The Nissan Path

Hey all. I just purchased this Pathfinder and noticed yesterday a higherpitched engine noise at about 2200 RPMs. It doesn't happen until after driving for a couple minutes but then occurs on about every acceleration afterwards.
Can't pinpoint yet where exactly it is coming from, I have a couple ideas but wanted to see if any of you have had or heard of this issue as well. Suggestions / fixes?

Thanks

Dave

Couple of things to consider.

There is a Technical Service Bulletin out for the VIAS: NTB05-015b

2005 NISSAN PATHFINDER, FRONTIER; RATTLE NOISE FROM VIAS POWER VALVE ACTUATOR / INTAKE MANIFOLD COLLECTOR
There is a rattle noise coming from the Variable Induction Air Control System (VIAS) Power Valve Actuator /
Intake Manifold Collector at engine speeds around 2,200 RPM.


Also, it could be your timing chain tensioner. Would you describe the high pitched sound as a whine? Here's an example: http://www.youtube.com/watch?v=IAdR9XnazCo

Does it sound like a power steering whine? Sound follows engine RPM? If so it is probably secondary timing chain shoes.