This is the second time we have burned the top off the coil and the connection to the distributor cap on our 1990 Civic DX with a 1.5. The coil lasts approximately a year. Anybody have any ideas why this is happening?

 

Is your distributor missing any of the parts shown in the diagram? Are any of the distributor parts damaged (cracked or burnt)?

When was the last time you replaced the plugs, plug wires, and rotor? If any of these components malfunctions, the coil could blow.

Do you ever pull a plug wire or remove the distributor cap and then crank the engine?

 

Are you using OEM parts or aftermarket knockoffs? Also like Ron said, a bad or missing plug wire is hard on the coil. It will usually be an internal failure though. There's no reason for arcing / burning at the top unless the parts aren't fitting together properly.

 

Try to get an entire distributor assembly from a junk yard. Should be cheap, solve your problem, and be easy to find for that motor.

 

We replaced the original distributor with a brand new one. We put on new NGK wires and new NGK plugs. We had just put on a new Borg Warner cap and rotor.We're not positive the distributor was OEM as we bought it from an auto parts store and not the Honda dealer. We still have the original distributor that the shop mechanics replaced the burnt up coil in it. We put that one back in the car and are driving on it now. We were told there is something in the car that controls the voltage. Could this have something to do with it? We did everything that you recommended before we had the second coil burn up. For now the car is running fine. Hope it stays that way.

 

the ignition system control the voltage im pretty sure.

If you really serious about fixing your problem, please read this
http://www.familycar.com/CLASSROOM/ignition.htm

 

If you had that much excess voltage, you'd have many other problems too.

Make sure the contact point and spring are in place as shown in the drawing. There must be solid metal to metal contact throughout the connection from the coil tower to the metal bus in the cap. Not sure about a Borg Warner but clearly it is not OEM, those are "TEC" or Hitachi.