What can I look for for a cause of engine noise in my speakers?

I have a 1992 Town & Country with the Infinity Sound System. The engine noise in the speakers is mostly low in frequency, and is not affected by the radio, with the exception of the volume and power (I tried fiddling with the equalizer to see if the engine noise would change at all, but it the sound of it went unchanged). When the van is idling, it makes a bit more speaker rumble than when driving.

I did lose two engine ground straps (they rotted). I replaced one so far. Could this be a possibility for the cause of it, or do the ground straps serve another purpose? I do not recall if the radio made the noise before losing the other strap, as the van was out of commission for a year or so.

 

Grounding problems are usually at fault when this happens unless there is a short somewhere in the radio. This is factory radio correct? While idling, does the sound get faster when you rev the engine? meaning as the alternator spins faster, the whine goes faster? Have you ever had the radio out? Have you been messing with connectors behind the dash or climate control system?

 

Yes, it is a factory radio. It's the third one I've had. The first ate my mp3 player tape adapter, the second never worked right, and then I got this, so it has been out of the vehicle before.

The sound is mostly present while idling or when the engine is in low gear/low rpms. When driving, as long as I am accelerating, or the engine is above 1000 RPM or so, the sound does go away, and does raise in pitch before doing so. I'm not certain, but it may be worse when it's humid/moist?

I will get another ground strip to replace the other missing one (which originally connected somewhere near the alternator) to see if that helps. I'm also going to pop the radio out and re-seat the connectors. I'll let you know if these fix it.

 

Sounds like good plans. Its funny you say ground strap on alternator as in the Dodge ram trucks (maybe others) the was some sort of issue like about a strap needing to be added because I was making the truck shift into different gears.

Read this..
I hope you have your fix by now, but I will send you my experience and fix anyway. Maybe it will help if you are still experiencing the problems. I had the same problem related to electrical noise from the alternator to the APPS,
causing the torgue converter to lock and unlock at about 30MPH with overdrive off and at 50 MPH in overdrive.

 

I haven't gotten the second strap yet, but now I'm wondering if that is even the issue. It's gotten worse the past couple of days.

I thought the volume **** on the radio could affect the noise, but it does not. If the radio is on, there is electrical noise, at a fixed volume and frequency level (meaning the equalizer does not affect it). Apparently even when the engine is not running... (it makes a deep thud if I put my eletric windows up or down with the van off and radio on).

I'm pulling the radio and trying one of my old radios that still partially work to see if that's an issue.

 

Well, good news and bad.

I have three spare radios. I popped the original in (which I replaced a couple of years ago... broken tape deck) and the noise was nearly gone except for a very light sound in the very low fequency range.

I tried the replacement I originally bought (need tape deck for my mp3 player adapter) and there was no noise whatsoever. However, the tape deck is also bad on this one.

Oddly enough, I have a third, non-Infinity spare that I got out of a junked Caravan about a month ago, and hooked that up, and no noise either. From all that I've read about the Infinity Sound System, they say you can't use a non-Infinity head unit and still get sound from the speakers, yet this one works. Sadly, it ALSO has a bad tape deck. Sigh.

So it would appear that the grounding in the radio itself may be the issue. Now I need to find one that works right so I can still listen to my music. (Used to have an FM transmitter for it, but the tape adapter sounds much better).

EDIT: The radios have two supplier codes. The ones with supplier 07910 have no hum or noise in them. The original and most recently used radios that do have hum are supplier 28406.

 

Interesting.. those tape deck adapters have alwasy sounded the best to me. even over direct connection in some vehicles.