It's a 99 model E300. Used to be my mothers car, and I'm going to be buying it back.

It knocks when it's cold, but once it's warm it quiets down and sounds like a healthy 606. Our friend who has the car now replaced all 6 injectors on the car when 1 injector went bad, but oddly enough it still knocks until warm. The whole engine has been taken apart as well and the bottom end is not the problem.

It has to be fuel related, but I can't think of anything else. Please feel free to chime in with ideas, kind of at a loss.

Jake