What would cause static noise to start in a radio when it didn't do it before. It comes on at higher RPM range (4,000 +RPM) loud enough through the speakers that it will drown out anything that is on the radio, doesn't do it on FM or CD player. I have installed new plugs a couple months ago (less than 2'000 miles) but have same plug wires that were on the car when I bought it, Should I try replacing them or maybe add some kind of filter in the system?What works? This is my 91 Miata.... Tedd

 

You may have leaking wires, poor antenna ground, or your radio may have a filter capacitor crapping out.

 

Tedd, we had trouble with this on older cars,when I was in the used car business,and if I remember correctly,it could usually be corrected by adding a Noise Supressor that the NAPA stores carried at that time. Maybe you wil be lucky and find a NAPA store with some old geezer my age that knows what the heck I am speaking of.
Tedd ,I just found on Amazon an inline radio noise Supressor for AM/FM radios.
It's under $20 and goes on antenna wire at back of radio. Larry

 

I would look for grounds first. Antenna, chassis, case. and the hood to body for a ground as well. If it has points, check the condenser. It could be the wires, so that is a good item to replace, next. Did you use resistor plugs?


Was there any event that happened around the time you first noticed the static? Did it come on gradually, or suddenly?

 

In between snow and now monsoon I have had little time or luck trouble shooting but with a quick walk around I did find the antenna loose to the body. When or if the weather turns for the better I'll pull the car out of it's unlit mini shed and tighten up that part, could be the problem.I seldom use the radio so I don't know when it developed but with the weather as bad as it has been lately I need it for weather updates when I'm on the road. There is nothing much worse in a snow storm than a Miata with RWD and three inches of ground clearance.

Early Miata's have a pointless system and a weird firing order with 1/2 of the plugs firing at the same time but that's shouldn't be a static problem. A new set of plug wires wouldn't hurt a thing.They look brand new but so does everything under the hood.Thanks for your interest and ideas I'll up date after the storm.... Tedd

 

The half plugs firing at the same time is an old technique. My 70 Honda 750 had that type of ignition with points.


I do not live in the snow belt, but my 91 OCC with 2 1/2 inches of ground clearance would be worse. The floor jack would not go under the frame. The speed bumps are enough to ground the frame. I have since raised it to 3 1/4 inches, and I still think it would be worse than the Miata, although I can now get my jack under the frame.

 

Not a biggie but it's been a while sense I posted and the fix was as simple as putting a tight on the mast and it did take away about 70% of the problem, good enough for AM anyway... Tedd