[mbnjp]

2021 M240i noise on up shift @ low rpm

Hoping this is an okay place to look for help.

Purchased this car (2021 M240i) last year CPO @ 6k miles. currently at 17k miles.

My car for the past few thousand miles has been making this noise which I would describe as a grind when starting and shifting up (and sometimes, but not every time shifting down) at low rpm. The sound is more noticeable with the windows down, but I can still hear it with them up. It sounds like it’s coming from under the car, but i’m unsure. I recorded a video that hopefully can give more insight.

In the video you can hear the sound on start up, and when driving through a parking struct when accelerating and approaching 1500 rpms the car will shift gears and the noise is present.

This video does not capture the noise on downshift, which ?sometimes? does occur.

I’ve been to the dealer over this a few thousand miles ago and they claimed to not find any issues. The noise has since gotten louder in my opinion.

If this isn’t the correct place to post this, I would love a recommendation.

Thanks in advance for any help!

https://youtube.com/shorts/c0m30JlDRpY?feature=share

[TrboMike]

Mine was more of a squeak and rattle than what I heard in your video. But I'd bet its your muffler flap not closing all the way. The car flutters it during cold starts and during a shift no matter what mode you are in (sport, normal eco). And then keeps it closed unless you are in sport or cruising. But in any mode it will flutter it during a shift to make the turbo not lag for the shift.

To test: Start the car and put it into sport mode. Look at your left exhaust with a flashlight and down into the pipe to the butterfly valve inside. It will stay closed during warm up if the engine is dead cold but it should open soon, or right away if the engine is warm. Once the valve is open, look at the outside of the exhaust where the motor and round clip is that controls the valve. There is a wire and harness on the motor, unplug it. Now the valve cant close. Go for a drive, see if the problem goes away. Let the car cool to dead cold, start it with the motor unplugged and see if the noise is still there. If the valve is not opening when you go to Normal or Eco, or not opening when you go to Sport, see if the clip between motor and valve is missing. If it is your valve is free balling and flapping around during high exhaust blast (cold start, shift). If the valve is now open and the noise is gone:
-the valve's bearing is clogged with carbon, spray cleaner on the outside by the clip and down the pipe (with engine cold) and work the valve open and closed
-motor bad, buy new motor (its held in with two or three bolts, easy)
-clip between motor and valve is broken, bent, or fell off. Replace clip or remove bent one and bend it back to proper tension between motor and valve

[TrboMike]

https://www.2addicts.com/forums/show....php?t=1848889

[Dvtchmxn]

Originally Posted by TrboMike

Mine was more of a squeak and rattle than what I heard in your video. But I'd bet its your muffler flap not closing all the way. The car flutters it during cold starts and during a shift no matter what mode you are in (sport, normal eco). And then keeps it closed unless you are in sport or cruising. But in any mode it will flutter it during a shift to make the turbo not lag for the shift.

To test: Start the car and put it into sport mode. Look at your left exhaust with a flashlight and down into the pipe to the butterfly valve inside. It will stay closed during warm up if the engine is dead cold but it should open soon, or right away if the engine is warm. Once the valve is open, look at the outside of the exhaust where the motor and round clip is that controls the valve. There is a wire and harness on the motor, unplug it. Now the valve cant close. Go for a drive, see if the problem goes away. Let the car cool to dead cold, start it with the motor unplugged and see if the noise is still there. If the valve is not opening when you go to Normal or Eco, or not opening when you go to Sport, see if the clip between motor and valve is missing. If it is your valve is free balling and flapping around during high exhaust blast (cold start, shift). If the valve is now open and the noise is gone:
-the valve's bearing is clogged with carbon, spray cleaner on the outside by the clip and down the pipe (with engine cold) and work the valve open and closed
-motor bad, buy new motor (its held in with two or three bolts, easy)
-clip between motor and valve is broken, bent, or fell off. Replace clip or remove bent one and bend it back to proper tension between motor and valve

so Im in the same situation although my creak only happens when the car is in sport mode and not in comfort. any advice?

[TrboMike]

Sounds like the muffler bypass butterfly problem I described. My advice is to do the lengthy explanation I already gave on how to see if thats what it is for you.