so i had a split in one of the plug wires so i ordered a set of motorcraft plug wires on ebay part number WR-5791 and now after i installed them i have a hum that comes through the speakers even with the stereo off. seems to be loudest at the end of each gear and around 70 mph.. the old wires were bosch premium but the WR-5791 from motorcraft should be the stock replacement i believe.. what would be causing this hum? its a 97 xlt super cab 4.0 v6

 

You probably disconnected or ripped the wire to the noise canceling capacitor. I know of the 2.3/2.5 4 bangers the wire is right next to the coil packs.

Check for a loose wire or connection around where you worked in the engine bay.

 

If you did plugs too, it could be them.

 

i found it.. when i ran the wires i tried to get them to not touch each other to avoid cross firing at high rpm (read that in my vw beetle idiot guide). the #6 wire had slack in it and i didnt want to just wad it up into that cave passing through the intake so on the plug side i had it loop up toward the firewall.. guess that loop was too close to the speaker wiring so now that cave has a wad of wires in it.. thanks for the help fellas

 

Hello I did the same mistake but after reading thread I have solved it. Thanks to all