Help shooting really odd engine noise...

rscecil007 · Post by **rscecil007** » Mon May 03, 2010 5:39 pm

So I've got a noise that suddenly come through my system and I can't figure out what is causing it. I'm familiar with troubleshooting engine noise and whatnot, I've tracked down an alternator whine in the past. Here's the deal.

First noticed it about 2 days ago, and I've had my system installed since January. Just a higher pitched noise coming through the front components, moreso the tweeters though. It does it very very minimally when the car ignition is in the acc or radio only position, as in you have to put your ear right next to the tweeter to hear it. This may just in fact be the noise floor of the system, but it's negligible either way. When you turn the ignition to the position like you are going to crank the car (but you don't), it gets louder and easily noticeable. If I do crank the car it does not go up and down in pitch with the revs of the engine like it was the alternator. The noise also doesn't get louder when I turn up the volume, whether the car is running or not. It's just a consistent level buzz.

Here's the odd thing - I can push on one corner of the dash kit trim or another, or wiggle the main part of the kit the radio is in, and it goes away, OR comes back/gets louder again. I can also take the trim off the kit, where I can reach in and move the wires around with my fingers, and the same thing happens. Wiggle it a bit one way, goes away or gets quiet, wiggles a bit more, comes back. I did take the deck out and check, all connections from the deck (Pioneer PRS 800) and to the RCA's, power, remote, blah blah are all solid.

My initial thinking is that maybe some wires in the back are touching the case of deck and some metal back there maybe? The cross brace in the dash of the truck is like a metal roll cage bar, and is right behind the radio.

Any other suggestions or thoughts would be REALLY appreciated. Granted I haven't had tons of time to spend on it yet b/c of work, but any idea to initially chase down would help. Thanks!

waynehead · Post by **waynehead** » Mon May 03, 2010 6:02 pm

I wish I knew because I occasionally have the same thing going on. I just assumed it was some kind of interference because it wasnt until I turned up my tld that I began to notice it. The benefits of the tld totally made it worth it. Plus I cant hear shit for noise when Im jamming

rscecil007 · Post by **rscecil007** » Mon May 03, 2010 6:19 pm

yeah, i can't hear it normally either going down the road, but if a cd changes tracks when i'm at a stoplight, I can hear it easily.

Drives me nuts. I have to figure out what it is.

Post by **smgreen20** » Tue May 04, 2010 4:42 am

My first 2 thoughts were 1) HU issues and 2) Is it a Pioneer HU?

Both are yes. I can't speak about the PRS800, but Pioneer has issues with noise in their HU's. I'm not sure but the 800 might have a pico fuse inside and when that blows you get a whine. I have yet to here this whine first hand so I couldn't say if it's engine whine or just a plain whine as is your case.

My other suggestion, if you have the parts, is to replace each component 1 at a time until the whine disappears.

I would start w/the HU as you know it causes your issues now, and it also could be that your HU has developed a short internally.

rscecil007 · Post by **rscecil007** » Tue May 04, 2010 4:50 am

I def don't think it's the Pico fuse issues some Pioneer's have. That's a pretty much constant buzz no matter what you do or if the engine is on or not, etc. Plus, I haven't ever hot swapped the RCA's on the HU, and made sure they were the last thing I connected.

Unfortunately, I have no extra parts to swap out components.

Could it be a possible internal short, if just wiggling the wires can make the noise come and go (being that the headunit remains perfectly still?)

Post by **stipud** » Tue May 04, 2010 6:27 am

Do you have an RCA to headphone wire somewhere? You can use your music player to test the amp. Hell, you can even hook up your DVD player or something similar with an extension cord

Check out the tech tips attachment here:
http://phoenixphorum.com/trouble-shooti ... vt178.html

rscecil007 · Post by **rscecil007** » Tue May 04, 2010 9:34 am

stipud wrote:Do you have an RCA to headphone wire somewhere? You can use your music player to test the amp. Hell, you can even hook up your DVD player or something similar with an extension cord

Check out the tech tips attachment here:
http://phoenixphorum.com/trouble-shooti ... vt178.html

Yup, sure do! I will def check that this weekend if I don't figure it out first. (Have to take the passenger seat out to get to the amp connections.)

dwnrodeo · Post by **dwnrodeo** » Tue May 04, 2010 10:56 am

I am having a similar issue with my Pioneer PRS880 headunit. Except it only happens when my headlights are on. Possible differences in where they are grounded at.

rscecil007 · Post by **rscecil007** » Tue May 04, 2010 11:31 am

dwnrodeo wrote:I am having a similar issue with my Pioneer PRS880 headunit. Except it only happens when my headlights are on. Possible differences in where they are grounded at.

I might try grounding mine to another spot. Right now it's just grounded into the headunit/factory wiring harness.

But FWIW, I only have one amp, and I ran the ground wire all the way back to the battery, and also have the big 3 done, with neg batt to chassis (fender), and neg batt to alternator case bracket.

Post by **ttocs** » Tue May 04, 2010 12:16 pm

I would try grounding the outer shield of the rca's, it is the first thing I do on a pioneer deck with noise and it only takes a couple of seconds to test out.

justplainjerry · Post by **justplainjerry** » Tue May 04, 2010 6:08 pm

I drop my two cents in, might be all its worth haha. Definitely check all grounds and make sure there clean and tight. might be a ground loop, if all components are chassis grounded. Best suggestion... add a capacitor to the positive side of the ignition coil, then to the power feed wire to radio, amp or both. capacitor must be grounded, use automotive condenser, if not I suggest a 470µf, 50 volt electrolytic capacitor, prolly find at radio shack. AND...OR... install a radio choke, hook up same as capacitor.

radio...add capacitor˜ground....add radio choke....fuse...ignition..

hope this works for you

oldschoolfan · Post by **oldschoolfan** » Tue May 04, 2010 6:54 pm

I would rule out the ignition noise option. You stated that it happens with the key in the accessory position. There should be NO power to the ignition system with the key in this position. Let me clarify, I know we all call the "key" receiver on the steering column the ignition. I am speaking of the actual, let's light the fuel in the engine, ignition. This system is not powered with the key in the accessory position therefore it cannot cause your noise issue. Also if it were the ignition coil or coils, the sound would change with engine rpm. Yes, you did briefly elude to that not happening.

rscecil007 · Post by **rscecil007** » Tue May 04, 2010 7:42 pm

oldschoolfan wrote:I would rule out the ignition noise option. You stated that it happens with the key in the accessory position. There should be NO power to the ignition system with the key in this position. Let me clarify, I know we all call the "key" receiver on the steering column the ignition. I am speaking of the actual, let's light the fuel in the engine, ignition. This system is not powered with the key in the accessory position therefore it cannot cause your noise issue. Also if it were the ignition coil or coils, the sound would change with engine rpm. Yes, you did briefly elude to that not happening.

Yes, that's the deal. Happens very faintly in the "ACC" position, but just gets more audible when I throw it in the "start" position (what you call let's ignite the fuel position.)

BTW, I may have forgot to mention, when I pulled the deck all the way out of the dash when I was messing with this briefly the other night, no noise at all, at least with the key in the "start" position. I moved the headunit around, moved all the wires around, nothing. Slapped it all back together, bam, noise came right back. Wiggle the trim piece, noise is gone.

ttocs,

I know about the RCA trick. Might be a PITA for my HU since the RCA's aren't on the back of the deck, they're on a pigtail. I'll try to borrow my friends DMM and check for continuity b/w the HU chassis and the RCA's.

Post by **ttocs** » Tue May 04, 2010 8:56 pm

Pioneer rca's have known to have this issue for some time. Humor me and just ground the outer shield of the rca and see what happens.

dwnrodeo · Post by **dwnrodeo** » Wed May 05, 2010 3:33 am

rscecil007 wrote:
dwnrodeo wrote:I am having a similar issue with my Pioneer PRS880 headunit. Except it only happens when my headlights are on. Possible differences in where they are grounded at.
I might try grounding mine to another spot. Right now it's just grounded into the headunit/factory wiring harness.

But FWIW, I only have one amp, and I ran the ground wire all the way back to the battery, and also have the big 3 done, with neg batt to chassis (fender), and neg batt to alternator case bracket.

Same here. I have a Roadster 66, with 1/0 gauge for the big three, and dedicated 1/0 positive and negative directly from battery to amp. When I get a chance, I will try grounding the outer RCA's and if that doesn't work, I will ground my H/U directly to the battery to see if that helps.

Post by **ttocs** » Wed May 05, 2010 3:39 am

this was an issue almost 10 yrs ago and they still have not fixed it. Ask me why I have never owned a pioneer?

Just pull the rca's apart, and when you slide them back togther just stick a piece of wire between the outer shields and then you can just ground that wire.

rscecil007 · Post by **rscecil007** » Wed May 05, 2010 4:41 am

ttocs wrote:this was an issue almost 10 yrs ago and they still have not fixed it. Ask me why I have never owned a pioneer?

Just pull the rca's apart, and when you slide them back togther just stick a piece of wire between the outer shields and then you can just ground that wire.

Yeah, there's a 10 page thread over on diyma about this and the damn pioneer pico fuse issue. Seems like if your pico fuse is blown though, the noise is really bad and constant, kinda the opposite of my situation. But I will try it ttocs. Anythings worth a shot.

BTW, when the noise showed back up this morning, I muted the tweeters off the headunit, and the noise persisted. Not sure what that says about the issue.

davewaibel · Post by **davewaibel** » Wed May 05, 2010 10:49 am

I would suggest looking at your crossovers, if your running components- they are very large noise magnets- those coils are likely entry points for noise, if there are any harness' near them, move the harness and see if the noise goes away- just a thought- I had an engine noise problem, and it ended up being one of my passive crossovers-

Post by **ttocs** » Wed May 05, 2010 12:07 pm

really

? Never heard of something picking noise up after amplification that can cause issues.

Post by **smgreen20** » Thu May 06, 2010 4:37 am

Yes xover will pick up noise, but it would be of the engine whine type that fluxuates with the engine RPMs.

Therefor, I would rule out the xover. Worth a check though none the less.

rscecil007 · Post by **rscecil007** » Thu May 06, 2010 4:43 am

davewaibel wrote:I would suggest looking at your crossovers, if your running components- they are very large noise magnets- those coils are likely entry points for noise, if there are any harness' near them, move the harness and see if the noise goes away- just a thought- I had an engine noise problem, and it ended up being one of my passive crossovers-

No crossovers guys, running my comps active off the headunit.

I'm still leaning towards something in the cabling is getting tugged or pushed loose when I get the headunit installed, or the wires are getting pinched causing a connector to get tweaked at an awkward angle causing a bad connection, something like that. Plan on figuring it out this weekend, still no time as of yet.

Dave, check your pm's.

Post by **stipud** » Thu May 06, 2010 6:03 am

Where is your fuel pump located? Any wires near it?

rscecil007 · Post by **rscecil007** » Thu May 06, 2010 7:16 am

stipud wrote:Where is your fuel pump located? Any wires near it?

The fuel pump's in the gas tank Tom.

Post by **stipud** » Thu May 06, 2010 8:32 am

rscecil007 wrote:
stipud wrote:Where is your fuel pump located? Any wires near it?
The fuel pump's in the gas tank Tom.

Where's your gas tank located? Anywhere near the amps?

rscecil007 · Post by **rscecil007** » Thu May 06, 2010 8:35 am

stipud wrote:
rscecil007 wrote:
stipud wrote:Where is your fuel pump located? Any wires near it?
The fuel pump's in the gas tank Tom.
Where's your gas tank located? Anywhere near the amps?

Not even close, amps is under the front passenger seat, gas tank is behind the cab of the truck, under the bed on the drivers side.

Thanks for the suggestion though. Ironically I read about a fuel pump causing a guy noise issues on diyma this morning.