I just hooked up an adapter, splice into the speaker wire and so i can run my subs with factory deck. After i did this i turned my car on, speakers worked fine, so i turned my car off, the speakers hit a really low bass for about 2 seconds and then shut off, wondering what this could be?

Maybe its feedback from the factory deck. Its could have always been there but now the subs amplify it...

my lumina used to do that with my aftermarket deck, so its prolly not because of the stock deck.

It could be the deck amps cycling off. My 80'* home reciever does that.

That may be a "pop/fart", I think. I don't remember what causes these but its not anything to worry about.

hahaha "pop/fart" somethg to do with the capacitors discharging

Yep, the speakers pop and the subs fart.

I would recheck your ground. After awhile this could damage your subs. Mine would do that when I would turn the car off/turn the radio off. Changed the ground to a different spot and it went away.

are you running a older amplifier. some older amps did not have a quiet turn on/off feature and they would make noise when you shut them off. basically what you are hearing is the radio signal shutting off before the amp does. most new amps have a feature to keep this from happening but that would be my guess!

Could it be the RCA adapter, the thingy that i spliced into the speaker wires with, would i have to ground that, it has ground wires for that, maybe thats it, any other input?