Hey y’all I’m fairly new to the z community as I picked my z up just a couple months ago. I’ve been trying to diagnose an issue and I think I found it when my coil exploded in front of me. The po bypassed the ballast resistor and now I’m trying to replace the coil. I would be ok with an internal resistor but does the primary and secondary resistance change or is it the same spec? I can’t seem to find any at local auto part stores so what should I order?

What year Z and is the ignition system the factory stock parts or has it been modified?  Primary resistance is your main concern.  Welcome.  Most people don't get exploding parts to help them diagnose a problem.

13 minutes ago, Zed Head said:

What year Z and is the ignition system the factory stock parts or has it been modified?  Primary resistance is your main concern.  Welcome.  Most people don't get exploding parts to help them diagnose a problem.

So it’s a 77, it has upgraded 280zx turbo injectors due to a performance cam, and it has megasquirt on it. And yea between the ignition coil and fusible links it was an interesting series of events.

I swapped mine out with a blaster 2 MSD coil, youll need a smaller bracket to mount it up. It works good, i got shocked pretty hard by it one time.

31 minutes ago, heyitsrama said:

I swapped mine out with a blaster 2 MSD coil, youll need a smaller bracket to mount it up. It works good, i got shocked pretty hard by it one time.

😂 well I guess that’s one way to make sure it works. 

 

So you can test it by having it shock you to see if it's working.

And if it's blowed up, it's probably NOT working.

Mental notes. Got it.

3 hours ago, Captain Obvious said:

 

So you can test it by having it shock you to see if it's working.

And if it's blowed up, it's probably NOT working.

Mental notes. Got it.

My theory is the fusible links blew as a result of the charge thrown through the harness from the coil when it exploded.  Feasible? 

31 minutes ago, chaseincats said:

My theory is the fusible links blew as a result of the charge thrown through the harness from the coil when it exploded.  Feasible? 

Yea that’s what I’m thinking happened. I guess I’ll see once I replace the coil.

Do you have a picture of the exploded coil?  I've never seen one or heard of it happening.  An internal short could pass enough current through to heat it up rapidly but even then the negative terminal wire and positive terminal wire would have to pass the current, and the negative terminal would have to supply a ground path.  If the ignition module was shorted or the negative post wire shorted to ground, the coil could heat up more slowly and maybe get hot enough to smoke or something.

Either way, the coil itself would only be the cause of the "explosion" if it was internally shorted, and there was a path to ground on the negative post side..  More likely that the source of the failure is somewhere else.  Better check the other components before you get carried away with new parts.

Heat comes from current and current only happens when the circuit to and from the battery is complete.

19 minutes ago, Zed Head said:

Do you have a picture of the exploded coil?  I've never seen one or heard of it happening.  An internal short could pass enough current through to heat it up rapidly but even then the negative terminal wire and positive terminal wire would have to pass the current, and the negative terminal would have to supply a ground path.  If the ignition module was shorted or the negative post wire shorted to ground, the coil could heat up more slowly and maybe get hot enough to smoke or something.

Either way, the coil itself would only be the cause of the "explosion" if it was internally shorted, and there was a path to ground on the negative post side..  More likely that the source of the failure is somewhere else.  Better check the other components before you get carried away with new parts.

Heat comes from current and current only happens when the circuit to and from the battery is complete.

I attached the picture but it basically just blew the cap off and sent oil flying. The wiring is not the best so I’m going to go through it and make sure it won’t happen again, but the coil was 17 years old so I don’t know what could’ve caused it.

Was the engine running, or the key on?  I'd guess the P.O. connected the blue coil negative wire to a ground terminal or shorted it out by accident, you turned the key on, the coil overheated and popped it's top.  Is that a Blaster or did the PO just paint the stock coil red?

Download the 1980 EFI book, and the Factory Service Manual if you want to figure things out quickly.  Replace and hope doesn't do well on the EFI cars.  No offense intended.  If the PO bypassed the ballast resistor then he/she probably did something with the ignition module.  Might even have a ZX distributor on there.

14 hours ago, Reid280z said:

The po bypassed the ballast resistor

 

43 minutes ago, Zed Head said:

Was the engine running, or the key on?  I'd guess the P.O. connected the blue coil negative wire to a ground terminal or shorted it out by accident, you turned the key on, the coil overheated and popped it's top.  Is that a Blaster or did the PO just paint the stock coil red?

Download the 1980 EFI book, and the Factory Service Manual if you want to figure things out quickly.  Replace and hope doesn't do well on the EFI cars.  No offense intended.  If the PO bypassed the ballast resistor then he/she probably did something with the ignition module.  Might even have a ZX distributor on there.

 

So the car actually wasn’t running and off but I was hooking the battery back up before. And I’m not entirely sure what the po did before me, so it’s kinda hard to figure out what coil to use.