NX Nitrous and gas solenoids both have cracked coils. I may have overtightened the nut on these as they came for NS very loose. If the coils are cracked are they shot even if they cycle when 12 volts applied??? Do the coils need replaced?
If they do need to be replaced, I would change solenoids. The last NX coil that I bought cost almost as much as the solenoids that Steve sells. On top of that, I had to wait about 3 weeks to get it. I won't do it again.
If you are looking at the coil and the inside appears cracked look at it close. Sometimes the casting will appear to look like a crack and it actually is not.
If they are cracked and not showing signs of over heating it was due to being over tightened. If you have one of there new style solenoids with there fake carbon fiber cans they usually break before you will hurt the coil.
If your coil is cracked you can get a replacement coil.