Hello, I have a problem with my Z4 3.0si with the N52 engine and 265 HP fand was hoping to get some help here.
On cold starts, the idle speed is not stable. It is fluctuating quite a lot within a range of +/- 400 RPM.
This is happening already for a long time and is only on cold start and will go away after a short time (+/- 40 sec) when keeping it on idle. When starting, and then immediately go to drive and then keep the engine on idle, the idle is most of the time stable. When the car is not completely cold anymore, it runs perfect. I always use octane 98 fuel.
I already changed some parts to try to fix it. There are no error codes present in the car, also when reading out with BMW software.
I changed the following components not too long ago and didn't had effect on the car:
- 6 NGK spark plugs
- 6 Bosch coils
- 4 Bosch O2 sensors
- Fuel injectors tested and cleaned (passed the test)
- Fuel pressure regulator (including filter in the tank)
- 2 new original camshaftsensors
- cleaned both Vanos solenoids
- cleaned both Vanos filters
- checked oil filter housing for O-rings
- new starter
- new battery (Varta, 2020)
I was hoping someone here could point me in the right direction? Or share your solution if you had the same problem.
