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Persistent Engine Noise


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Fosgate3 
Copper - Posts: 328
Copper spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: January 29, 2004
Location: Louisiana, United States
Posted: April 06, 2007 at 10:55 AM / IP Logged  

Okay... this is long but I want to be thorough so everyone will know what I did and did not do. Here's how it has gone so far this morning:

I pulled out the HU this morning and connected my mp3 player up as a source. When I did this before, like a tard, I left the Pioneer HU connected in order to get the remote feed. This time, I tapped the remote feed into another 12v source to get the amp to turn on. When I did this, I still had noise. Next I took a pair of plain-jane RCA's (instead of the streetwires that I had) and ran them outside the vehicle to the amp. No noise. Of course, I could only run one set at a time so I just ran everything into the rear first and then the front... no noise at all. After that, I pulled the 860MP HU from the truck and used it with the plain RCA's.  That checked out okay. I tried the new 590IB unit and that checked out fine too--I didn't hear any noise in the system. During this check I was only doing either the front or the rear channels, but not all 4 together. From that point, I stripped everything out the car, pulled the streetwires and tried the same thing with them. I was thinking that either the RCA's were faulty or I made a mistake by running them through the middle of the car under the console. What I found was that the Streetwires produced noised without having them hooked up to the HU, as odd as that may sound. I just held the RCAs in my hand and noise was produced. Without using a HU, I did the same thing with the cheap plain ones (and thought back to an earlier reply to this about how someone goes with the cheapest RCAs he can find) and the cheap ones did not have noise. Again, I was connecting them to one channel at a time. So, I decided to run the plain ones and not the Streetwires. I did that, both sets all the way to the front, to the hood release. I kept the car running while I did this and had both sets (all four channels) connected,  just to listen in case noise popped up. When I got to the hood release, I connected them to the 860MP HU and low and behold, there was noise.

After cussing a bit, I moved the RCA's out from where I just ran them. I noticed that depending on where I held the RCA's (this is all on the drivers side), the noise grew louder and would return to the normal volume... strange. I was thinking it was interference from something but I couldnt think of anything that would cause that. I went an rechecked the RCA's one set at a time and found out that both sets were fine... on the rear channel of the amp. However, when I plugged in the front side after the rear were already connected, noise was produced out of both front and rear speakers. I disconnected the front set from the amp, the noise went away. I swapped the RCAs at the amp and everything was still cool though I kept thinking I was hearing a nearly inaudible hum. When I connected all four channels back, the noise returned. If I kept just the rear connected to both the HU and the amp and the front connected to the amp, the noise was there. This happened no matter what set I used on the front. Noise was present regardless. This also happened if nothing was on the rear but the front was connected AND the amp's "signal source" switch (I call it that b/c I dont have another name for it) is switched from using both Front and Rear signals to using Front only. If set on using Front and Rear, the amp works without any apparent noise on the EITHER the front side or the rear side BUT NOT when all four channels are used.

I tried grounding the shields of the RCAs. That made the noise worse. I did this at the HU. I did not go back to using the mp3 player as a source b/c with it, I could only do one channel or the other and I already established that the rear worked great but the front side didnt. Also, I tried using an PAC SNI-1 on the front channel when all four channels were being used but that didnt do anything. 

So... what now? new amp? It is a coincidence that I had such a similar problem with the Rockford 551x. I ended up having to bridge everything off of one channel until I could get a different amp. If there is a problem in the amp, is something I could look for and fix?

roo-dog 
Copper - Posts: 124
Copper spacespace
Joined: January 17, 2007
Location: United States
Posted: April 06, 2007 at 3:23 PM / IP Logged  
  i wouldn't rule it out, but i doubt it is the amp.  If possible, i would try a non-pioneer head unit.  anyone you can borrow one from?  i am a big pioneer (head unit) fan, but i keep hearing more and more about them producing noise through the rcas.  i, myself have had this problem- even now, i have a little bit of noise, probably coming from  my 860mp.   noise sucks!
(4)g5-1244, (4)gtr12, (2)ppipcx2400, (1)pcx4125, (1)pc4800.2, (3) pair mb quart 6.5"Q, (4)optimas, alumapro (1)5 and(1)15 farad cap, premier deh-p860mp, pioneer xm -dual H.O. alternators
Fosgate3 
Copper - Posts: 328
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Joined: January 29, 2004
Location: Louisiana, United States
Posted: April 06, 2007 at 4:40 PM / IP Logged  
noise sucks a lot. I am trying to get a Denon unit from a friend and if all else fails, I'll snag my wifes Clarion and use it to test. I should have a chance to do that tomorrow.
Fosgate3 
Copper - Posts: 328
Copper spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: January 29, 2004
Location: Louisiana, United States
Posted: April 14, 2007 at 10:08 AM / IP Logged  

Update...

I got a new head unit, a new Clarion DXZ665MP from last year's line up. I wired it in this morning and the noise is still present with no change at all. So now, given that it has noise with two head units, both new, and with several sets of RCAs regardless of brand or anything, I'm leaning towards the amp. Does anyone else have any ideas?

Fosgate3 
Copper - Posts: 328
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Joined: January 29, 2004
Location: Louisiana, United States
Posted: April 15, 2007 at 6:52 PM / IP Logged  

I rerouted the RCAs on the passenger side of the car, well away from any factory wiring. That didnt change a thing. I also noticed that the noise gets louder if the rear gain is turned up. The noise is still present when the gain is all the way down too, just not as loud. I can turn it up about halfway before the noise begins to get loud. Everything is being run off the rear channels of the amp b/c the when both the front and the rear RCAs are connected to the inputs of the amp, as stated before, the noise is quite loud. I noticed that the front gains do not seem to affect the intensity of the noise like the rear RCAs do. I plan on testing a different amp in the car later in the week.

Does anyone think a run of 4 guage cable from the negative post of the battery in the trunk to the alternator casing under the hood would accomplish anything? I was considering that as well as moving from the point on the casing that the cable attaches to a factory ground point I found on the engine block.

DYohn 
Moderator - Posts: 10,741
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Joined: April 22, 2003
Location: Arizona, United States
Posted: April 15, 2007 at 10:19 PM / IP Logged  

1.  Have you measured your amplifier and HU ground return values?  Are they ALL less than one ohm?

2. You may need to change your attention to your vehicle's electrical system.  Check for broken insulation on spark plug wires, cracked distributor cap, bad ignition coil, cracked insulator on a spark plug, bad plug, bad ground on your ECU, bad ground on your fuel injection system (if the car has EFI) etc.  If the issue is in the ignition system nothing you do with the audio system will have any effect.

3) Have you gone hand-over-hand on every inch of all speaker wires to make sure one or more is not shorting to ground somewhere?

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Fosgate3 
Copper - Posts: 328
Copper spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: January 29, 2004
Location: Louisiana, United States
Posted: April 21, 2007 at 9:45 AM / IP Logged  

I have a headache.

I finally got my hands on a 2nd amplifier today, a PG XS4300. I changed it over and noise is still present. I decided to start over in troubleshooting at this point and re-examine what was going on. So, I took the xs amp and wired it up to the battery with amp just sitting in the trunk. The battery in this car is in the trunk so the run of power cable is about 15 inches or so and fused of course. I didnt use anything I ran in the car. For the signal, I used my mp3 player and some F-to-M Yadaptors and connected the mp3 player to all four inputs. The mp3 player also just sat in the trunk about a foot from the amp with the signal cable lying on the floor of the trunk as well. Test speaker was a 4" Altec Lansing (like that matters). No noise at all, sounds beautiful. So, Question #1 is "Does this suggest that the charging system is okay if there is no noise in this first phase of testing?"

Next I kept the amp and power the same but then used the RCAs in the car that I ran. Noise was present. So, I pull the radio and disconnect the RCAs from the back and noticed noise was still present, more so in the Rear set than the Front set. I then ran a set from only one output of the radio outside the car, over the two open drivers side doors and into the Yadaptors at the amp. I still have noise, at the same minimal but present manner that it had been at. I went to do what DYohn suggested in his post, point#1. In fact instead of just measuring it, I went ahead and clipped the Clarion's ground wire and ran a new one over the seats to the amp and grounded it with the amp. Still have noise.

So, by this point, I'm grasping at straws. I decided to see what happens if I moved the RCA that I ran outside the car from where it sat draped over the doors to moving it to the roof. Magically, the noise went away. When I moved it back, the noise returned, still at its same level. Since I cant drive around with RCAs flapping in the breeze, this really doesnt help me any. I also tried to see what would happen if I bridged the speaker to the amp instead of having it stereo. When I did that, the noise went away but there was a feint buzz. I tried then to use the already-run-RCAs without even connecting them to a source and the noise was feint in the Front set and much more significant in the Rear set.

By doing all this, I have eliminated DYohn 3rd suggestion and depending on the answer to the "Question#1" above, the 2nd may have been taken care of too.

I'm at a loss and am losing my confidence in my ability to install at this point in spite of all the years I've done this successfully. I keep thinking of DYohn 2nd point and the first thing that comes to mind is "this is a brand new car and none of that should be going on". I dont know...

Fosgate3 
Copper - Posts: 328
Copper spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: January 29, 2004
Location: Louisiana, United States
Posted: April 21, 2007 at 9:52 AM / IP Logged  
Oh yeah something stupid I noticed during the week while at work: It got pretty hot in the car a few days during the week and when I got in the car at some points and took off for one place or another, I noticed that there some times when the noise wasnt present. This was only in the heat of the day. In the early morning hours, it was still there all the time. So whatever that means here... ?????
demon_510 
Member - Posts: 23
Member spacespace
Joined: March 05, 2007
Location: United States
Posted: April 24, 2007 at 2:44 PM / IP Logged  

There are multiple ways to introduce noise into your system.  I am not sure if any of what I am about to say has been tried since I dont feel like reading your whole post but here are some ways to troubleshoot it.

If you have a nasty engine whine first I would do is to check if it is infact engine whine, is it whining while the motor is not running?

Check your grounds first, take a magnetic tape head wire it in series to a mini jack and plug it into a self powered speaker (found at radio shack) turn the speaker up and place the tape head over the grounds and listen to them, if you hear a lot of whine then it could be the source of your troubles.  I like to listen to the chasiss prior to utilizing a grounding point.  This tape head is also usefull for routing RCA's and power wires (yes I was an member of autosound 2000 a long long time ago for those who remember this).

Fosgate3 
Copper - Posts: 328
Copper spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: January 29, 2004
Location: Louisiana, United States
Posted: April 24, 2007 at 3:00 PM / IP Logged  

That thing with the tape head... that's interesting. I'll check it out. You'd have the car running while doing this I'd guess, right? Head unit on but volume down to zero?

Oh and yes, the answer to the first question is "no". With the engine not running, there is no noise. The noise seems to fluctuate with the temperature?? as crazy as that sounds. It's more prominent in the mornings, less in the afternoon. It's very loud in the morning until I turn on the mp3 player. Since I listen to hit nearly all the time, the HU is left on it's Aux setting when I park the car.

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