amp increases with engine on

2003 Toyota Sequoia w factory JBL Pioneer TS-SWX251, Boss R1100M mono amp w 4g wire. Rear speaker wires were spliced under the center console and run to the amp at the "high level inputs". The set up can either sound good with the engine off or sound good with it running but when the engine is on the sub level increases dramatically. It does not change with RPM. This seems like a bad set up (everything that has to do with the Boss amp at least), would the best thing be to get rid of that amp or could something else be the problem? I have heard of a lot of problems with these amps but not this particular problem. Thanks in advance!

Did you go straight to the battery for power? Where and how did you ground? And what wire colors did you use for the high level ?Gary Sather

Is the radio equipped with Speed Controlled Volume? Is there a way to turn it off?

Maybe the jump from ~12.6V to 14.2V? (Almost 30% extra power.) Plus both above replies.

Either speed sensitive volume as IAAI suggests, or the OEM subwoofer which only operates when the car is running.Support the12volt.com

Thanks guys. Power is run straight to the battery, It is grounded about a foot away to bare metal but the ring terminal is under the rear factory amp mounting bracket. There is no speed controlled volume or factory sub and sound does not increase with speed or RPM. Only sub increases. The wires are spliced in at the factory rear amp large harness, RD, BK, WT and YW (1,2, 8 and 9 on harness). They routed everything under the center console and under the passenger seat to the amp. Power wire right along with speaker wires to the amp. I was thinking, could this be an engine noise issue coming off as an increase in sound? It doesn't really buzz or hum or whine but it is definitely louder with engine running. I turned it off and on several times yesterday trying to hear a difference and it seems to get louder after the vehicle is driven awhile and then stopped. ACC to engine running= not very noticeable After driving the vehicle for some time and parking, shutting the engine off=sub level seems to decreases significantly. I have a line level converter, would hooking that up and using patch cables be worth trying? Thanks again for all the help!

You are missing one add-on and that is a capacitor that will give you the right volts to the amp all the time. Sounds like you get a power surges from your system that feeds it to your amp.

A capacitor is not needed nor would it have any effect on the system. What is system voltage at the amp? How does it change with the changing engine status? Could simply be what oldspark suggested: battery volts VS alternator volts and a poorly designed amp.Support the12volt.com

longboy64 wrote: You are missing one add-on and that is a capacitor that will give you the right volts to the amp all the time.

That is just so wrong! A capacitor never has a voltage higher than the battery. (At times it will be lower.)