HELP - Whistling Noise Coming Through Speaker

I'd sincerely appreciate any guidance as my local Maserati dealership has been unable to resolve this frustrating issue in my 2 visits to them with my 02 Maserati Spyder GT.

For the past couple of years (every few months before and now EVERYDAY since my last visit to Maserati dealer), I get a whistling noise that sounds through my speakers. It happens when I hit a bump. I can be cruising along without any disturbance and when I hit a bump, a whistling noise sounds through speakers and increases pitch and volume with acceleration. To me, it sounds like a short somewhere caused by something moving and contacting metal when shaken.

So, while under warranty, I took to Maserati along with other warranty work. They said they fixed it and it was due to the passenger door speaker being installed upside down. Weird since the speakers are stock and to my knowledge, never been touched. Despite being charged a couple hundred bucks by Maserati, I was pleased that sound was gone.

Then several months passed and I hit a bump and back came the noise. I took it back to the dealer with the car now out of warranty. I noted that it's the same noise and spoke to same guy who listened to the noise with me and remembered it from year prior. They kept it a week and again said they fixed it (and again charged me a couple hundred bucks) but this time said they again focused on the passenger door speaker and did something to further insulate it. He assured me that the problem was resolved. As I pulled out of dealer parking lot, I heard the whistle again. I pulled back in and brought him out to the car so he could hear it. He said for me to leave the car with him when I can again be without it for a while. I haven't brought it back yet.

I don't think they have a clue what's wrong. I personally think it has nothing to do with the stereo system per say but instead the speaker is just the means of transmitting the sound from the short that's occuring somewhere in the car. Anyone have any thoughts? And do you think I should take it back to Maserati or seek out an electrical guy (e.g. a car stereo / entertainment system shop)?

Here'a a few additional observations that may help someone identify the cause & a possible solution:

1) Noise starts with stereo on or off
2) If noise starts with stereo on, the noise through speaker does not disappear when stereo turned off
3) Before 2nd visit where they did some insulation work to passenger speaker, the noise came out evenly from both speakers and music played out of both speakers. Now since that work was done, driver's speaker loses all audio when noise begins and the whistling & music only transmits out of passenger speaker.
4) I found that sometimes I can eliminate whistling sound and regain audio out of both speakers by briefly increasing stereo volume to full strength then turning down... well until the next bump when the whistling comes back
5) I can often get whistling noise to end by turning off car at traffic light and re-starting
6) I've tried putting in a bigger fuse but that did not help
7) I can take out stereo fuse and I eliminate noise (but am musicless....)
8) I've looke dunder the dash and I don't see any obvious wire contact issues

I'm keeping my fingers crossed that someone may have a thought on the problem and a potential solution. Many thanks!!

 

Some folks have mentioned the following as the potential issue. Do either of these sound right?

"If your problem is harmonic noise that is coupled to the RPMs of the car it can be due to noise coupling on the power line to the receiver or amplifier, problems with the radio antenna, internal problems with the receiver or amplifier but not due to wiring to the speakers."

"The noise you are hearing is due to EMF coupling into you audio amplifier.
You can diagnose whether it is picking up the noise from the RF (radio) circuit or the power circuit by disconnecting your radio antenna from the back of your receiver. If the noise goes away when you disconnect the antenna, you have some type of issue with the shielding on the antenna or other circuit problem in the receiver. If the noise is still there, it is likely noise that is being fed along the power line into the back of the receiver and coupling in (as was the case in my car)."

 

Thanks for the note Willy. Yes, it is with RPMs, higher RPMs=higher pitch and lower=lower. So I will start by knocking the stereo unit while the car is not in motion to see if that causes anything. I'll then take a look at the battery. After that, I guess I will take it to a shop since I am not familiar with wiring. I'll just have to decide if I go back to the dealer and see if they can figure it at no added expense to me (since I have already been 2 times), or I might just bite the bullet and go to a car stereo / entertainment shop as I am sure they are good at finding this stuff.

Anyway, I will let you know what I find out. I learned on a Maserati site through a similar post that another guy has the same problem which he too can't seem to resolve. Hopefully, the tips I've received here will solve this mystery!

Thanks again!

 

Thanks again to all of you whom have helped. I just wanted to update you that I took my car back to the local Maserati dealer with a detailed 3 page letter of tips you provided and others received from colleagues. I decided to give the dealer another try since it is a rare car and more so because I am stubborn! I told them that I first brought my car to the with this noise under warranty then again after and both times they did not fix it. I told him not to return it to me until it is resolved and told him that I expect it to be free of charge since they failed to fix it propoerly while under warranty. He apologized and said they would resolve it but these things can be difficult and Maserati doesn't do much to help them diagnose these types of issues which is a frustration to him.

Well, it's been a full 2 weeks and I haven't hard from them yet. I plan to call tomorrow and am keeping my fingers crossed. Wish me luck!

I will let you know how things shake out.....

Thanks again!