- Jan 6, 2019
- 335i E92 DCT
But it is reading 1 bar when the engine is off. And it is not reducing the 1 bar when reading at operating temp.I looked into this further, this is normal operation and values above atmospheric pressure are correct. Pressure will read ambient until oil pressure exceeds ambient pressure. This is exactly how the system functions on the N/S55. Here's a log from my 2017 M2 where poel_w is the oil pressure. With the engine off oil pressure remains close to ambient, while cranking the pressure increases past ambient. If you are looking to use our kit to verify oil pressure is primed (after say a rebuild) then just ensure it increases while cranking (this applies to stock N/S55's as well since they operate in the same way). BMW states the minimum oil pressure for the N54 at idle (fully warmed up) is 1.5 bar or 21.75 psi and 4 - 6 bar at higher RPM (again, fully warmed up).
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Or actual ambient pressure which may vary. It is no substracted as it should.
An oil pressure sensor is supposed to show absolute pressure. Most users will not know that ambient is not substracted.