S55 idle smoothness?

agent_orange · 02-16-2022, 03:37 PM

When stopped in traffic, the idle on my '21 M2C seems to be a bit uneven/lopey, and very slightly shakes the car.
Car has only 3,800km and first noticed this a while ago with only a few hundred km.
Stock tune, stock downpipes, stock exhaust, stock airboxes.
ISTA+ doesn't show any misfire codes or any other engine-related codes.

This is my first S55/N55 car so nothing else to compare it to.
I also have a diesel N57 which makes more idle vibration, but at least that is perfectly even and consistent.

Question: Is this normal or not?

I'd like to get an idea of whether this is normal or not before starting to do things like replace the spark plugs, having read about some folks on here who had a dud plug from new.

stefan · 02-16-2022, 05:21 PM

Mines a little bit rough as well. Never gave it much thought.

Detoxified · 02-16-2022, 08:24 PM

Could be cam alignment issues. Check out this guy who took a video of the engine idle sound before and after getting it fixed by BMW.

He was stock and very low miles.

https://m.facebook.com/groups/s55tun...82835145949100

KevM2 · 02-16-2022, 09:32 PM

Quote:

Originally Posted by agent_orange

When stopped in traffic, the idle on my '21 M2C seems to be a bit uneven/lopey, and very slightly shakes the car.
Car has only 3,800km and first noticed this a while ago with only a few hundred km.
Stock tune, stock downpipes, stock exhaust, stock airboxes.
ISTA+ doesn't show any misfire codes or any other engine-related codes.

This is my first S55/N55 car so nothing else to compare it to.
I also have a diesel N57 which makes more idle vibration, but at least that is perfectly even and consistent.

Question: Is this normal or not?

I'd like to get an idea of whether this is normal or not before starting to do things like replace the spark plugs, having read about some folks on here who had a dud plug from new.

Does this happen only while the engine is still warming up or even when it's fully warmed up to operating temps? While cold it would be normal

KevinC · 02-16-2022, 09:45 PM

At 10k miles mine purrs like a kitten, always has.

scarygary · 02-17-2022, 09:35 AM

Is it like the fuel to the motor is pulsing? like rpms ranging 200-300 difference? Mine does it when its warming up, definitely more noticeable with aftermarket exhaust. I asked the service guy about it and he had the tech guy look at it, everything is normal is what they said. About 44k on the car.

agent_orange · 02-18-2022, 08:36 PM

It does this when fully warmed up to operating temp.
No rpm change on the tacho and no noticeable sound change but that isn't saying much with a stock exhaust and windows up.
So it's felt, not heard or seen. Can feel the engine rocking slightly in its mounts in a uneven way at idle.

02-16-2022, 03:37 PM	#1
agent_orange Private First Class 152 Rep 127 Posts Drives: 2014 F25 X3 30d, 2021 F87 M2C Join Date: Apr 2020 Location: Australia iTrader: (0)	S55 idle smoothness? When stopped in traffic, the idle on my '21 M2C seems to be a bit uneven/lopey, and very slightly shakes the car. Car has only 3,800km and first noticed this a while ago with only a few hundred km. Stock tune, stock downpipes, stock exhaust, stock airboxes. ISTA+ doesn't show any misfire codes or any other engine-related codes. This is my first S55/N55 car so nothing else to compare it to. I also have a diesel N57 which makes more idle vibration, but at least that is perfectly even and consistent. Question: Is this normal or not? I'd like to get an idea of whether this is normal or not before starting to do things like replace the spark plugs, having read about some folks on here who had a dud plug from new.
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02-16-2022, 05:21 PM	#2
stefan Brigadier General 2354 Rep 4,254 Posts Drives: M2 Comp Join Date: Feb 2008 Location: North iTrader: (2)	Mines a little bit rough as well. Never gave it much thought. __________________ ///M Power
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02-16-2022, 08:24 PM	#3
Detoxified Second Lieutenant 205 Rep 269 Posts Drives: M2C HS Join Date: Jun 2019 Location: SoCal iTrader: (1)	Could be cam alignment issues. Check out this guy who took a video of the engine idle sound before and after getting it fixed by BMW. He was stock and very low miles. https://m.facebook.com/groups/s55tun...82835145949100
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02-16-2022, 09:45 PM	#5
KevinC your average JAMF 3101 Rep 4,094 Posts Drives: '21 M2 Comp, '19 Golf R Join Date: Oct 2005 Location: Cochise County, AZ iTrader: (0) Garage List 2019 VW Golf R [0.00] 2021 BMW M2 Competi ... [0.00]	At 10k miles mine purrs like a kitten, always has. __________________ '21 M2 Comp '19 Golf R
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02-17-2022, 09:35 AM	#6
scarygary Private 47 Rep 89 Posts Drives: M2C Join Date: Mar 2021 Location: Houston iTrader: (0)	Is it like the fuel to the motor is pulsing? like rpms ranging 200-300 difference? Mine does it when its warming up, definitely more noticeable with aftermarket exhaust. I asked the service guy about it and he had the tech guy look at it, everything is normal is what they said. About 44k on the car.
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02-18-2022, 08:36 PM	#7
agent_orange Private First Class 152 Rep 127 Posts Drives: 2014 F25 X3 30d, 2021 F87 M2C Join Date: Apr 2020 Location: Australia iTrader: (0)	It does this when fully warmed up to operating temp. No rpm change on the tacho and no noticeable sound change but that isn't saying much with a stock exhaust and windows up. So it's felt, not heard or seen. Can feel the engine rocking slightly in its mounts in a uneven way at idle.
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