tweeter buzz problem with bass notes

i bought a pioneer ts-ac173ci component set of speakers last week and had to custom wire them so that they would work on my car. i connected the main speakers perfectly and they work fine however after wiring the new tweeters to the original connectors they made a buzzing sound with bass notes and i could only use half of my volume before they would make this noise without any extra bass from the EQ on my car. any ideas ? both of them made the same noise