Ravioliv

Hello all,
Seeking opinion and experience regarding some worrying symptoms on my car.
Not sure everything is linked but I would think so
Started 3 years ago with rough idle, misfire and high idle when hot.
Changed O2 sensor and MAF, fixed fuel vap valve that was stuck open, plugs, idle control valve.
All that improved the misfire and rough idle but not the high rpm when car is hot...
Engine runs like it has an air leak ( but I checked and there is none )
Checked the fuel pressure membrane above the engine and vacuum is OK so ruled that out
Recently changed the cylinder head temp sensor also...

Now the findings and worrying stuff
When I disconnect the idle control valve, *idle speed goes to normal.

Second symptom is that I believe there is something wrong with crankcase ventilation or oil circuit....that I kind of left aside until now as car runs fine.
Basically I have a significant amount of blow by that comes out from the dipstick when pulling it off when hot ( a bit like a kettle )
When adjusting the oil level after oil change yesterday this is where I got really worried as increasing the rev to 3000 to reach thermostat opening and read the level, then some oil flow back from the filler neck ( cap was removed as I was topping it up )
This messed up the engine bay indeed.... as I was on the gas pedal I do not know if the flow back happened when reving engine or when I backed off the throttle....
But in more than 10 years with the cars and doing all oil changes myself I never experienced that before...
Engine was rebuilt entirely 15000km ago

I am now wondering what could be wrong with the oil circuit and if my idle issue could be related to crankcase pressure building up in the oil tank and going to the intake through the ICV....
I have looked inside the intake and it is a bit oily but I would say not unusually....
I cannot assess oil consumption because I don t drive a lot and with the amount of oil in the engine it is hard to say....
I am scared by something like broken piston ring.....but car runs fine and does not have blue exhaust...

I will take appointment with porsche guru but any feedback is welcome...

cjoenck

This maybe too simple but start with basics:
- Oil level is measured with engine at operating temperature on level surface with engine at idle (not at 3,000 rpm) with dipstick. The gauge can be unreliable.
- Who did the last oil change? Is there a chance of a major overfill? An oil change required about 10 quarts. Total oil capacity is about 12 quarts but there will be about 2 left in the oil cooler, line, etc. - give or take a little. If someone put in 12 quarts, you are about 2 over.

Ravioliv

hello
thanks for comment
for oil level measurement indeed it should be at idle to have the oil back in tank. But to reach sufficient temperature I was reving it up
I always did that and I can t remember having back flow at the filler neck in 10years of owner ship…

regarding last oil change it was done the day before the backflow incident , by me and the engine received 8litres before the top up and I had refilled 0.5l I would say when it happens
So for me it cannot be an excess of oil….
+ there is the blow by at the dip stick