F30 316i N13 - Unstable RPM during cold start

[malayanbimmer]

Can anyone tell me what could possible be causing my rpm to be unstable during cold starts?.

Whenever I start my car from cold, when the rpm drops to idle range, the rpm will bounce exactly 4 times (never more) every single time I start my car from a cold start. During this time, the car would vibrate really hard. However, once it stabilizes at idle rpm, this issue would not resurface. It would not even surface during warm starts, only when I start my car from cold. My mechanic believed it was related to the variable cam timing and suggested to replace the valve timing parts (i.e. camshaft adjust unit, timing chain, chain tensioner, timing guides). Having repaired those parts, the issue unfortunately continue to persist. ��

Has anyone come across this issue before, if so please advise as to what may be causing the issue. (see attached link for clarity)

https://youtu.be/3bbr__YPhW0

UPDATE: Managed to resolve the issue

Turns out the reason my rpm was unstable during cold start was due to a hole in my positive crankcase ventilation valve (PCV VALVE). Replacing it costed less than $5.

Special thanks to dworthy for attempting to resolve my issue, appreciate it.

20210207_152529.jpg

[dworthy]

Welcome to the Forum!

Yes the N-13 does have issues with timing chains, and if you are near 100k km would be worth considering. My son's car would fall flat on its face, a F-20 114i w/N-13 motor last year when it was cold. It wouldn't run properly, stall out or just not accelerate when cold. The dealership performed a update to the DME and that fixed the problem, I am glad that it was still under warranty.

So do you have any codes that you can post up, if so make sure to write them word for word.

[malayanbimmer]

Welcome to the Forum!

Yes the N-13 does have issues with timing chains, and if you are near 100k km would be worth considering. My son's car would fall flat on its face, a F-20 114i w/N-13 motor last year when it was cold. It wouldn't run properly, stall out or just not accelerate when cold. The dealership performed a update to the DME and that fixed the problem, I am glad that it was still under warranty.

So do you have any codes that you can post up, if so make sure to write them word for word.

Hi, thanks for your reply.

The car is not showing any fault codes at all. My mechanic has also updated the ECU which unfortunately did not resolve the issue.

[dworthy]

Next step will be for the tech to watch live data while you attempt to re-create the issue.