Hello I just installed a kenwood deck in my celica along with a passive e.q. and an amp. The entire system was in my other car and worked perfectly.
-I wired it up in my celica and it works fine *except for when the motor is running I get a hissing sound coming through the speakers. The sound gets louder as you rev the motor. I know it is ignition noise from the motor but I don't know why I have it in this car and not the other car???
-What have you guys done to deal with this in the 94 celica???? Any ideas?? Thanks

WEll the damn amp wiring kit only came with one Audio cable to run to the amp for two channels when I have four so I bought a standard Audio cable apparently its not shielded and it is letting the noise into the system. So note to self only use cables made for car use!!!!! Its funny though as the same cable worked fine in the other car..... Oh well now lets rip the interior apart and run another cable yeah!!!!

Use shielded cables, as you said, but also run the power and audio cables on separate sides of the car.