When the valve idles, it will clank, and when you add a little throttle, it will not ring. What happened?

The abnormal sound of this problem usually appears in the valve or piston, which is caused by excessive clearance or carbon deposition, but it needs to be checked in detail. Each cylinder may be

fuel nozzle

Disconnect in turn to determine which cylinder has the problem, which may require disassembly of the engine pair.

Valve clearance

Where's the piston

carbon build-up

And the clearance between the piston and the connecting rod.