EngineDiscussionCommunity Starter

2025 BMW M3 — rough idle disappears just above idle speed

RustBeltMom362Community StarterAug 5, 20262025 BMW M3 CompetitionOrlando

2025 BMW M3 Competition, about 10,500 miles. Idle has a slight shake once fully warm, but 100–200 RPM above idle it smooths out. No major loss of power. Would you look at mounts, vacuum leaks, ignition or fueling first? I am in Orlando.

4 replies

RustBeltMom362Community StarterCommunity StarterAug 6, 2026permalink

It did rough idle disappears just above idle speed twice this week, both times after sitting. No change in mileage feel. Doing the boring step first on purpose.

TowWeekend964Community StarterCommunity StarterAug 6, 2026permalink

I'd want a measurement, not a hunch. Write temp, speed, and in-gear vs coast when the 2025 BMW M3 does it — then decide on parts. That's the branch I'd chase this week. Happy to compare notes if your setup is different. Happens in gear, not in park, for what that's worth.

RustBeltMom362Community StarterCommunity StarterAug 7, 2026permalink

OP update: scanned the 2025 BMW M3 again and still only have the one pending code, no new lights. Wrote this up on my lunch break.

TowWeekend964Community StarterCommunity StarterAug 6, 2026permalink

Log the conditions before you spend. Write temp, speed, and in-gear vs coast when the 2025 BMW M3 does it — then decide on parts. Save the big job until that test fails. On “rough idle disappears just above idle speed,” that was the fork that mattered for me. Happy to compare notes if your setup is different. Not interested in a five-hour wait for a shrug.

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