soundman98

so my car has a whine when the engine computers are energized.

the whine is only present when the car computer(the car ecu, not my pc) power up, and is there wheather the engine is on or off, but when the key is set to acc. and the engine and engine computers are off, there is no whine.

i have tried ground loop isolators on both the power and ground for my smaller draw items(a preamp before the amps), but neither worked.

i have tried combining all of my amps to the same ground point, and have moved my usb sound card to the trunk within a couple of feet of the amps, and have also tried different rca cables, but the noise is still present.

currently, the only thing that i can come up with is that my power cable runs next to the factory wire loom along the sill panel, and the noise is getting picked up by this cable.

if it helps, i have a total of 3 power/ground points for my setup, the monitor is powered by the factory radio harness, and is grounded in the radio bay, the car pc is powered through a separate run of 8 ga wire directly off the battery, and is grounded directly below the radio, to a factory ground point, and all my amps are powered off a 4 ga cable also coming of the battery and are grounded in the rear of the car, on the drivers side.

any ideas?

MP3Car.com

 

jake789

One thing you can do is check your grounds. Get a cable around 20ft. Attach one end to the neg terminal of the batt (reference ground). Then with a voltmeter, check to see if theres any potential voltages on your (amp and carpc) ground points. Just put one dmm lead to the ground point and the other to your wire.

If you see any voltages or most importantly if the two grounds read differently, then you might have a bad ground.

Did the isolators help at all? Any change?

Maybe try grounding the rca's if the above doesn't help?

soundman98

i will definatly check it out.


the isolators did not change anything(although i was unable to use them on my amps, so it could stil be a ground issue), and grounding the shield/negative lead of any of the rcas results in sound on all speakers, something like a 900-1khz test tone-- at a higher level than normal listening volume(now that i think about i, i will also have to check the rca- to ground with a dmm too).

da_glu

it it possible to re-route all the cables so they're as far away as possible from the ecu and any other of the car's electrics(i had a similar problem with my car and after moving the cables i didn't even need isolators)
hope it helps
neil

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soundman98

i beleive that my power wires are picking up the noise- from running next to the factory harness the lenth of the car(or i have a faulty ground), but need to do alot more testing to know for sure(my sub amp ground showed 100 ohms, but devices connected to the same locations-for power and ground read 2-4ohm average).

MP3Car.com