Patrck C

I noticed that my w206 c300w4 is making some loud-ish ticking noise which to my understanding are Direct Injection Injector noise? For the w205 it seems to be 50/50 chance between injector and the wrist pin issues, now here comes the w206.
Really only noticeable if I am not playing music. No trouble code, no performance issue.
Noise charcterized by the following:
1. High frequency tick, very distinct on cold start from inside/outside the car. After warm up/idle down distinct from inside of the car, not so much outside. Sounds very typical to DI sound.
2. Very noticeable ticking when engine is under load(accelerating, going up hill), from 1200-2000 rpm, doesn't change loudness with regards to engine temp.
3. Goes away when coasting(lift-off from throttle), not ECO coasting, engine still technically on.
4. Distinct from engine humming, but it is very hard to record, and fairly easily get covered over at high rpm by engine humm or road noise. It sounds way louder to my ears vs on video, which I really can't even tell its there on recording, so I am not gonna bother posting.

My w204 have the same tick at idle but it doesn't get louder underload(item 2), nor do my work car which is a Chevy also with DI.

I recently drove the car around with no music on(which I really never do) to identify a interior rattle I was getting and realized this engine noise. So I am not sure if it has been like this since new.
I can't conclude if this is just High Pressure Fuel pump + Direct Injection combo being fairly loud on this car, or something is wrong.
I connected Xentry, and apaprently w206 does not have a sensor reading for injector duty cycle, volume or really anything injector related, so I couldn't diagnose further.
Brough it to the dealer, classical "It is normal". They Don't have any W206 I could test drive to compare it against, so I am wondering if your engine are also making this sound, and can we conclude it to DI?

Patrck C

Finally managed to get a recording, its the constant high frequency, slightly muffled ticking/clacking sound in the background throughout the entire video. Had to use an old android phone I had to record it, apparently newer iphone's noise cancellation is too good and removed it. This is recorded from interior, all windows closed, the noise is slightly more pronounced in real life.

I ruled out the purge valve, unplugged it, went for a drive, sounds the same.

ACSchnitzersprt

I am getting something similar. I just got my car on Monday and noticed when sitting in the garage setting my settings and favorites. I thought someone was knocking on the garage door (yes it was open, just not all the way). When I looked under the hood, I found the noise coming from the left mid-upper side of the engine. I believe that is the turbo, but I can barely change my own oil.

I had a w205 prior and never heard anything like this.

I also experience some light noise in reverse or idling. Almost like an electric cars reverse sound.

Wish I had more input, but it sounds like we’re going through similar things. I barely have 100 miles on it, so I was going to wait until breakin was over.

Patrck C

Given that your signature says C43, I am thinking your guess might be right, and you might be having two noise at once. A Electric motor sounding noise near the turbo could either be the waste gate servo motor, I have some similar noise when the engine kicks into start/stop, its like a fast sudden gear grinding sound. Or simply actually be the turbo, I believe C43 have a secondary electric turbo charger, which is infact an electric motor. Idk if the electric turbo is supposed to kick on when idle though. These are quite pronounced with the hood open in my experience.
Though C43 and C300 have quite different engines, if you are also hearing a ticking sound inside the car when accelerating at low speed or when in Park then that's probably the sound I am describing. Maybe you can talk to your dealer as well, but I bet they will just say its normal. I've had them saying its normal twice, but when I got to drive a loner c300, I found the lonaer to have much less pronouced ticking.