I just finshed restoring a '74 Super Beetle Cabrio and just installed a Radio w/CD Changer. The radio somehow picks up the ignition noise in the background, that sounds static and cracking type, when the engine is running. As soon as the ignition is turned off, the radio becomes clear again. Changed to Petronixs carbon core plug wires, checked antenna cable ground, installed a 470uF capacitor between Ground and coil + terminal. These did not help. Could someone shed some lights as to what else I could do to get rid of these ignition noises? Regards, Jeremynb
Did you hook up an amp too? I am no expert, but how did you wire power to the radio? Was it off the ign switch? Maybe a different wire from the fuse box (constant power) might make a difference. Also is that the original ign. coil or an aftermarket coil? Where is the noise coming from? Rear speakers only? Does it happen faintly with the radio off also? Did you use those Monster speaker wires? just some thoughts. later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris
This is actually a pretty common problem, I think it's most normally called "alternator whine" or something like that.
A pages on the subject:
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There are scads of ways to fix the problem, from what I understand plugging a filter into the wire works just fine, but is not considered the "optimal" fix.
Hi Dave, Thanks for your response. The coil is a Bosch, made in Brazil, new one, although not the 'original' one that came with the car. I do not have any amp nor rear speakers. The CD plays fine and is totally noise free. When the radio is off, there is no noise. Regards, Jeremy
Then I would check the antenna, esp. for improper grounding at it's base. Again this is just an uneducated guess! :-) let us know what you find. later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris
Not a chance. Your noise is being carried into the electronics either through the +12VDC in, or being cause by a poor ground from the radio, or poorly-shielded antenna feed. Double check the antenna feed for good shielding (visual inspection), and make sure that the radio is earthed to the chassis really, really well.
Thanks for your advices. I tried running a separate wire from the radio chassis to the body Ground. That did not do it. I tried running the antenna shield via a separate wire to the Ground. That did not help either. If the noise is carried into the electronics via the +12VDC, what can you do to get rid of it? Also, Could a faulty coil be giving rise to these noises? Please advise. Regards, Jeremy
Squirrels advice is good,................I'll add just one more thing to the list of possibilities.
If you have a Resistor coil, and Non-resistor plugs in the ignition circuit,.....................this will cause what you are talking about also.
Just a thought................I recommend both pieces matching, and make them resistor type.
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It's is not, it isn't ain't, and it's it's, not its, if you mean it is. If you don't, it's its. Then too, it's hers. It isn't her's. It isn't our's either. It's ours, and likewise yours and theirs. -- Oxford University Press, Edpress News
Could you please enlighten me as to what is a Resistor Coil & Resister Plugs? Where could I buy them from and how do you identify them? Please advise. Regards, Jeremy
You monkeys are getting all the various terminology mixed up.
Coils come in 2 main flavors, internal or external resistor. Neither of which have anything to do with noise suppression. An internal resistor coil means it can take a full 12 volts (battery voltage) while an external resistor coil needs just that.....an external resistor to reduce the battery voltage down to about 8 volts. If you attempt to use an external resistor coil without a resistor you will overheat the coil resulting is early failure and the very real potential of it exploding (from built up pressure because of the overheated oil)
Spark plugs are available with an internal resistor that suppresses radio noise. Ignition wires are made as either solid core (very noisy) or radio suppressed.
Boils down to this, plugs, wires, alternator (generator) are the main culprits of radio interference. Yes, some emanates from the dist cap, but there's not much you can do about that......only Corvettes and Avantis came with shielded distributors and ignition wires, but these are fiberglass cars and presented large shielding problems.
It is my experience that most of the die hard folks that are trying to keep costs down will save a nickle on every eight spark plugs by buying the "cheap ones" because they don;t know they are Non-Resistor type. Probably what most of us here run, not even knowing what we have done..................A major source of noise in later model cars for sure if the wrong plugs are installed. That's the gist of it anyway.
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It's is not, it isn't ain't, and it's it's, not its, if you mean it is. If you don't, it's its. Then too, it's hers. It isn't her's. It isn't our's either. It's ours, and likewise yours and theirs. -- Oxford University Press, Edpress News
There are several different sources of engine noise. The ignition is just one. The generator and alternator are the other. Spark noise sounds like little ticks, while charging system noise is more of a whine, but both speed up as you rev the engine faster.
To fix ignition noise, make sure you have the correct spark plug wires that include the brown plastic Bosch SP connectors on the ends. These contain 1k resistors which damp out RF noise. There should also be a Bosch suppressed (resistor type) rotor in the distributor. This has 5k Ohms of resistance in it. Make sure that all the parts are good and that there are no breaks in the cable conductors.
Fixing charging system noise can be harder. You can add a capacitor to ground from the D+ terminal on the generator, the D+ terminal of the voltage regulator, and the B+ terminal of the voltage regulator. An extra capacitor at the fuse box won't hurt either.
For both sources you need to make sure that the shield of the antenna cable is grounded to the fender AT THE FENDER. To check this, unplug the antenna wire from the radio and check the resistance from the outside conductor to the chassis of the car. It should be less than a couple of ohms. These are often corroded away at the fender and you may need to replace the antenna.
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----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA
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