N52 knock at cold start

[Juggernaught5]

2006 3.0si, N52

This noise has been happening intermittently at am startups - disappears after about 10 minutes. Appears to be coming from the driver's side, mid-engine, and varies with engine speed.

It's not the lifter tick that's also common - I have that occasionally as well.

The dreaded vanos rattle? DISA Valve?

[garz747]

The fuel injectors can be quite noisy with that engine- hopefully thats all it is,,,

[Sergio19]

Possibly piston slap.

[DerE85Fahrer]

Mine makes exactly the same noise at every cold start. I have a 2006 3.0i. It only starts once the engine slows down to normal idle speed, and it goes away as soon as I begin driving. If the engine is warm there is no knocking. The noise is worse if the car has been sitting for a week, and better if I drive it fairly hard for several days in a row. Anyone else have any ideas as to what it could be? I have been considering replacing the injectors as a preventative maintenance item, as they are original and I have 154k miles.

[Juggernaught5]

The car is going into the shop tomorrow for a climate control module replacement, and I'm going to ask about it then. I'll provide an update once I know more. Even when this noise goes away, I am hearing a bit of a rattle-like sound if I'm driving and let off of the throttle. I'm thinking the DISA valve, although I thought the issue with these was solved by my car's July 2006 production date.