Rattling sound when cold revs
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Joined: Nov 2025
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C43 2020
Rattling sound when cold revs
The first time I start the car, it's cold. Then when it's in neutral/park I give it gas and around 2-3k rpm, when they drop down, I hear a rattling sound, but after 2-3min of warming up it's no longer audible. It's from the engine compartment on the driver's side.
I suspect the wastegate flaps.
I suspect the wastegate flaps.
Out Of Control!!
Joined: Apr 2019
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
the wastegate make sense but what I hear are the GDI injectors before ECU switches injection mode.
Wastegates would keep being noisy and not go quiet.
The fact your injectors do switch injection mode is a positive sign.
Wastegates would keep being noisy and not go quiet.
The fact your injectors do switch injection mode is a positive sign.
Thread Starter
Junior Member
Joined: Nov 2025
Posts: 37
Likes: 0
C43 2020
Out Of Control!!
Joined: Apr 2019
Posts: 12,003
Likes: 6,827
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
nothing's wrong
Definitely not bad injectors...
100% normal crickets until warmed up temps.
Your Bosch injectors will be bad when they start leaking high rail pressure during heat soaks.
Now they are working perfectly.
100% normal crickets until warmed up temps.
Your Bosch injectors will be bad when they start leaking high rail pressure during heat soaks.
Now they are working perfectly.
Last edited by CaliBenzDriver; Apr 11, 2026 at 06:00 PM.
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Thread Starter
Junior Member
Joined: Nov 2025
Posts: 37
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C43 2020
Here is new video, Only rattling when the engine is cold, only above 2k rpm
It seems to me that it has a fluctuating boost. Maybe that's normal. When accelerating in comfort, the boost shoots up, but then drops immediately, or fluctuates in general. No engine light or limp mode.
At full throttle = full constant boost
Without throttle = 0 boost
It seems to me that it has a fluctuating boost. Maybe that's normal. When accelerating in comfort, the boost shoots up, but then drops immediately, or fluctuates in general. No engine light or limp mode.
At full throttle = full constant boost
Without throttle = 0 boost
