Audio Systems: Horrible Feedback From engine, series capacitor, active crossover

Question
System Setup- Pioneer DEh9800 receiver,1.5 Farad RF Power Series Capacitor, 4 RF Power Series Component speakers, 2 12' L7 solo kickers, Kicker ks850 4-channel for speakers, and a Pheonix Gold amp (1200 watts) for the subs.
I heard a rattle coming from my backdoor, so I took off the door panel and left the wires attached from the crossover to the tweeter (which was stationed in the door still)and placed the panel on my seat. I went to turn on the music to hear the point of rattle and the bass hit made the panel fall on the ground and ripped out the wire from the tweeter to the crossover. WHen this happened the bass started to thump sporadically and VERY loud. I put the wires back into the crossover,turned on the car, and then noticed that both tweeters on the right side of my car werent working, and the louder the volume on my amplifier was set, the higher the feedback was from the engine through the speakers. I've never heard such loud feedback from an engine and don't know if I blew the amp or messed up a groundwire. It's that type of high pitched sqweal sound that gets louder as you step on the accelerator. I can also hear my cds loading through my speakers now. And the woofers carry a little bit of the music through them now too (but this I can fix on my own). Any suggestions or input would be greatly appreciated cause I am clueless about what happened. Thank you.


Answer
What you listed would be called system components. It is far from a basic system setup explanation (which would be neede for a consise answer).
So generally:
The subs thumping is likely a bad ground, so start there.

I am not sure which PG amp you have or how it is crossed over but (presuming you are using an active crossover near the amp [or in it]) there is nothing that happened that would have made the subs start reproducing higher freqs than they did b4 this happened. The mids and highs are on a different amp, so this may indicate that the deck (or at least something north of the amps) is at fault.

If you want to re-submit this question privately, I will be happy to walk you through how to localise and isolate the noise problem. Though entertaining to read, how it occured is a moot point, imho.


Sincerely,
Jerry Mael