Persistent Engine Noise

Yes the car would have to be running, but the audio equipment would have to be off.  A possible reason why you might have more noise in the morning could be due to you alternator working a little harder warming up the car and charging your batterie/s. 

Do you have any grounds or positive wires crossing your RCA's or positives really close to your grounds?  You can also try to ground your HU where your amps are ground to and see if that eliminates your problem.  Do you have a passive eq or active x-overs?  I was running some Rane Eq's and they were a little on the noisy side till I grounded them to where my amps grounds.

Oh, and you might have issues with your RCA's and the path they are routed if you are taking an RCA and running it outside of the car, see if you have any grounds or power leads running next to your RCA's.  If noisy RCA's are the issue you can always run some steel braided sleeves over them and ground them the reverse direction of your signal flow.

I forgot what Hz alternators operate at but if you have a large cable going from the alternator to the battery then you have a huge potential for inducing noise into your system.

If you are located in the Dallas area I would be money I can find your problem within an hour.  I dont work at a shop anymore or work on systems except my own but I am always willing to look at some work and help with troubleshooting.

I'm about 4 hours from Dallas in West Monroe, LA. heh... if I cant figure it out, i may look you up!!!

I'm pretty certain there's a cable from the battery to the alt... that would only make sense. I wonder if re routing the cable (likely re-running it with 2 gauge) would help.

The alternator is a possibility that I havent forgotten but I've been postponing that until after I've tried everything else. Demon's comment about the power wire running from the alt through the car to the battery made me think "well duh! that makes sense!" And as Demon said, it may be b/c the mornings are when the alt has to strain the most to charge the battery so the whine is more intense at that point. Since the power from the alt is carried through the car from the front of the car to the trunk, then any alternator noise created has the potential to travel along with it. Thus, if the theory stands, anything carrying a signal en route to the battery is suspectible to be a carrier of the noise too. ... and of course, this could be completely off base and I could be wasting time looking at everything else but the alt.

Yesterday evening, I tested some aspects of this idea and ran a set of RCA's along the roof of the car, on the passenger side to the processors under the passenger seat (eclipse 2101 --yes i know it's an eq-- and AudioControl ESP-3). The input to the processors stayed routed the same way... just the output to the amp was changed. Doing this made a significant difference. In fact, I was able to use both front and rear RCA inputs on the amp with nearly non-existent noise. I had to strain to hear it in fact. That minimal amount couuld be resulting from how the input signal is run or something in the processing. Still, it was more than tolerable and could be considered successful. The idea was that if the alt cable is potentiall carrying noise, then running the signal as far from it as I can could alleivate the noise. What was more was that I pulled over on my drive home and was able to turn the gains up on the amp which I couldnt do before without significantly increasing the noise.

This did well until I arrived at home and turned off the mp3 player while the car was running. When the player was off, the noise came back very loudly. When I turned down the radio, the volume of the noise subsided. The gains on the amp are not much higher than half way (about 2/3 to 3/4 on the front and between 1/2 to 2/3 on the rear). So this time, I'm thinking input RCA routing still needs to be adjusted or turn the gains down on the amp which would suck since I'd have to turn the radio almost wide open to get what I want. I'm going to start by testing different runs with the input. Also, I'm going to reroute the power cable going from the battery to the alt from where it is now goign through interior of the car to running it along the frame on the underside shielded in conduit. Since the factory wiring looks to be 6 gauge, I'm going back with 4 gauge ofc cable (20ft by KnuKonceptz).

I've made some progress in this: Using the 8 gauge power and ground that I ran from the battery in the trunk to distribution blocks in the center console (see a previous post a couple of pages back), I grounded not just the radio, esp, 2101, and srk5 to it but also connected the cigarette lighter receptacle in the console to it. This is the receptacle that my mp3 player connects to. I clipped the factory wires and capped them off then ran replacement wires from the receptacle to the distribution block. Secondly, I ran the RCAs through the headliner and down the side wall where the seat belt is on the passenger side, to the processing equipment. All this made a significant difference in everything. The noise is at a very minimal, tolerable level--considerably better than anything that I've heard in the car prior to now.  

My next step is to rerun the main power cable from the battery to the alt, as I mentioned above. I received my order of 4gauge cable and will run it this weekend under the car, secured to the chassis, all the way to the passenger side (as opposed to the factory cable running through the middle of the car, inside the car). Then, I'm moving all the processing equipment to the drivers side (it's under the passenger seat now) as well as my RCA cables, routing them through the headliner as before.

Bit by bit, its coming.

I've already bypassed everything in the car several times now and have run simply the different HU's and amps, even the mp3 player (minus the cigarret lighter) as a source. At this point, I've done this with multiple amps, multiple HU's, multiple RCA's, etc. I put the "other processing equipment" in just b/c I know it's not the problem as the problem existed without, didnt change with it. I can go back and do it all again but it's not going to help. The only thing thus far that has made any difference at all is what I just wrote: moving the RCA's through the head liner, well away from the factory 6gauge cable that runs from the battery to the alt, and redoing the ground for the 12v point that the mp3 player's charger plugs in at.

Yes, for the meantime, it is 8gauge which is suitable for amp that wont draw more than 40amps of current (in spite of the 50amps of fuses) for mids and highs.... especially on a 5 to 6 foot run. Eventually it will be stepped up to 4 gauge when I add a distribution block and the two Kicker DX700's that I havent started on yet. Gots to fix this first issue *wink*.

As far as the first point made for DYohn, I wish it was that simple for me.. I probably would have identified it about 2 wks ago before I ever made the post. Unfortunately, this is intensely complex. But yes, as stated, I've eliminated all in-between stuff. thinking back now, I dont think I posted that I got my hands on a 100% working PG XS4300 and put it, the mp3 player, and a set of RCAs in the trunk of the car with the battery. The XS was wired directly to the battery. The mp3 player was running off it's own battery, not using the car charger or anything. The RCAs were coiled up on the trunk floor. No noise. I kept the amp where it was,  used the same RCAs but moved the mp3 player through the car to the front,  had noise. Continued to have noise with the HU (just as before) with the same amp. So, that pretty much elminated the amp, I'd guess. I feel it did anyway. *shrug* I dont know...