Annoying engine noise bleeding into audio

[mhespenh]

Annoying engine noise bleeding into audio -- Solved!

Hey folks!

First I want to say thanks to :SNSign: for all the awesome help and advice I've gotten lurking through the forums.

So I've got a 94 GT 'Vert 5-spd with the Mach 460 audio and an aftermarket head unit. Mostly stock, aside from Magnaflow catback ('packs) and CAI. I did some searching around, but couldn't find anything that matched my problem, so perhaps someone can help me out:

Seemingly randomly I will get a VERY annoying whine with a pitch that matches the RPMs (although the volume is independent, sometimes loud, sometimes soft, independent of engine RPM and radio/CD volume) bleeding into the audio. It comes and goes as it likes, sometimes it starts when the car starts, sometimes it starts 20 minutes later. I know it is coming from the amp: You know when you start the car there is that delay while the amp powers up? The whine doesn't start until after that. Also, I should point out that sometimes turning the stereo off (which turns the amp off also) and back on makes the whine stop, one out of three times that trick works... for a little while.

Any ideas what could be causing it, and ways I can go about fixing it would be most appreciated. I bought my 'stang when I got back from overseas (Marines) but never had the time or money until now to start building it out, and I can't take this 'ng noise anymore. Gotta tackle the little things first.

Thanks guys,
-Michael

Solution:

I had the exact same problem a couple of years ago with mine. I also have Mach 460 on my 94 Coupe. I tried using different plug wires and even changed the capactior on the coil as mentioned above. I finally figured out by accident that the wire harness for the stereo that is under the carpet on the driver's side (just aft of the kick panel) was not connecting very well and was causing the noise. I figured it out because when I would jossle or wiggle the harness it would come and go. All I had to do was wrap a crap-load of electrical tape over the harness (from one harness to the other, keeping a tight connection) and so far I have been noise free for a couple of years now!

Good luck!

 

[Chythar]

You're getting electrical interference from the engine electrical system. I had a similar situation on my V6. In my case, it went away when I changed the spark plug wires to a different brand. When was the last time you did a tune up?

 

[HISSIN50]

Good stuff above.

I don't have a Mach stereo system but the common issue I've seen guys post about is a bad ground wire in the passenger kick panel.

Do you still have the radio interference capacitor? It's mounted on the ignition coil bracket.

 

[mustanggt94]

I had the exact same problem a couple of years ago with mine. I also have Mach 460 on my 94 Coupe. I tried using different plug wires and even changed the capactior on the coil as mentioned above. I finally figured out by accident that the wire harness for the stereo that is under the carpet on the driver's side (just aft of the kick panel) was not connecting very well and was causing the noise. I figured it out because when I would jossle or wiggle the harness it would come and go. All I had to do was wrap a crap-load of electrical tape over the harness (from one harness to the other, keeping a tight connection) and so far I have been noise free for a couple of years now!

Good luck!

 

[mhespenh]

Thanks for the suggestions guys, I'm tearing the interior apart today/tomorrow to install a push button start and keyless entry (stock keyless if FUBAR), so I'll check out the harness, interference cap, and if it comes down to it replace the plug wires.

I'll let you know what I find.

Thanks!

 

[It's a 5_0 HO]

Not trying to jack the thread or anything but i have the same problem. When i leave the car running and i open the door (driverside) shut it and then open it again. I get interference. I lose all bass from the mach 460 and i have to shut the car off turn it back on and it goes away till i open the door and leave it running again. Sometimes it does it just driving around but not as much.

 

[mhespenh]

Not trying to jack the thread or anything but i have the same problem. When i leave the car running and i open the door (driverside) shut it and then open it again. I get interference. I lose all bass from the mach 460 and i have to shut the car off turn it back on and it goes away till i open the door and leave it running again. Sometimes it does it just driving around but not as much.

This is just an idea off the top of my head, but you might want to check the connections to the rear speakers. Most of the bass comes from those speakers, and they are right next to the door- so maybe shutting the door is jostling the connections?

Just an idea.

 

[Chythar]

This is just an idea off the top of my head, but you might want to check the connections to the rear speakers. Most of the bass comes from those speakers, and they are right next to the door- so maybe shutting the door is jostling the connections?

Just an idea.

This is a good one. There's a connector for the Mach460 wiring behind the driver's kick panel next to the door. If something's loose in there, you'll have trouble every time you shut the door.

 

[mhespenh]

I had the exact same problem a couple of years ago with mine. I also have Mach 460 on my 94 Coupe. I tried using different plug wires and even changed the capactior on the coil as mentioned above. I finally figured out by accident that the wire harness for the stereo that is under the carpet on the driver's side (just aft of the kick panel) was not connecting very well and was causing the noise. I figured it out because when I would jossle or wiggle the harness it would come and go. All I had to do was wrap a crap-load of electrical tape over the harness (from one harness to the other, keeping a tight connection) and so far I have been noise free for a couple of years now!

Good luck!

This!

I tore out the carpet, found the harness and voila, no more whine. I'll post a pick of the harness in question when I get a chance.

Thank you!

This is the harness (the black one), just wrap it really tight with electrical tape, mine was reallllly loose

Look in this general area under the carpet to find it (draw a line straight down from the hood latch and you'll find it):

(excuse the dirty carpet, I've been doing work on the interior and haven't cleaned up yet...) :Zip2: