I have one of those hard to diagnose engine noise issues. My '16 Pilot with 55K miles has developed a slight, but noticeable metallic sounding rattle when the car is stopped, like at an intersection. As soon as I step on the gas, it goes away. Starts to reoccur as I come to a stop. Dealer acknowledged hearing the sound and checked engine for valve noise, but said that wasn't it. No codes were tripped. He did update the tranny with latest flash download. Otherwise car had no issues to him. Sitting in the drivers seat rattle is very noticeable. If I open the hood with engine running, I hear nothing unusual from the front. But if I lean down by an open door or crawl under the vehicle with engine running I can clearly hear it coming from the back of the engine area ... or so it seems. I even poked all the aluminum heat shields and exhaust system to see if any of them were loose. All were tight. So I'm taking it back to the dealer Monday and asking him to get under the vehicle and check for the noise (oil pump, serpentine belt, tensioner, transmission, etc). I'm concerned because in a couple of weeks we head out for a 2,000 mile trip. I'm stumped. Any thoughts?