if your vehicle code is DBA L275 (x) the engine is KF-VE it is a DUAL VVT engine.
If you are using engine oil above 5W-30 grade the rattling is of timing chain.
check for PCV valve replace the part, change engine oil & oil filter. down grade to 0W-20 or 5W-30.
It may resolve the issue. JDM 660 engine new repair parts does not exist in Pakistan., you may have to live with the rattle noise.