akz31

ok... So like the title said im getting some kind of interference. Whenever I turn on the radio with the engine on I can hear a whining noise kind of like a supercharger lol. The pitch increases with revs. I'm posting in the hopes that maybe this has happened to someone else before and they could help or if anyone knows where I should start looking for problems because I know basicaly nothing when it comes to automotive electrical...

SpeciallySpiked

Is the stereo aftermarket or original?

akz31

oh forgot to mention that it's factory. Also I guess I should have mentioned that the rear passenger speaker was replaced by previous owner and the function of the rear speakers is intermitant. Also the interferiance very rarely goes away for a day or so.

akz31

btw man... Did you buy the Porsche because it looks like the Z or the Z because it looked like ur Porsche? Lol I love older posches! Anymore pictures of it?

SpeciallySpiked

Ah I was hoping it was aftermarket and you could change were it was grounded to. In that case, I'm afraid I don't have much advice for you
I'd guess it has to do with the alternator adding more voltage to the system so if you could suppress that somehow, it'd be nice.

Very strange about the rear speaker too. Have you ever taken it out and looked at how it's connected? The wires might be spliced together and coming loose...

Well I bought the Porsche last so I guess it looks like a Z. But I've always liked the look of the Porsche, especially with the whale tail. They do have similar body styles though!

Pictures of the Porsche (when I first bought it, 2.5 years ago) and the Z:

akz31

yeah the front ends are more similar that anything else ur 911 is beautiful. What does the euro spec package entail? Any other mode?

I think it might have something to do with the speakers being grounded to the body with that common ground system or whatever. But like I said I don't know much about automotive electrical and wanted some direction before I dove into trying to fix it.

SpeciallySpiked

Thank you! The euro spec is missing some emissions stuff (especially on the exhaust) that free up some HP. Other than the gauges being in German - minus the speedo which is in MPH due to some other owner - it also has power windows and two exterior mirrors. The US models only came with the driver's mirror and manual windows. And for some reason I have a 4 speed rather than the 5 speed common in US models but that could be someone else's influence again.

I don't remember/know any other differences but I know everyone raves about the lack of emissions stuff. As for other mods, I think someone might have swapped in a different cam because it really pulls after 3.5K. It's a similar feeling to a turbo just not as strong hahaha. Someone already replaced the original cam covers with the Turbo versions that do not have warping problems which is nice.

You might want to check out a Car Audio forum - I'm sure they exist - to ask about the whining and the common ground. I know it is a common problem and there is probably a pretty good solution out there! Good luck!

WiZZard

This problem you are experiencing could be caused by a couple of reasons.

1.) The factory radios used what is called a "floating ground" on the 4 speakers. This means that the ground side of all the speakers must NOT be connected to the car's body ground in any way. This is contrary to most all other sound systems today. This can cause the problem you describe. Check all the wires for this.

2.) The more likely problem is that the spark plug wires have been replaced with non-factory, cheapo, NON-RESISTIVE wires. The factory specifies RESISTIVE plug wires to prevent the ignition pulses to each plug from being broadcasted into your 12 volt DC system. This is a very common problem. Resistive wires are usually more expensive but they don't generate the noise you are talking about.

3.) Lastly, if you are still picking up ignition noise after all this, try this. Go to Radio Shack and tell the guy there you need an Automobile Ignition Noise Supression Kit. DO NOT buy the cheap one that only contains a component called a "Capasitor" in it. Buy the better kit that has both a Transformer (also called a "Choke") and 1 or 2 Capacitors. Follow the instructions to install these components into the radio's 12 volt DC power line. This circuit will shunt the noise pikes to electrical ground before they get to your radio.

I hope this solves your problem.

Good luck,

WiZZard

akz31

Well well mr wiZZard thanks for that dude! The plug wires have been replaced with maybe a set of Accels or something like that... If u have a suggestion for wires besides OE I would apreciate it thanks again for helping!