Bass sound from my speakers at startup...HELP!
 

I have a 2103 Honda Accord. I installed a pioneer 4 channel amp, 4 speakers. I used a PAC LP&-4 Line out converter as I kept the head unit. Right now every time I start my car I get 4 loud bass noises, it appears each of them comes out of a different speaker. They are quite loud. It happens once at startup and then never again. Any ideas? I get a whuuump whuuump whuuump whuuump and then it is done.

Engine noise
 

Read this it can be varoius things.


https://www.crutchfield.ca/S-YHGkbGxoSaG/learn/learningcenter/car/noise_suppressors_installation_guide.html