ENGINE NOISE COMING OUT THRU MY SPEAKERS - Jl Audio 300/4 Car Audio Amplifier

I would first check the computer for trouble codes. The speedo problem could be the speed sensor in the transmission.

Often this is alternator noise. Stop by a car stereo shop, they have a bolt on piece that can help suppress the noise. Be sure to verify good grounds, or you get transient currents and noise.

may be that it haves a lot of dust were you plug in the cable

It ur Vizio tv,The power supply board is the problems.The transformers in the power supply board have gaps in the transformers.The high voltage curents flow that make that buzzing noise.

Change the ground wire. Make it as short as possible also.

I have same problem and I figure out that it's coming from transfomer. No I wi'll have to check how can I fix it.

correctly connected to output on tv ? ie red and white left and white and not yellow (video)??

this could be due to some static  please get your electrical point checked up 1st  is your tv hooked to watch television thru RF or AV please have the interlink cables if this does not help get back with more details

hissing soud is from the altenator ( not a big deal ) have a noise reducer installed or have the stereo rewired for it's power wire from a different location. Very common thing that happens by do it your selfers.

As for oil temp I'm not sure what it should be on thatcar but is it oil tem or oil pressure?

may be the ground of the rca or in your stereo. and many times in the inlet of the amp. good look.