Whining sound from stereo from engine

carbuff

Member
Joined
Oct 6, 2012
Messages
184
Reaction score
8
My 2001 v6 has an aftermarket jvc deck hooked up to the stock mach system with all the proper adapters and such. Its worked great for over a year. So out of the blue Im getting this loud moaning whine that varies in pitch with the engine rpm and varies in volume with the current draw on the alternator. Like if I hit the brakes it gets louder, turn on the headlights, etc. It seems to actually have nothing to do with the radio as it remains the same even if I turn down the volume to nothing. It also seems to only be coming through the mach sub speakers and not the upper tweeters. Could it be the alternator going bad? Mach amp on the way out? Sounds like some kind of bad ground situation. Also its intermittent. Sometimes its fine for a while but then kicks in the next day. Any ideas appreciated.
 
OP
OP
carbuff

carbuff

Member
Joined
Oct 6, 2012
Messages
184
Reaction score
8
Ive narrowed down that its only coming from the rear subs, not the door subs. How do the amps work? Does one power the front and one power the back?

Also everything works fine and normal when the engine is not running.
 
Last edited:

ttocs

Post Whore
Joined
Oct 9, 2009
Messages
32,394
Reaction score
5,561
Location
Evansville Indiana
I am not as up to date on 01 as I am my 94. 94 had a small can looking piece with a single wire to it on the ignition coil that was a noise reducer for the ignition that when it goes bad will cause this.
 
OP
OP
carbuff

carbuff

Member
Joined
Oct 6, 2012
Messages
184
Reaction score
8
Yes my 4 cylinder foxbody had that too. I will check it out. Thanks.

Just checked. The coil has a square black plastic thing that two wires go to. I will look into this further.
 

Werecow

Well-Known Member
Joined
Feb 3, 2020
Messages
1,043
Reaction score
785
Location
Virginia
I had one of those in my S-10 waaaaaaaaayyyy back in the day, it was a capacitor, but I can't remember the ohms it was rated for... I keep thinking it was like 20k? Does that sound right?? It's been back in the 80's when I had that set-up going on.. This one was wired on the alternator, with one lead on the hot and the other lead grounded back to the body of the alternator.. it wasn't hooked up the the ignition..
 

ttocs

Post Whore
Joined
Oct 9, 2009
Messages
32,394
Reaction score
5,561
Location
Evansville Indiana
I had one of those in my S-10 waaaaaaaaayyyy back in the day, it was a capacitor, but I can't remember the ohms it was rated for... I keep thinking it was like 20k? Does that sound right?? It's been back in the 80's when I had that set-up going on..
resistors are rated in ohms, caps are rated in farads or microfarads at this size. I am pretty sure you can still pick them up at an autoparts store.
 

Werecow

Well-Known Member
Joined
Feb 3, 2020
Messages
1,043
Reaction score
785
Location
Virginia
It's been so long ago I can't remember specifically which one it was but I keep thinking it was a cap, it had a silver body almost as big around as a nickel and maybe 1 1/2 inches long two leads very fine wire, one lead went to the hot and the other was grounded back to the alternator, I do remember getting it from radio shack, and the rating was recommended by a friend of mine who was big into building stereo's back in the day. I has an Alpine deck and amp that was making a whine just like your talking about..
 
OP
OP
carbuff

carbuff

Member
Joined
Oct 6, 2012
Messages
184
Reaction score
8
So, I disconnected the grey plug to the alternator and the noise goes away. plug it back in and you can tell the alt kicks in and rpms drop a bit and the noise is back and loud. It seems that the harder the alternator needs to work, the louder the noise. So, its not ignition noise but from the charging system, most notably the alternator. Ive found a thread online where someone has the exact same issue as me. Its like I even wrote the post,almost word for word like this one. People keep referencing two little black boxes that are rf filters but thats on a v8 and mines a v6. I cant seem to locate these boxes unless its the little black box that off of my coil.
 
OP
OP
carbuff

carbuff

Member
Joined
Oct 6, 2012
Messages
184
Reaction score
8
It's been so long ago I can't remember specifically which one it was but I keep thinking it was a cap, it had a silver body almost as big around as a nickel and maybe 1 1/2 inches long two leads very fine wire, one lead went to the hot and the other was grounded back to the alternator, I do remember getting it from radio shack, and the rating was recommended by a friend of mine who was big into building stereo's back in the day. I has an Alpine deck and amp that was making a whine just like your talking about..

Yes I had an rf choke coil from radio shack back in the day for the "killer" system in my 67 camaro. LOL. It worked though.
 
OP
OP
carbuff

carbuff

Member
Joined
Oct 6, 2012
Messages
184
Reaction score
8
So, I unplugged the amp for the rear subs and it goes away. Still have front subs and all 4 tweeters. Temporary fix at best. The problem comes and goes with the unplugging and plugging back in of the rear sub amp. Could the amp be bad? It seems to be grounded properly, its screwed into the metal with 4 bolts. Seems like a pretty solid ground.
 

ttocs

Post Whore
Joined
Oct 9, 2009
Messages
32,394
Reaction score
5,561
Location
Evansville Indiana
the amps are not grounded through the chassis. Get a little stupid and jiggle the harness going to it and see if it does anything
 

360dartgts

New Member
Joined
Apr 28, 2020
Messages
18
Reaction score
27
It's a capacitor. Not sure where it is on a mustang. Old muscle cars had a capacitor directly off of the distributor that grounded to the engine block.
 
OP
OP
carbuff

carbuff

Member
Joined
Oct 6, 2012
Messages
184
Reaction score
8
It's a capacitor. Not sure where it is on a mustang. Old muscle cars had a capacitor directly off of the distributor that grounded to the engine block.

Yup, the cap on my camaro was right on the coil bracket.
the amps are not grounded through the chassis. Get a little stupid and jiggle the harness going to it and see if it does anything

Can I just swap the amps to see if the problem follows the amp or the wiring? (are they the same) Is one of the wires in the amp plug a ground that I can just run a solid ground to?
 

Flade

Member
Joined
Dec 21, 2018
Messages
188
Reaction score
56
Location
Niceville, FL
True, hope he fixed it back then. The alternator capacitor likely wasn’t the problem. The ground wire to the amp,was. Its a know issue with Mach 460. Usually the connector behind the drivers kick panel. Needs to clean the connections and make sure it’s tight.
 
Last edited:

Monday

Member
Joined
Jul 21, 2021
Messages
213
Reaction score
86
Just curious please, did you lay any deadening down in the back - around the amps, including around the back of them where they plug in?

That was a problem with my amps about two and half years ago.

Got a big idea of having tuned exhaust without "all" the cabin noise and I sound proofed the crap out of it; messed my amps up for a couple days until I remembered, "You prolly just shorted all your shit out Smart Guy."

So, just wondering about the sound proofing...
 

Latest posts

Forum statistics

Threads
77,440
Messages
1,502,174
Members
14,920
Latest member
marktuck99

Members online

Top