Strange engine noise problem?

[The Lord Flashheart]

I had an annoying alternator noise that was finally cured by placing a choke on the front amp power cable near the battery. This is just 10” of wire wrapped around a 1.5” dia. ferrite core multiple times.
Also had tried installing a 5uf polypropylene cap on the alternator, grounded to the case. While that didn’t do much to help the obvious noise, it improved the sound quality.

Before this, I had messed around with different power/ground schemes and nothing made a difference.

Hi Phase,

Would you mind elaborating on these please?

Is the choke made with the power wire itself?

In what way did the cap improve the sound quality?

I am thinking the buzz related to the brake and indicator lights could be cured with an artfully placed cap so I'm curious.

 

[phase]

The choke was made with ordinary stranded 10AWG cable, wound tightly to the core, and held in place using a couple nylon cable ties. Crude, yet effective after changing many things that are touted as fixes for ground loop problems. Still a good idea to clean and re-tighten all of the charging system connections out under the hood, even the ground straps, ground lug for the fuel injectors.

The cap on the alternator was a blanket improvement, tighter bass, more clear mids and treble(more softer detail). Highly recommended, and hope it allows for the same effect as I had experienced. The part was a box (.5” X 1” X 2”)shaped part from Epcos that came out of our dead microwave oven before I sent it to the dump.

Another thing that I had changed was to use a more-dedicated power wire for the head unit, instead of the factory wire that was on the same circuit as a bunch of other stuff. That eliminated some odd random pops and clicks on occasion, and gives slightly better treble.

 

[The Lord Flashheart]

The choke was made with ordinary stranded 10AWG cable, wound tightly to the core, and held in place using a couple nylon cable ties. Crude, yet effective after changing many things that are touted as fixes for ground loop problems. Still a good idea to clean and re-tighten all of the charging system connections out under the hood, even the ground straps, ground lug for the fuel injectors.

The cap on the alternator was a blanket improvement, tighter bass, more clear mids and treble(more softer detail). Highly recommended, and hope it allows for the same effect as I had experienced. The part was a box (.5” X 1” X 2”)shaped part from Epcos that came out of our dead microwave oven before I sent it to the dump.

Another thing that I had changed was to use a more-dedicated power wire for the head unit, instead of the factory wire that was on the same circuit as a bunch of other stuff. That eliminated some odd random pops and clicks on occasion, and gives slightly better treble.

Thank you for taking the time to post, that’s very interesting and I shall try the cap and report back.

 

[The Lord Flashheart]

To close the loop on this thread, the noise mysteriously disappeared when I put the head back after checking the wiring over.

I think it must have been a sketchy ground somewhere around the HU or the Canbus adapter box and jiggling it about seems to have fixed it.