Buzzing/rattling at low rpm

hzzz · 04-02-2021, 01:56 PM

My 2018 CPO m4 has a buzzing/metallic rattling only at around 1800 RPM, after the engine is hot. It does not appear at idle, but only appear when the engine is under load. The dealer checked exhaust and found no problem. Does anyone else have had a similar problem?

bsmf8x · 04-02-2021, 02:13 PM

Is it only in sport plus? The car should only be seeing very light throttle at 1800 rpm's. You got Dct or manual?

Giving the car heavy throttle especially a manual is going to lug the engine creating a vibrating feeling at a low rpm like 1800. Ive experienced this in other manual cars, my m4 is a Dct so I wouldn't know as I never give heavy throttle at 1800 rpm

kumkeet · 04-04-2021, 09:55 PM

yes. mine does that as well. I have tried searching in here. Probably exhaust valve flaps vibrating as i hear mine coming from there. So i just change my driving style. Heavy load, low RPM is generally not good for the car anyway

terreh · 04-05-2021, 06:22 AM

I get this too, at normal/cruising acceleration between just after 1,500rpm.

After a bit of searching it seems more likely a wastegate rattle than the exhaust valves rattling.

Sounds like a common problem, but doesn't really seem to be an easy fix for it.

Fahrzeugtechnik · 04-05-2021, 10:55 AM

Do you have a sound file ?

hzzz · 04-07-2021, 04:09 PM

It is in all throttle modes. Also the car is a DCT. I generally can avoid the problem by releasing the throttle a bit as it goes towards 1800 rpm so that it shifts up. After a bit searching indeed it could be more like a Wastegate problem...

It sounds exactly like this https://f80.bimmerpost.com/forums/sh....php?t=1657374

kumkeet · 04-08-2021, 02:00 AM

similar sound. But mine comes from the rear exhaust area. So I don't think it's wastegate.

Fahrzeugtechnik · 04-08-2021, 03:32 AM

Quote:

Originally Posted by hzzz

It is in all throttle modes. Also the car is a DCT. I generally can avoid the problem by releasing the throttle a bit as it goes towards 1800 rpm so that it shifts up. After a bit searching indeed it could be more like a Wastegate problem...

It sounds exactly like this https://f80.bimmerpost.com/forums/sh....php?t=1657374

This is the wastegate i think so

PandaxF82 · 06-19-2021, 02:10 AM

Any additional info or insight on this?

04-02-2021, 01:56 PM	#1
hzzz Registered 0 Rep 3 Posts Drives: 2018 M4 convertible Join Date: Dec 2020 Location: NJ iTrader: (0)	Buzzing/rattling at low rpm My 2018 CPO m4 has a buzzing/metallic rattling only at around 1800 RPM, after the engine is hot. It does not appear at idle, but only appear when the engine is under load. The dealer checked exhaust and found no problem. Does anyone else have had a similar problem?
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04-02-2021, 02:13 PM	#2
bsmf8x Lieutenant Colonel 777 Rep 1,636 Posts Drives: F82 Join Date: Jan 2020 Location: NY iTrader: (1)	Is it only in sport plus? The car should only be seeing very light throttle at 1800 rpm's. You got Dct or manual? Giving the car heavy throttle especially a manual is going to lug the engine creating a vibrating feeling at a low rpm like 1800. Ive experienced this in other manual cars, my m4 is a Dct so I wouldn't know as I never give heavy throttle at 1800 rpm
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04-04-2021, 09:55 PM	#3
kumkeet Private 45 Rep 85 Posts Drives: M3 F80 Dakar Yellow II Join Date: Jan 2019 Location: Singapore iTrader: (0)	yes. mine does that as well. I have tried searching in here. Probably exhaust valve flaps vibrating as i hear mine coming from there. So i just change my driving style. Heavy load, low RPM is generally not good for the car anyway
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04-05-2021, 06:22 AM	#4
terreh New Member 4 Rep 11 Posts Drives: 2016 F80 M3 Join Date: Apr 2020 Location: New Zealand iTrader: (0)	I get this too, at normal/cruising acceleration between just after 1,500rpm. After a bit of searching it seems more likely a wastegate rattle than the exhaust valves rattling. Sounds like a common problem, but doesn't really seem to be an easy fix for it.
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04-05-2021, 10:55 AM	#5
Fahrzeugtechnik New Member 9 Rep 7 Posts Drives: M4 Coupe Join Date: Oct 2020 Location: FFM iTrader: (0)	Do you have a sound file ?
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04-07-2021, 04:09 PM	#6
hzzz Registered 0 Rep 3 Posts Drives: 2018 M4 convertible Join Date: Dec 2020 Location: NJ iTrader: (0)	It is in all throttle modes. Also the car is a DCT. I generally can avoid the problem by releasing the throttle a bit as it goes towards 1800 rpm so that it shifts up. After a bit searching indeed it could be more like a Wastegate problem... It sounds exactly like this https://f80.bimmerpost.com/forums/sh....php?t=1657374 Last edited by hzzz; 04-07-2021 at 06:28 PM..
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04-08-2021, 02:00 AM	#7
kumkeet Private 45 Rep 85 Posts Drives: M3 F80 Dakar Yellow II Join Date: Jan 2019 Location: Singapore iTrader: (0)	similar sound. But mine comes from the rear exhaust area. So I don't think it's wastegate.
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06-19-2021, 02:10 AM	#9
PandaxF82 Private First Class 48 Rep 128 Posts Drives: 18 BMW M4 6MT Join Date: Apr 2019 Location: Los Angeles iTrader: (1) Garage List 2018 BMW M4 [0.00]	Any additional info or insight on this?
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