1998 honda civic lx wire/wires popping off

[honda_civic_lx]

hey guys..what could be causing the 2 nd spark plug wire to come off..?? could it be the fuel injectors or the pcv valve ?? i have had someone tell me its the pcv valve clogged up and building pressure to pop off the wire..does anyone know what could be causeing this to happen and almost not connect to the plug..i hope someone knows what is causeing this..if anyone knows whats happening or has had it happen to them tell me what it could be...thanks alot guys