Audio Systems: Radio Problem, radio problem, engine computer

Question
Tom,

I'm pretty experienced in car audio myself yet I have a problem that is puzzling me.  Ever since I can remember (5 years), I have had a problem with my FM/AM radio.  For some reason, it seems as if there has always been interference and I could only tune in the very strongest signals.  Only recently did I discover that the problem is not there when the engine is off as the radio is perfectly clear!

I have been through a few aftermarket CD players and the problem has always been there.

Do you have any ideas what could be causing this?  Someone brought up an idea regarding the type of spark plugs.  Is this possible?


Thanks


Answer
Jason,
Noise can be generated by the engine computer, fuel pump and other DC motors including the alternator. The noise that you hear will tell you if the spark plugs/distributor or the alternator is the cause. When the engine is running and you hear a whine that goes up and down with engine speed the alternator is causing the whine. And if the noise is a pop-pop type of noise, faulty plug wires, spark plugs and worn out rotor and cap can cause that noise. If the engine is fuel injected the filters on the injection solenoids can fail and they will make a loud snap/click in the speakers. You can sometimes knock down the noise quite a bit by installing resistor plugs and wires and replacing the cap and rotor.

TOM,
T&D ELECTRONICS
tdeser@zoominternet.net