Great article. Just wish something would be made available to explain the oil pump in detail. *NM*

Came across this document online. Page 3; paragraph 5; first sentence. The variable pitch might be a feature ("electronic control" ) of every 9A1 motor. It doesn't account for the 1 psi I've observed when Auto Stop-Start is engaged and the engine is off. Could the oil pump have an electronically controlled clutch and be spun by a small electric motor in this case?
OilPumpOperation
Going to the link ought to cause the PDF to download to your device.

Please note the link it contains no longer works.



Edited 3 time(s). Last edit at 10/22/2018 12:34AM by Laz. (view changes)

I found this article from the North New Jersey PCA club. In the 3rd paragraph, it says the oil pump drive runs off the front of the crankshaft. In the 4th paragraph, it says the 9A1 engine has 4 scavenger pumps and the oil pressure is controlled via the DME. Does this mean there's some sort of electronically controlled clutch to control oil pressure? I know that oil pressure seems to stay fairly constant during different engine speeds and temperatures. Normally, you'd expect the oil pressure, when cold, would be much higher than when it gets hot. The only time the oil pressure seems to rise significantly is during hard acceleration.

As you said, it's hard to understand that there could be 1 psi of oil pressure if the engine is stopped under the stop/start system if there's no electric pump to keep up the pressure.

[nnjr-pca.com]

...pressure is variable, based on engine torque demand. The amount of pressure is controlled by the DME. There is no clutch. The pump is variable displacement with the displacement adjusted under DME control to cause the pump to produce the pressure desired. The pump defaults to full displacement and thus full oil pressure -- based on oil temperature and engine speed -- unless this is overridden by the DME.

Techs told me that at first it was a bit discerning to when driving a Porsche so equipped to when accelerating the car and using higher revs seeing the oil pressure shoot up -- like "normal" -- but to then see the oil pressure fall which is very much unlike "normal".

As for the presence of oil pressure with the engine off due to engine stop/start feature being active my info is this is provided by a small auxiliary electrically driven oil pump which supplies just enough oil to maintain a small positive oil pressure to primarily the main and rod bearings though of course the entire oil system is pressurized as the oil pressure gauge obtains its pressure reading from very far away from the oil pump from one of the cam shaft covers.

(A Porsche engine having an auxiliary oil pump is not new. My 2003 996 Turbo engine had a small engine driven oil pump specifically to supply oil to the turbos.)

Minus 40 degrees... Is that Fahrenheit or Celsius?