I just put in a 400 watt amp with a JL 8 inch sub. The problem I am having are the sub works great when the car is not running but when I start the car the sub will not hit at all. Then when I shift to neutral the sub hits but it makes sound like something is rolling around in my trunk. The amp is not going into safe mod so I ahve no clue what is going on.

 

What is your amp's remote wire connected to?

 

The remote wire on the deck, its a kenwood deck.

 

hmm. this is intersting.

sounds maybe like the engine is drawing alot of power when it is in gear, causing the amp to drop its power levels. but it should be fine considering it can run off the alternator.

i am very curious to what the problem is

 

plz tell me that you have your +12v wires runing on one side of the car ans your audio(rca)wires runing on the otherside... also take a picture of how you have the amp wires hooked up on the stereo

 

i second that.

 

i had a similar situation. all i had to do was replace the rca cables. good luck

 

The rc, remote and power wires run under the carpet and the speaker wire to the amp is run by its self under the carpet to the trunk. The remote wire is connectced to the deck with a crip connector. The ground is bolted to the passanger seat mounting bolt.

 

run the rca's separate from the power wires. this most likely isn't the problem but did you make sure you had bare metal under the ground (no paint)?

 

No I didnt but I was going to check that. Yeah the RCA cables are taped to the remote and power cabe, this is how the stereo place put them in. This wasnt a problem before I put the amp and sub back in. I had the system out for about a year and am using a diffent am and a new ground point from the last time.