Fronts distort only with engine running

Hi everyone, I'm new here so please bare with me.

At the moment I'm running 2 Koss 3-Way 6.5"'s for front speakers and two 10" subs in the back powered by a Sony Xplod 1000W (max) amp. My deck is a Sony... pre Xplod which puts out 45W max x 4... the fronts are running right off of the deck.

Only recently has this problem cropped up: when I'm running the van it sounds as though there is a weak or intermittent connection to the fronts causing clipping which doesn't sound like EMI at all. I turn off the vehicle and they sound fantastic.

Any ideas? Thanks in advance.

prolly the deck....good ol' sony does it again!.........it could be a ground gone bad or one of the other power conections, but given sony's track record I would bet that the deck has gone bad

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if its jammed force it - if it breaks in the process it needed to be fixed anyway

check your ground to the amp...could also be an open ground on the audio path for the front RCA cable ( in the HU )

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Kevin Gerry
Certified Electronics Technician
MECP First Class Installer

Owner/Installer
Classic Car Audio
since 1979

The fronts are running directly off of the deck. Would this really indicate that the deck is on its way out? It is fine when the vehicle isn't running.

You may only hear the problem in the fronts because of frequency.  Check the ignition out thoroughly.  A good suggestion that DYohn has made is to drive to a dark place at night, open the hood, and with the engine running watch for signs of spark  or light along the wires.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Oh wow... that would sound like a more serious problem with the vehicle itself. If I do see sparks, do I need to have the ignition replaced/overhauled?

No, perhaps a loose wire or a pinhole.  But take it to a mechanic if you do see such signs.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Thanks... I'll also check the power connections to the deck... but wouldn't something of that nature cause the deck to lose power?

Not necessarily.  A power connection can be unstable but still partially connected.  First, eliminate the ignition as problem source.  That done, then check connections and go from there.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Alright, again thanks. I've got to wait for the sun to go down; then it's off to try and see sparks... (hopefully not see them)

...(hopefully will see them)...eliminate problem on the first check?  Everybody's dream!

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Well... I didn't see any sparks whatsoever. I guess it's off to chase loose/intermittent connections. That is unless there are other possibilities here?

Thanks.

Did any of your wires seem to glow?  (you have to be in a really dark area to see this.)  The most commong causes for engine noise like you describe are problems with electrical system wiring (like bad sparke plug / coil / engine ground straps, cracked distributor cap, etc.) or bad head unit ground.  You might try running a new ground lead for your head and not use the fatory ground lead.  Also, make sure none of your speaker wires is damaged or touching ground at a connector.  Good luck, the problem you have is one of the hardest to track down.

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Thanks DYohn

It was pitch black when I looked but I didn't find anything at all. I'll try running a new ground wire to the head unit, but it did seem to test fine giving me about 12.51 V.

This isn't going to be fun, I can tell already. Thanks again.

Ground should have no voltage on it... but it's noise you're after, not voltage.  Try running a new ground wire directly to the chassis (bare metal on the floor pan, not to a screw under the dash) and connect it to the head unit ground instead of using the factory wiring harness ground.  It's a shot in the dark, but it is the easiest to do.

Now, did this system work fine before and then suddenly develop the noise??  If so, you will probably have to buy new spark plug, plug wires, dist. cap, rotor, coil wire, etc. because that is a much more likely source for the noise.  COMPLETE electrical system tune up, but that's only about 50-50 that it's the problem.  Also check the engine ground strap between the motor and the chassis (it's usually a flat braided cable) as it can get corroded and cause this problem....

No, this one is never fun and it can get darn expensive to find and fix.  I wish yu luck.

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