I have an 02 Accord with the 2.3 F23A4 engine. The engine was quiet when I first got the car but about 30k miles later at around (190k) it started to sound like it was making a loud knocking noise when it was cold or at a certain rpm when letting off the throttle. I wasn't overly concerned about it as I always maintained the proper oil level. I was just going to keep an eye on it to see if it gets worse. The car now has 227k on it and it still makes the same noise maybe slightly worse. It's more noticeable in the cold weather than the summer. Also when it's really cold out and I start it the engine is quiet for a couple minutes then it starts to make the noise again. Is it possible for the engine to be knocking for almost 40k miles or is this probably piston slap? The valves were just adjusted and the sound didn't get better or worse.