I've noticed an odd engine sound in my car for a few weeks. I'm not sure if this is new, or if it has been there all along and I'm just now noticing it. The motor has a higher pitched chirp/tick kind of sound, kind of a high frequency cricket type noise. It seems to vary with RPM and gets louder with throttle. I understand that direct injection can make some interesting noises, but was curious if anyone else had noticed this. Being unfamiliar with DI motors, I'm immediately paranoid that I'm hearing some sort of valvetrain issue.