[tomking]

Originally Posted by Jason.MZW20

Could be piston slap, but that'd be an awfully extreme case. My 1GR sounds worst between 1200-2500rpm, then smooths out after that. Sounds similar to rod knock, but it's definitely piston slap. Mine occurs most when the engine is cold, under load or not, and reduces in intensity as the engine warms. It's still there, but not as audible.

Might be worth investigating whether or not the pistons have been replaced. Some pistons expand at different rates, and some just sound terrible from poor fit, like my 1GR.

I'm running 10W-40 to reduce the issue, but I can still hear it.

I've heard that some 3SGEs have a piston slap issue, but I don't remember where I heard that from, so take it with a grain of salt.

Sound like an expensive problem to fix.