My car had had what I THINK is a low vacuum condition. It doesn't throw any cel or any driveability issues.
BUT it WILL smoke when I give it gas for the 1st time after allowing it to idle past 30seconds aftet the engine is fully warmed up.
I put on a new valvecover amd gaskets , new vacuum and i snoke tested it and found no leaks. The engine does also have a new turbo and handful of other modifications and nothing has made either issue any better and the new turbo because of it going from 18psi to 23psi i have noticed it began smoking more.The car when 1st started WILL make correct vacuum at like -12hg but soon as i even blip the throttle it looses vacuum snd will only see maybe -3hg then.
am I correct in my assumption that my cylinder head more than likely has BAD valvestem seals ???
I am uploading videos now..
Any help is always much appreciated.

 

 

 

I cleaned my tips before i left and this is after a 600mile round trip.

 

The N18 has near zero vacuum at idle. It’s normal. Since the intake has variable lift and timing, during normal operation the throttle goes wide open, and uses the valve lift and timing to control air intake.

That being said, smoke after long idle usually mean bad PCV…

 

That would normally be my thinking as well, but he said he changed the valve cover. If it was consistent across that then probably not the issue.

So yeah, maybe valve guide seals? That or the turbo bearing, though in that case you'd see oil in the intake tube, I'd assume, and it sounds like changing the turbo already didn't make a difference.

How many miles on the car and what oil are you using? I don't have a very good idea how long N18 valve guide seals last. You might try a thicker oil, see if that helps? Castrol Edge Euro 5W-40 is a bit thicker if you're currently using 30wt: it's A3/B4 and BMW LL01 and would be acceptable for this engine.

 

I can’t find the reference, but there have been at least a few members in this forum that have used those aluminum valve covers and had issues with the PCV in them. The good part is that the covers can be torn down to check. I wouldn’t discount the valve stem seals, but I also wouldn’t dismiss the valve cover PCV…

 

I will try changing back to oem valvecover and try and see if I can see anything obvious on the valve guides.
The turbo has no oil in it or intake tract and the turbo has under 5k along with valvecover..
but hey , doesn't mean the aftermarket valvecover pcv hasn't failed , that'd sure be nice.

 

If you replace with the OEM cover, disassemble the aftermarket and check the condition of the gaskets and seals, and see if you can tell if any oil is traveling through the passages.