I searched the board already for other threads about engine noise coming through the speakers but nothing had the twist that our issue has.
When the engine is off the stereo works wonderfully! When we turn on the engine it works fine and then as we accelerate we randomly get engine noise in the passenger side in boat speakers. If I flip the accessory, navigation, or anchor light switches the noise stops 85% of the time. The nose will come and go when we hit choppy water and at different RPM levels. When we are going slower (no wake zones) the noise is far more consistent but we don't have the sound every time we are going 5mpg.
We just installed 2 new amps (removing the old ones) new tower speakers and ran new 14gauge speaker wire to the 4 in boat speakers but not to the tweeters. Here is our set up:
Alpine PDX 5 runs 4 Alpine Type R 6.5" component speakers and 1 JL Audio sub
Kicker ZX 450.2 running the KMT 6 speaker pods on the tower
Sony head unit with iPod direct connect and 2 Sony RM-X55 wired remotes
We always listen to the iPod and that is what we were listening to today when we had the problem.
Our guess is that it is a grounding issue but we can't figure out where the grounding issue is. All of the connections are tight and we are running power and ground from the battery at 4gauge into a power distribution block with 8gauge running out of the distribution block to the amps.
Again the engine noise is only in the passenger side in-boat speakers and it is intermittent.
It's really hard to diagnose the problem here at the house since the engine is not running.
(Message edited by shepsigkap on May 17, 2009)