to try to close this mystery out for the whole community.

 

[SML604]

There are two issues, apparently. The throttle body is one and the turbos are other. My dealer addressed both problem areas.

It is still heavily warrantied. I would take it in and get it resolved, but as far as I was told by the dealership, there isn't any imminent risk.

 

[Weveeee]

There sre two issues, apparently. The throttle body is one and the turbos are other. My dealer addressed both problem areas.

It still heavily warrantied. I would take it in and get it resolved, but as far as I was told by the dealership, there isn't any imminent risk.

Super helpful! Thanks man. How long was your car in for?

 

[SML604]

Super helpful! Thanks man. How long was your car in for?

A while...I think they had the car for a total of 5 or 6 days over 3 trips. And parts needed to be ordered.

This being said, this was last summer so there probably wasn't the knowledge base within GM that exists now. Hopefully they can get you in and out efficiently.

 

[Jdeee]

Hey guys, now that it’s 2025, has there been consensus on what the actual issue is with the throttle tip in squeak? I have a 24 CT4V BW with 4k miles and it’s making this noise only at throttle tip in. When in accessory mode (car off) it squeaks. So from that diagnosis it’s not the turbos or wastegate but must be the throttle body. Has anyone determined if this is an actual issue or just an annoyance? Would love to try to close this mystery out for the whole community.

It is the throttle body. As soon as I went to the Soler TB then this noise went away.

How many miles do you have. I’ve heard from some that the noise goes away over time.

 

[Weveeee]

It is the throttle body. As soon as I went to the Soler TB then this noise went away.

How many miles do you have. I’ve heard from some that the noise goes away over time.

Super useful man. That sounds pretty definitive then. I’ve only got 4k miles, 2024 early build. It showed up at about 1k miles. When I use the throttle a lot it will go away but then reappear my next drive at the same sound level. What are you hearing mileage wise where it’s going away?

 

[Jdeee]

I started hearing it around 4k miles too and swapped throttle bodies at 8k miles. The noise didn’t go away until after I swapped. I’m not sure how long it will take to go away.

 

[Weveeee]

I started hearing it around 4k miles too and swapped throttle bodies at 8k miles. The noise didn’t go away until after I swapped. I’m not sure how long it will take to go away.

Wait so are you saying your swap to a new TB at 8k did not fix it? Did you go aftermarket after the swap and then it went away?

 

[Jdeee]

Wait so are you saying your swap to a new TB at 8k did not fix it? Did you go aftermarket after the swap and then it went away?

No, I’m saying that the noise was noticeable for 4k miles until I swapped to the Soler TB at 8k miles.

I took it to the dealer and got a new drivers side turbo and the noise didn’t go away. As a matter fact, the new turbo had the wastegate rattle where as the turbo that I had before did not.

 

[Weveeee]

No, I’m saying that the noise was noticeable for 4k miles until I swapped to the Soler TB at 8k miles.

I took it to the dealer and got a new drivers side turbo and the noise didn’t go away. As a matter fact, the new turbo had the wastegate rattle where as the turbo that I had before did not.

Copy that. I’m hoping they’ll allow only a TB replacement when I go to the dealer. I’d rather not swap a turbo as that’s much more major. Did they provide any details as to what the TB issue was? I assume a manufacturer tolerance error.

 

[Jdeee]

Copy that. I’m hoping they’ll allow only a TB replacement when I go to the dealer. I’d rather not swap a turbo as that’s much more major. Did they provide any details as to what the TB issue was? I assume a manufacturer tolerance error.

They never diagnosed the throttle body as the issue, I had to determine that myself. Per usual, the dealership was highly incompetent.