[BKLNGRAY_G80]

Originally Posted by yousefnjr

Following up on this. I ordered some new plugs (OEM NGK) and also some Stabil Ethanol treatment stuff. I tried the Stabil first and it didn’t make any difference. Then I imstalled the new plugs (gapped to 0.022”) and that seems to have done the trick. I’ve only gone on a single 30 minute drive but I am ready to declare victory. Idle is smooth as glass again and not a single misfire, shudder, or dip in revs. Car has just under 10k miles. Plugs that came out don’t look terrible to me.

Ready to have some ethanol back in the tank now, this thing feels sloooow

Did the spark plug swap continue to provide a smooth idle? My '24 M3 started developing the rough idle about 50-100 miles ago (only 550 miles on the car so far, but the hunting idle and misfire-ish shake was easily noticeable). Doesn't do it when the car is warming up (idle RPM was higher too, I think), only shakes when the car is already warmed up.

[yousefnjr]

Originally Posted by BKLNGRAY_G80

Did the spark plug swap continue to provide a smooth idle? My '24 M3 started developing the rough idle about 50-100 miles ago (only 550 miles on the car so far, but the hunting idle and misfire-ish shake was easily noticeable). Doesn't do it when the car is warming up (idle RPM was higher too, I think), only shakes when the car is already warmed up.

Yep, still smooth as butter. Not a single stumble since.

[Race_Doc11]

Same here the car has a rough idle from new and sometimes it dips as if it will stall when it’s completely warmed up. The car now has 14k miles. The dealer said it is normal but I’m not convinced.

[Lucky1]

Originally Posted by Forzanerazzurri

You guys should try an E46 M3 if you're sensitive to rough idling.

Man both S65 and S55 sound like diesels to me on a cold start, idle and 1st gear drive off. Nothing luxurious or smooth about that at all. Why can’t they be N52 quiet 😫

[MarkyB656]

Originally Posted by Race_Doc11

2023 M4 with 3000 miles and I have the same issue since new. The car is 100% stock.

same with me, it's normal with the S58. lumpy cams probably.

[TheRamon]

IMHO All cars do not have a perfectly stable idle. That’s the nature of a combustion engine, where idling is probably one of the hardest things to get right. BMW did a great job hiding it, for example on my G30 5 series. The (digital) needle did not move an inch.

There was a way to “trick” the system though. When rolling, flick the gearbox into neutral. If you had some speed, the needle and the idling wasn’t masked, and you’d see it jump or wiggle. When coming to a standstill, the needle would magically “align” and stay put.

Now, with my ID7 G80, the needle seems to wiggle even at a standstill. And I love them for that, because there’s no masking going on. Only real data. I can understand though when a lot of owners have their doubts that they would re-enable the masking part on ID8 vehicles just to have them calmed down.

[Mike02z]

I’m guessing most of you guys have not owned a cammed car? This one was not mine but had 2015 LS3 cammed Corvette that sounded identical

https://youtu.be/-u8ISIsg9F4?si=cx3G_cHbc1dK4DeX

You were lucky if you could get it to idle at all when Cold 😉

[Needsdecaf]

Originally Posted by Lucky1

Man both S65 and S55 sound like diesels to me on a cold start, idle and 1st gear drive off. Nothing luxurious or smooth about that at all. Why can’t they be N52 quiet ��

The HPFP is right on top of the engine. I don’t think they did much to quiet the fuel system noise down.

Actually, I forgot, there are TWO Hpfp’s. And they operate up to 5,000 psi!

https://bmwtechinfo.bmwgroup.com/tec...8%20Engine.pdf

You can see on page 26 they are mounted right on top of the cylinder head cover.

[Needsdecaf]

lol, the HPFP's are just sitting right there.

[SwankPeRFection]

Originally Posted by Mike02z

I’m guessing most of you guys have not owned a cammed car? This one was not mine but had 2015 LS3 cammed Corvette that sounded identical

https://youtu.be/-u8ISIsg9F4?si=cx3G_cHbc1dK4DeX

You were lucky if you could get it to idle at all when Cold 😉

Old cars didn’t have very good cold idle enrichment control from higher RPM and fuel enrichment, even if they were fuel injected. Modern engine management is very good at that but the combustion process is still an explosion… a controlled one, but still an explosion. Throw any variables at it like shitty plug gapping or a leaking injector and it’ll be anything but smooth. Firing order and cylinder layout play a roll too, but for the most part, these engines should be smooth. It should be common knowledge by now that if your gap is too large, it’ll idle a bit rough or if you’ve got a leaking injector the same thing. Both of these issues can be identified by easily pulling the plugs and looking at them. You find a dark one and that cylinder is running too rich for some reason. If they’re all proper looking, then close up the gap a little and it’ll smooth out and will also minimize the chance of misfires up top too on the rev range.

[sna66]

Originally Posted by yousefnjr

Yep, still smooth as butter. Not a single stumble since.

Is everyone just going to ignore that we have a solution here? I think its a big deal if a simple spark plug chnage fixes this issue. has anyone else tried the NGKs with positive results??

[SwankPeRFection]

Originally Posted by sna66

Is everyone just going to ignore that we have a solution here? I think its a big deal if a simple spark plug chnage fixes this issue. has anyone else tried the NGKs with positive results??

It’s the gap that’s important. Gap them down.

[yousefnjr]

Originally Posted by sna66

Is everyone just going to ignore that we have a solution here? I think its a big deal if a simple spark plug chnage fixes this issue. has anyone else tried the NGKs with positive results??

I would guess there’s maybe more than one thing going on, but yeah worth a shot for sure. It’s like $100 and an hour of work

[kgelfen360]

I have b58 in G05 and it idles much smoother then s58 and I am not talking about just digital needle. It feels very smooth compared to s58 at a red light.

[sna66]

Originally Posted by kgelfen360

I have b58 in G05 and it idles much smoother then s58 and I am not talking about just digital needle. It feels very smooth compared to s58 at a red light.

Yes, my wife’s g01 with the little 4 banger has extremely smooth idle

[kgelfen360]

Originally Posted by sna66

Yes, my wife’s g01 with the little 4 banger has extremely smooth idle

Are u saying b58 is a little 4 banger?

[sna66]

No she has an x3 with the b48, it’s an inline 4

[yousefnjr]

I’m here waiting for my kid to finish softball practice and recorded this very uneventful clip for you folks. This is what I would call “normal.” No long crank, no stumbles, just a smooth idle. The needle moves maybe a pixel and no vibrations can be felt. Anything rougher than this (and certainly misfires) may be common, but I don’t think it’s normal or by design

Car has catless DP, CAI and E55 tune if that matters. Idle was smooth when still stock too.

[RJC-1]

This sounds like a lean mis, I had a new 95 M3 back in the day (great little car) that did what is being described here.

[Znomorph4theWin]

It’s an inline 6 which has perfect primary and secondary balance. There really should really be no rough idle once it’s warmed up.

Mines butter smooth. At a light, I occasionally have to check the tach to see if the engine is actually running.

[SwankPeRFection]

Originally Posted by yousefnjr

I’m here waiting for my kid to finish softball practice and recorded this very uneventful clip for you folks.

A bit of a tangent, but I hope you only were idling it just to shoot that video and you don’t have a habit of sitting there parked idling the engine and using the A/C waiting on those practices to finish. That’s a surefire way to ruin an engine long term. Never make it a habit to idle engines for extended periods of time, it’s the worse thing you can do.

[RJC-1]

My wife reminded me both our new at the time Jag XKR’s (12&13) also had a lean mis. Our newer MB’s nor BMW’s with 8’s or 6’s have this issue., As the earlier poster wrote you can’t even tell the engines are running at idle.