[vasillalov]

For all of you who are experiencing idle stumbles, try Stabil ethanol stabilizer. Get the Marine one as its a higher concentration. Use 1oz per 10 gallons of fuel.

I have been using this additive in my N54 for over 8 years now and I've not needed to replace a single fuel injector in my N54 anymore. It truly works amazing. Prior to that, I was replacing one or two fuel injectors every spring.

[Shaneartistry]

Originally Posted by vasillalov

For all of you who are experiencing idle stumbles, try Stabil ethanol stabilizer. Get the Marine one as its a higher concentration. Use 1oz per 10 gallons of fuel.

I have been using this additive in my N54 for over 8 years now and I've not needed to replace a single fuel injector in my N54 anymore. It truly works amazing. Prior to that, I was replacing one or two fuel injectors every spring.

How often do you use it? Every fill up?

[Race_Doc11]

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

Originally Posted by Shaneartistry

Looking like I have the same issue with a faulty fuel injector as well. I have an appointment on the 12th. Most notable symptom is long crank after the engine is warm, almost like the car doesn’t want to start. Sometimes strong gasoline smell as well after the long crank. I’ve noticed “bouncy” rpm as well, but initially thought it was just how the M3 was. Now I’m wondering if it’s related to a bad fuel injector.

[Shaneartistry]

Originally Posted by Race_Doc11

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

Is yours manual or auto?

My long crank issue went away oddly enough. When the engine is warm instead of long cranks, sometimes it’ll start with a stumble, if that makes sense.

I don’t know if I had a bad batch of fuel or what with the long cranks. I’ve always used 93 octane.

I still have weird rpm jitters when the engine is cold and at times feel like the vehicle will stall when I put it in N coming up to a stop — almost like the rpm dips a little too low.

I’m planning on using some sea foam to see if it helps.

[Race_Doc11]

Automatic. The long crank is very random at all temp cold or hot. The bouncy idle all the times but sometimes feels worse as if the car will stall.

Originally Posted by Shaneartistry

Is yours manual or auto?

My long crank issue went away oddly enough. When the engine is warm instead of long cranks, sometimes it’ll start with a stumble, if that makes sense.

I don’t know if I had a bad batch of fuel or what with the long cranks. I’ve always used 93 octane.

I still have weird rpm jitters when the engine is cold and at times feel like the vehicle will stall when I put it in N coming up to a stop — almost like the rpm dips a little too low.

I’m planning on using some sea foam to see if it helps.

[vasillalov]

Originally Posted by Shaneartistry

How often do you use it? Every fill up?

Yes, every fill up.

[Shaneartistry]

Originally Posted by vasillalov

Yes, every fill up.

Thanks. Do you add it before or after you fill up?

[vasillalov]

Originally Posted by Shaneartistry

Thanks. Do you add it before or after you fill up?

Before adding fuel, add 1oz per 10 gal. If you go over or under, no big deal.

[Race_Doc11]

The car is back from the dealer and as I expected they could not find any faults. They blamed the digital RPM indicator sensitivity for the bouncy idle which I respectfully disagreed because I feel it sometimes while stopping at red lights. The long crank didn’t happen in the last 2 weeks but still it is definitely longer than any M car I have ever owned. It seems to me sometimes as if the car is not recognizing that the key is inside

[dmanb2b]

Resting idle fluctuation on a s58 is completely normal, even after it's fully warmed up. Cooling system is extremely efficient and dme is doing it's best to keep the car warmed up at idle. My F97 has been doing this since new...especially noticable when filling the car up and it's sitting there idling in sport mode.

[anakratis]

Idle quality is crap, especially on cold starts when the oil hasn't reached nominal temp. You can hear/feel shudders or knocking occasionally which almost sounds like a misfire. Once car is warm and the gauge is sitting just under 1k RPM, no issues.

[harperium]

2.5 years of my X3M, and the idle has always been twitchy. It’s not rough by any means. But the needle is not what I would describe as steady.

[GolfR17]

Doesn’t feel rough, but see little fluctuations warm or cold at idle. Have had for over a year. Noticed the same thing on the F90 I had before. Always assumed normal.

[BMWnation]

These newer generation cars are much more sensitive given the tech/sensors monitoring a lot of parameters.

Have you all checked for codes? You would be surprise to see the car does throw codes, but it does not throw a CEL. it’s a bit weird.

Check for codes and LMK what you find…

[vasillalov]

Originally Posted by Shaneartistry

How often do you use it? Every fill up?

Yes, every fill up.

[yousefnjr]

After a couple years and ~10k miles of perfectly smooth idling, I am loathe to report that my baby has started to shudder and have the RPMs jump. I’m inclined to think it’s not normal seeing as how it just started. No codes or anything, and runs fine under load, but def feels like a miss at idle. Might try swapping plugs soon. Usually run an E55 tune, but still doing it with a tank of (crappy) California 91.

[SwankPeRFection]

Those of you with wonky idle, do you drive your car hard often (like redline it a couple of gears) or do you just drive around all civilized? Also, platinum plugs, especially ones geared towards a colder range due to a boosted engine, can foul up a little if you don’t ever just ring it out every once in a while. Iridiums will not be as susceptible to this issue if you change to them. (Not sure it stocks are plat or irid.) Additionally, DI engines will also form much more deposits on the intake valves if they don’t have secondary injectors on the intake plenum, when you constantly baby the engine. That too will lead to a slightly lumpy idle. If you’ve been babying it for a long time, go for a few harder drives for the next couple of hundred miles and see how things change after.

[yousefnjr]

Originally Posted by yousefnjr

After a couple years and ~10k miles of perfectly smooth idling, I am loathe to report that my baby has started to shudder and have the RPMs jump. I’m inclined to think it’s not normal seeing as how it just started. No codes or anything, and runs fine under load, but def feels like a miss at idle. Might try swapping plugs soon. Usually run an E55 tune, but still doing it with a tank of (crappy) California 91.

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

[vasillalov]

Stabil won't fix idle issues. Stabil prevents degradation of ethanol blended fuels and thus acts ss a preventative measure, not a repair. I just wanted to make sure that's clearly understood.

[KevinGS]

Originally Posted by harperium

2.5 years of my X3M, and the idle has always been twitchy. It’s not rough by any means. But the needle is not what I would describe as steady.

and I like it

rough idle when cold = race car

The car is already smooth enough, so I'm OK with an uneven idle with a cold start, complete with some strange noises. Mine has been doing it from Day One, but it's never affected the drivability.

[BEAR-AvHistory]

20,000+ miles good idle so far.

[bmagic1771]

Wanted to chime in here for any future readers. I had a F80 with the previous gen S55 and had that idle all the time. Drove it for 30k+ miles and never had issues. Now with my current G82 on the S58, it still runs like that.

I just chopped it up to BMW M quality! It is totally normal as well from what I can tell. Could just be because of a low RPM idle to reduce emissions, who knows.