Why do good coils go bad?

I have had a Bosch blue super coil since the car was new. I added electronic ignition a year ago. Friday, 103 miles from Vegas the motor quit. I bought a new coil in Barstow, 29.00 and no markings to know who manufactured it. The car now seems fine. Why would the coil go bad? Should I replace the new no name? Are there coils made to run with electronic ignition? Help if you can. Thanks!!

http://www.pertronix.com/support/tips/default.aspx#a2 follow this link to the Pertronix troubleshooting page. There is an issue with electronic ignition/points replacement modules and incorrect coil resistance. There are at least 2 different Bosch "Blue" coils. I do not know the make of your system, but most have a similar situation. Check this link http://www.ratwell.com/technical/BlueCoil.html for info om Blue coils, and the different kinds.

Most of the Bosch Blue Coils are made in the orient. Malaysia is one of the producing countries. These coils are notorious for failure.

Stick with the new coil, it's probably much better than the Bosch.

Big coils don't cry...

Back on subject, Your title is "Why do good coils go bad?"

Because they are no longer good...... As explained, they are made in the orient, when they were made in Germany, they were great, not too bad when they were made in Barzil. Piss poor now that they are made in the orient. Pertonix, Jacobs, and a host of other companies make good coils. Check to see if you need a ballast resistor when changing coils. Bosch has an internal ballast.

there are quite a few different 'blue' coils. make sure you buy the right one:
http://www.ratwell.com/technical/BlueCoil.html

When I was in college, a physics teacher told us how certain items should NEVER wear out - a condenser for instance. So for the next tune-up on my Chevy 327, I ignored the condenser and just replaced the points. Short time later car is dead, got towed in. One guess what was wrong? That was when I learned the difference between theory and real life empirical data.

In theory, there is no difference between practice and theory. In practice, there is!