[JFray23]

Hey all, about 500 miles on my 24 M240i. Noticed on cold starts after car has sat overnight or for a few hours that upon starting the car, you can feel an uneveness in the idle and can feel subtle vibrations and shaking through the drivers seat. You can also hear an uneveness in the exhaust sound if outside the car. Once the RPM’s settle to normal, it appears to settle and idle smooth.

Just wondering if this is a characteristic of the B58 engine. On warm starts after driving and running in somewhere quick, the car idles smooth when I restart. Only seems to happen when engine has not run in awhile. Thanks for any feedback or insight.

[BimmerBenzorBentley]

Yup unfortunately the harsh idling is a known issue with the G42s, also the headlight condensation issue that seems to affect all G42s. And for me specifically my iDrive is stuck on an 11/2021 version and won't prompt an update. Overall displeased with my first BMW purchase, the dealerships seem incompetent as well which doesn't help.

[JFray23]

Originally Posted by BimmerBenzorBentley

Yup unfortunately the harsh idling is a known issue with the G42s, also the headlight condensation issue that seems to affect all G42s. And for me specifically my iDrive is stuck on an 11/2021 version and won't prompt an update. Overall displeased with my first BMW purchase, the dealerships seem incompetent as well which doesn't help.

Okay good to know. I’ve owned multiple new BMW’s but all my recent vehicles had the B48. I was surprised about the vibration and shakiness at start up but I can live with it if it’s a known issue.

[BimmerBenzorBentley]

Originally Posted by JFray23

Okay good to know. I’ve owned multiple new BMW’s but all my recent vehicles had the B48. I was surprised about the vibration and shakiness at start up but I can live with it if it’s a known issue.

Man this is BMW we're talking about, we shouldn't have to live with issues lol. But yea I have a B48 2022 230i and my car doesn't shake but it shouldn't regardless, feel bad for ya.

[Pentland]

Originally Posted by BimmerBenzorBentley

Yup unfortunately the harsh idling is a known issue with the G42s, also the headlight condensation issue that seems to affect all G42s. And for me specifically my iDrive is stuck on an 11/2021 version and won't prompt an update. Overall displeased with my first BMW purchase, the dealerships seem incompetent as well which doesn't help.

Really? Never heard of the idle issue on here.

It’s certainly not normal - back to the dealer to investigate.

[WilcoJunoHotel]

Originally Posted by JFray23

Hey all, about 500 miles on my 24 M240i. Noticed on cold starts after car has sat overnight or for a few hours that upon starting the car, you can feel an uneveness in the idle and can feel subtle vibrations and shaking through the drivers seat. You can also hear an uneveness in the exhaust sound if outside the car. Once the RPM’s settle to normal, it appears to settle and idle smooth.

Just wondering if this is a characteristic of the B58 engine. On warm starts after driving and running in somewhere quick, the car idles smooth when I restart. Only seems to happen when engine has not run in awhile. Thanks for any feedback or insight.

Mine has done it since new - almost 2K miles now. Barely perceptible on mine though - just a little lumpy idle for a minute or so then it smooths out. Only on cold starts when it has been sitting overnight. I am guessing it is the fuel injection system. When I take mine in for the first free oil change I will have them look at it.

[JFray23]

Originally Posted by WilcoJunoHotel

Mine has done it since new - almost 2K miles now. Barely perceptible on mine though - just a little lumpy idle for a minute or so then it smooths out. Only on cold starts when it has been sitting overnight. I am guessing it is the fuel injection system. When I take mine in for the first free oil change I will have them look at it.

Yep same on mine but I’m not going to stress it as it appears to be somewhat common. The RPM’s don’t fluctuate on the cold start but I can feel the unevenness in my seat until it warms up and then it completely evens out.

[RockCrusher]

Originally Posted by WilcoJunoHotel

Mine has done it since new - almost 2K miles now. Barely perceptible on mine though - just a little lumpy idle for a minute or so then it smooths out. Only on cold starts when it has been sitting overnight. I am guessing it is the fuel injection system. When I take mine in for the first free oil change I will have them look at it.

I notice a bit of engine roughness -- but nothing that has me thinking it is a problem -- upon/shortly after a cold start of my 230xi and M2.

I believe it is the engine reacting to an overly rich mixture done on purpose to supply excess fuel to the converters to get them to warm up quicker.

The engines smooth out as the elevated cold idle RPMs drop to near hot idle RPMs concurrent with the engine controller going closed loop mode and the overly rich mixture gives way to a leaner mixture.

My 2 BMWs are not the only engines to manifest this bit of roughness after a cold start. It has been common with engines as far back as I can recall. (In all from memory 17 engines from a 90hp VW TDi to a 707hp Hellcat.)

Now two times two different engines manifested enough roughness over and above what could be considered normal (and in one case the CEL came on and misfire error codes were logged) at cold start to have me suspect a problem.

One engine was in the the VW TDi. Long story short the coolant sensor was bad.

The other engine was in my 996 Turbo. I "fixed" the CEL/misfires upon shortly after a cold start by just cutting short how long I let the engine idle after a cold start. Oh, the engine never misfired or acted up at any other time.

Some time (years) later I found the cold misfires were no more. But I had not done any engine work to address these.

I'll add with at least two cars I know of: Hellcat, Scat Pack; lack of sufficient use had both cars manifest odd symptoms upon/after a cold start. No misfires, rough idle, but issues of an electronic nature. Car apps that hung when I tried to load them. Goofy LCD displays. And the more disturbing symptom was the Hellcat its +paddle would cause a *down shift* rather than an up shift. No CEL but shop foreman found several proprietary low voltage error codes. He applied several firmware updates and upon learning of low voltages I drove the car more often.

No more problems. (Oh I drove the Scat Pack more often too and no more problems.)

[JFray23]

Originally Posted by RockCrusher

I notice a bit of engine roughness — but nothing that has me thinking it is a problem — upon/shortly after a cold start of my 230xi and M2.

I believe it is the engine reacting to an overly rich mixture done on purpose to supply excess fuel to the converters to get them to warm up quicker.

The engines smooth out as the elevated cold idle RPMs drop to near hot idle RPMs concurrent with the engine controller going closed loop mode and the overly rich mixture gives way to a leaner mixture.

My 2 BMWs are not the only engines to manifest this bit of roughness after a cold start. It has been common with engines as far back as I can recall. (In all from memory 17 engines from a 90hp VW TDi to a 707hp Hellcat.)

Now two times two different engines manifested enough roughness over and above what could be considered normal (and in one case the CEL came on and misfire error codes were logged) at cold start to have me suspect a problem.

One engine was in the the VW TDi. Long story short the coolant sensor was bad.

The other engine was in my 996 Turbo. I "fixed" the CEL/misfires upon shortly after a cold start by just cutting short how long I let the engine idle after a cold start. Oh, the engine never misfired or acted up at any other time.

Some time (years) later I found the cold misfires were no more. But I had not done any engine work to address these.

I'll add with at least two cars I know of: Hellcat, Scat Pack; lack of sufficient use had both cars manifest odd symptoms upon/after a cold start. No misfires, rough idle, but issues of an electronic [...]

Thanks for the response. I didn’t think it was probably anything major as it just feels like a subtle rumble in my seat for about a minute and then completely smooth once the RPM settles to normal operating temp. Also if I shift into gear during that first minute and start driving the uneven feeling is gone.

[ninja_geezer]

yes same here done it since day one ,on initial cold start after being left overnight its like a misfire nearly soon goes ,drives as smooth as silk just like my last b58 did

[JFray23]

Originally Posted by ninja_geezer

yes same here done it since day one ,on initial cold start after being left overnight its like a misfire nearly soon goes ,drives as smooth as silk just like my last b58 did

Appreciate the confirmation. Definitely a blast to drive!!!