Congrats on your ATS.

If the car has the owners manual the proper fill for both coolant tanks is detailed in there, but when the car is cold the top tank should be full and the bottom tank should be filled to the line/marking on the side. And yes, you fill it via the small tube located rearward of the top tank. Hopefully the tank has not been bone dry for long. I would say it either was not filled correctly before, or there is potentially a leak somewhere.

Did the car misfire before you changed the plugs? What type did you change them out with, and what are they gapped to? These cars do tend to shake slightly and randomly at idle it seems, but if there is a misfire that is a different story.

 

i just noticed the tank being empty but the car hasnt ran warm or even hot at all. im going to refill it tomorrow and see how it goes.

the misfire is only on start up, like its searching, and i guess it could be a shake at idle cause it doesnt sputter or anything like a misfire, more just a random shake. ive not had time to take it to have someone pull up the live data yet. its basically running the same as before i changed the plugs, and i put in the denso race plugs from zzp. i dont remember the gap honestly, it was what was suggested. pretty much all the plugs came gapped at what i was recommended.

 

Did you ever find the issue to the sudden shakeing and low coolant level ?