2010 Evo X GSR all stock except for a Cosworth drop in. I've noticed over the past few months that after driving for 15 or 20 min I hear a somewhat faint, slow, steady knocking sound that seems like it's coming from the engine bay when I'm at low rpms. Probably 1-2k, usually when I'm parking or pulling into a lot. I never hear it at start up. I've tried recording it but it's just too soft to get picked up by the mic on my phone.

Could this be engine knock? Can you hear that while driving?

 

Hey man, after like 10 years did you ever figure out what it was? I been having exactly the same problem. Only after 10 to 15 mins i hear it on low 1k-2k rpms just passing right after 2k it goes away. But mine its pretty loud very noticeable. I cant find anything else that could help me solve it else wheres. Would really appreciate if you could tell me what you did how you fixed it or you just sold the car what did you.do?

 

Check your oil. Is there any copper or silver dust.

 

not on mine but i found out the problem. Spark plugs were gapped wrong. Regapped them and problem fixed