Loud Rattle/Knocking at Startup

On startup this afternoon, there was a fairly loud ticking/rattling/knocking sound coming from the engine. Temps were in the 40s-ish, and was a cold start. The car has 40k miles and this issue has never happened before. Gave a very slight tap to the throttle and the ticking matched the slight bump in revs. Also there was a greater amount of smoke coming out of the tailpipe and a stronger smell than usual. No CEL. After about 45 seconds everything returned to normal. Car behaved like normal and power output was unchanged.

Another post by Dr. Webster identified a similar issue but didn't mention the smoke or smell:
https://www.mazdas247.com/forum/showthread.php?123822110-Loud-knock-ticking-noise-on-startup&highlight=rattle+startup

Thanks everyone for your input.

Loud injectors, nothing to worry about.