Ok... Sounds like it's starved of power. What size wire is running to the sub amp and have you checked all of your connections, especially ground?

 

Check you ground.
It could also be a shorting sub.

 

i'm using 8 gauge power wire, i checked all the connections a 100 times and the ground a thousand times

 

8 gauge on 500watts rms ur wanting for a fire i think upgrade that thing to 4gauge or bigger

 

^^^^^ lol, I was thinking the same thing... I use 8ga for sub speaker wire.

 

Bingo ladies and gents! 8AWG is too small for 500WRMS. Upgrade to 4AWG and do the "Big Three" with some spare wire. Even upgrading with your old 8AWG that you're pulling out will be better than factory. 4AWG is best, but if you're strapped for cash, the 8AWG is better than stock

 

but the thing is the system worked for abour 2 weeks till i changed up my settings and now i got this problem, so i was think that its something in the amp

 

It could be a bad connection somewhere on the circuit board. If thats the problem it would just be a matter of re-soldering it.

 

does that mean i've got to take my amp appart

 

The only thing that came to mind for me outside of wiring is a smoked capacitor or a cracked/blown transistor. A smoked capacitor usually shuts the whole amp down, but I could see how it would act as though it was starved for power. JL uses transistors to transfer heat from the board to the case for heat dissapation, so theoretically, if one was blown the amp wouldn't be able to transfer it's heat causing the amp to shut down under a higher load. In both cases though, most amps will shut down and stay that way as a safe gaurd to avoid fires/excessive damage. Either way, I would upgrade the 8AWG to 4AWG and do the "big three" with at least the 8AWG you pull out... No matter what is wrong with the amp. I think you got lucky with the amp up to this point.