Audio Systems: car audio fault finding, rockford fosgate subs, inch speakers

Question
hi,
   i have just installed a pioneer p7750 head unit with fokal front splits 6inch with tweeter, rockford power series 6.5 inch speakers in the rear doors, orion 4 channel amp, orion mono block amp and two 10 inch rockford fosgate subs. all speakers are running of the 4 channel subs off the mono block. problem. the rear left hand side speaker cuts in and out. i have checked the connection at the 4 channel and it is all fine. the earthing system i did in the boot is a little dodgy i think it might have something to do with it im not sure. i havent checked connections at the actual speaker yet which is what i plan to do next. is there any other suggestions u can give me as to why it is cutting in and out.

Answer
sounds like it should be a great setup. you may have a short or a break in the speaker wire somewhere going to the door speaker.  I would run a temporary wire directly from that door speaekr to your amp.  dont worry about routing it through the car just lay it on the seats and stuff to get it wehre it needs to go.  Then drive around for a few days on this temp wire,  if the problem goes away then you found it,  just route your new wire so it's hidden.  If the problem persists let me know but I doubt it will.