Every time when I started the cold engine in the morning I heard some rare noise came from the engine. Like all the FD's the rpm will first go up to about 3k for warming up purpose then slowly fall down to normal rpm range, but between this warming up process the Engine will become "shaky" along with some "da..da..da" noise (the rpm needle also became a little shaky) for about 1 min, after that everything will back to normal, the problem only occur during warm up. This problem already happen when my FD was stock so it don't have anything to do with my mods.........could it be spark plugs???

Any professional advise will be highly appreciated!

Thanks in advance,
Johnny

 

Mine does this too, seems its part of the warmup process.

Not 100% sure though.

 

I can think of one advantage of a shakey warmup, perhaps it helps loosen carbon ... I have no evidence to support this though... just a thought.

 

^

 

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/engine-noise-during-warm-up-please-help-643627/