When do you know when the ignition coil is going out/bad? Also what are the common symtoms that are indicating that its bad? Thanks

98 LS non-vtec.

 

Besides no spark?

Perhaps codes - misfire..
Erratic failure (works, no work, works), seemingly no pattern - possibly worse when warm.

 

My car misfires at times. Drives normally but maybe 20-30 minutes into the drive it starts dieing out. Is there a way to check if its bad by taking it out. Like what signs should i be looking for on the coil itself?

 

If it's electronics, there's not much to see. If windings are shorted in the coil, you can sometimes see heat damage and charring - so it's more obvious.

Once in a while you'll take off the distributor cap to discover it's started arcing (perhaps too long since service, moisture got in, or the little graphite buttons fall apart) and the rotor and cap just need to be replaced.

How do things look inside? You have to pull the cap and rotor, then pull the cover so you can see the works underneath...