“When the engine is started in cold condition a tapping/knocking type noise can be heard for 2-6 seconds. After this time the noise will stop. If the engine cools down to a cold condition, and is again started, the noise may be heard again.
The new Variable Valve Timing (VVT) system is suspect to be the cause (bleeding down). This system is comprised of several components. These components have been improved to eliminate the noise concern. To repair the concern, please order the following new level parts.
BP6D-10-660C - (#) Oil Control Valve Cover
BP6D-14-420C - (##) Oil Control Valve
BP6D-12-4X0C - (###) Variable Valve Timing Actuator
Gaskets - Please refer to the parts EPC or Microfiche for related gaskets
(#) Oil Control Valve Cover - is mounted on top of the valve cover.
(##) Oil Control Valve - is inside the Oil Control Valve Cover.
(###) Variable Valve Timing Actuator - is part of the camshaft gear.”
That’s dated 2001, so later cars ought to have the new parts. But this certainly seems to be the noise you’re describing.