1996 ef falcon engine noise?

Hi, I was just wondering if there was anyone which could help me or send me a link on how to fix my engine noise I'am getting through my speakers I have a amp connected I have tryed buying new Rcas as I got told cause they had a little cut in the isolation it could cause engine noise but it is still there. I also ran the speaker wire again my power an ground are both run on the opposite side of the car then the Rcas. An I'am still getting very loud engine noise. All I can think of now is it could be the Head Unit but I ain't 100% sure so if anyone knows or has any ideas could you please let me know. Thank You Rizza