I just purchased a 2013 Nissan Juke with 41k miles on it. The first week of ownership was promising but yesterday evening I was noticing a chattering/vibrating noise when under light throttle while driving around. I was able to reproduce it while parked with light throttle applied floating around 1150-1700 RPM. It only made this noise while very light throttle was applied and immediately responded to throttle input. It sounded so closely like an exhaust shield vibration. I checked exhaust and could not find any broken hangers, loose shields, downpipe shield and mount seemed nice and tight. It does NOT make this noise when the engine is cool, only after a good warmup.
I had my girlfriend hold the throttle for me while I poked around under the hood listening for the source. It sounds like it's coming from underneath the timing chain cover right under the top-front motor mount. I tried to "feel" for it but could not physically feel it, just can hear the chattery noise. The noise goes away after 1800 rpm or so. The engine otherwise runs very, very good.
I then jumped online to find the dreaded timing chain campaign. I called nissan corp today, they verified the car did go through a timing chain repair and a fuel delivery fix of some kind in 2014. I am now out of warranty by 2 months. I am having a salt lake dealership take a look at it on saturday and hoping nissan corp will decide to help me out if the chain needs replacement again. Nissan corp did say there is an extended warranty on the vehicle but only applies if I purchased from a verified/certified dealer, which I am sure I did not.
I have not yet tried to remove my serpentine belt and restart the motor for a bit to find out if it's a pulley on the tensioner or accessory failure.
Any help/input is appreciated and I will update you all with what comes next.