I own an 85 eagle stationwagon. The manufator speakers in the car, since so old, are horrible and would go in and out and would raddle. Yesterday my brother and I went to Walmart and got 60 dollars worth in 4 new speaker, no specific brand just cheap ones. We installed them at my dads house which is out of town on a bumpy dirt road. We tested each speakers TWICE, once before we completely installed them and then once again once it was installed. ALL were working completely fine and it sounded great!! When I went to drive home last night on the bumpy road the left (driver's) side speakers were going in and out!! Now that I'm back in town they work but EXTREMELY quietly and if I turn them up really loaud which is not loud at all since they are quiet they are very distorted. What is happening and how can I fix the problem??
Check your connections to start with since you stated their going in out. See if the wires are still properly connected. Consider soldering the speaker wires if it seem that this is gonna be an issue.
I assume your head unit (radio/cd/tape player) is stock?