[Prala]

Hi,

does anyone know the problem with this engine speed fluctuation, its minimal, but where does it come from?
YouTube: https://youtu.be/IKXYZEw-_f8

[TunafishE93]

My guess would be miss with the little known.

[E92William]

Could very well be a vacuum leak. Do you happen to have inpa and a laptop or a way to scan the car for codes? Would be helpful

[meikster]

have had this sort of fluctuation happening in cold starts until warm, slight shaking but subsided once warm. This has been happening on my car for 2 years, no codes no lights, interested in this

[POBEP]

Originally Posted by meikster

have had this sort of fluctuation happening in cold starts until warm, slight shaking but subsided once warm. This has been happening on my car for 2 years, no codes no lights, interested in this

same here. no codes of any kind. would be good to know what is wrong.

In addition to the above, I have the following:

scenario 1
- travel in any gear (2+) at 2,000+ rpm
- while keeping in the same gear coast down to 1,300rpm
- apply constance medium acceleration
outcome: hesitation between 1,400 and 1,800rpm

scenario 2
- warm engine, ac on, outside temp 20C+
- transmission in D, stopped at the traffic light for 40+ seconds
outcome: brief idle drop to 400 rpm

[Prala]

Originally Posted by E92William

Could very well be a vacuum leak. Do you happen to have inpa and a laptop or a way to scan the car for codes? Would be helpful

Hi E92William, i've already made everything new except oil pan. No errors dropped! the engine did this problem before. I want to renew the oil pan gasket in the next months. Do you think it could be this gasket??

its very different on my engine: no problems on cold start, it only happens when the engine is warm. no major drops in rpm, only this one in the video.

[mousefarmer]

Spark plugs been replaced recently? Before the eccentric shaft sensor goes out I think it may fluctuate like this.

[Prala]

Eccentric shaft target angle and actual angle do not match.
https://youtu.be/zLVpa4653ys

[lowrydr310]

Originally Posted by meikster

have had this sort of fluctuation happening in cold starts until warm, slight shaking but subsided once warm. This has been happening on my car for 2 years, no codes no lights, interested in this

It could still be a minor air leak. It could be small enough such that the DME can compensate and not trigger any codes.

I had this RPM fluctuation occasionally on my 325i and it even happened on my 330i a few times, first happening with no codes present. Eventually the 325i started throwing DMTL codes for a minor leak, which turned out to be the common failure of the evap vent hose that runs from the fuel tank and charcoal canister up to the intake manifold. It rubs against the metal edge of an air conditioning line and eventually wears through. My 330i RPMs had fluctuated a few times while stopped or at idle, also with no codes. It was most apparent after first starting the car, and happened a few times after coming to a stop. Eventually I got a SES light with a lean code. I rigged up a homemade smoke machine and fogged the intake, which quickly revealed a cracked CCV hose. I should have replaced that since the plastic hose was snapped in half but again used the silicone tape until I could order a new part and it's been holding up fine so far.

[W4HG0N]

+1 on vacuum leak possibility

also had the issue on my n52 and changed my vanos solenoids since I past 100K, no codes thrown, maybe a quick clean to see if that changes anything and if it comes back you could be closer to the culprit