Rough Cold Start Idle, P0011 Code

[andrec12]

Hi guys, this is my first post here, and its for a very particular situation. I'll start off by mentioning that I did plenty of research on this forum (I have 12 tabs open w/ threads on similar topics) but I still need help.


Car: 2002 540i 6spd, 135k miles


PROBLEM: When starting the car cold, the idle doesn't jump to ~1000 rpm like it used to (during open loop). Instead, it reaches maybe 800 RPM, and rough shaking/vibration occurs (like it's misfiring). It only occurs for about 5 seconds, then the SES light comes on (code P0011) and the shaking disappears. The idle remains slightly lower than usual.
What's weird is that the car drives perfectly fine when above idle (I drive it hard, too). Power delivery is instantaneous, and it pulls strong all the way up to redline. Zero driveability issues whatsoever. For this reason, I erased the code just to see if it would come on again.


When I shut the car off after driving and start it again (after it's warm) the idle drops very low (to ~ 400 rpm) where it is clear the M62tu does not like to be (rough and shakey). But as soon as I turn the A/C on, the idle goes back up to ~600 rpm and everything is smooth again.


Regarding the P0011 code, it comes on every 2 starts after clearing the code (the ECU has to see the problem occur in 2 drive cycles).


I should mention that the code has appeared once before (months ago), then disappeared. I thought nothing of it at the time.


Items I've replaced 5k miles ago:
Both Vanos rebuilt
All chain guides replaced
M60 intake upgrade, which came along with new complete CCV system components and all the hose/pipe connections underneath the manifold
Cleaned the TB
Both cam sensors replaced
Basically anything you can replace when doing chain guides, I replaced
Also fuel injectors were professionally sonic cleaned/serviced with new o rings. New fuel filter.



With the engine on, I did an inspection of all vacuum hoses on top of/around the intake manifold. Felt for vacuum with my fingers, and listened with my Stahlwille stethescope. Nothing. No tears, everything is tight.


P0011 refers to cam timing bank one, but how can cam timing be off when the car drives perfectly? What tool do I need to read my cam adaptation values to verify they are within spec?


I am really puzzled. What system/component influences cold start idle, AND would trigger P0011? With brand new chain guides and rebuilt Vanos?? And no driveability issues?

I appreciate all the help and advice!!

[MIKYZZ4]

This code can be several things. Least likely but easier to eliminate first:

1)Cam position sensors...swap positions and see if the problem moves to the other bank.

2)Vanos solenoids...swap positions and see if problem moves to other bank.

[JimLev]

Your code is only one thing. The things MIKY mentioned would have different codes.
Your bank 1 trigger wheel is slightly off. There is a range that the trigger wheel has to be in (a few degrees) to be within the acceptable range the DME is looking for. When you start the engine the DME tests it, if it fails the vanos solenoids are shut off so your vanos are not functioning.
When your guides were changed the trigger wheel was possibly not set exactly right and now due to some ware of the guides the error has increased just enough to cause the code.
If you have INPA you can read the cam advance/retard.
Your static timing, crank to cams, should be fine as they should have been locked when the timing was done.
As long as the center section of the vanos was fully retarded when the center bolt was tightened the only thing left is the position of the trigger wheel.
Do you have tools and able to work on the engine?

And welcome to the forum.