If you are referring to an engine knock at about 1100 rpm under light load, I went through this with a 2017 Ridgeline. It reared its ugly head within the first thousand miles or so. It never got worse over 4 years and 25k miles but I was obsessed with it, often not using the radio so I could hear the engine. I thought maybe it was part of the timing gear like a loose tensioner or something like that but it did sound like it was coming from the lower end of the engine. I was very vocal about this on the Ridgeline forum posted videos and there was a video of a guy with an MDX that made the exact same noise so I knew I wasn't alone. I would even roll my window down when next to anything with the same engine when at a red light and listen to them pull off, it was driving me crazy. When the 3/36 was about to end I took it to the dealer to document and of course it was a waste of time and got the good old could not duplicate response.. This frustrated me and with the mushy brake pedal I was thinking of dumping the Ridgeline. The noise would happen every time on my slightly sloped driveway on a warm engine when I would pull off after opening the garage. I could brake torque the engine at 1100 RPM and it would be there every time on a warm engine.
When I got the Passport, on the drive home I pull it into the garage and what do you know, the exact same noise just much more subtle. Sorry, but it's a Normal characteristic of the engine. the direct injected earth dreams V6. My port injected Accord sounds so much better, no injector noise, no fuel pump noise, it's still a total gem. Since the noise only occurred in gear I now know it's not related to the transmission as the Ridgeline had the 6 speed and the Passport the 9 speed. I suggest you end your search for a reason because there is no cure for this one, it's just the resonance of the engine.