Engine noise problem. Please help

[doosra]

Hey guys,

Need some advice.

Basically I had my system set up and it was working fine and then all of a sudden the head unit went off while driving. I pulled the dash apart and seemed like a loose wire so I checked all cables were secure and put it back and it's working now except I have a lot of engine noise.

Things to note:
- rca's are run on the other side of the car opposite to power cable going to amp.
- ground cables are short and secured well and are on bare metal surfaces.

No changes to the setup but just way too much engine noise now.

I'm at a loss of what could be wrong.

[doosra]

I've been doing some research and I'll try grounding RCA's tomorrow which I think will work. If this is the fix, does this mean the head unit is faulty? Should I claim warranty on it?

[TbM]

what headunit are you using?

[doosra]

Jvc avx746

[TbM]

Jvc avx746

Damn if its not a pioneer (they have history of rca ground being faulty) then i usualy check and redo grounds if problem persists test other set of rca's (just plug in back of headunit and run over carpet too boot) if this fixes the problem then your rca's may of been damaged. if problem persists then i look at grounding rca's.

ive also had engine noise come from the speaker terminal intermittently contacting the door skin and causing a short/ground loop but if its only just happened i doubt this is the cause.


the headunit turning off then the problem happening indicates a bad ground to me imo. Is your headunit ground using the stock ground or is it grounded to chassis?

[doosra]

Headunit ground is to the chassis. Weird thing is nothing's changed in the setup or where the ground is and I'm using good rca's as well. I bought the kicker amp kit which was $100+

[TbM]

you familiar with rca shorting plugs? (also called rca dummy plugs iirc)

you can use them to help diagnose if the noise is from the amp or headunit.

[doosra]

Okay, so I grounded tune rca and it got much better but there is still an annoying ticking engine noise.

The difference I found once I earthed the rca's is that the engine noise was no longer consistent when you put your foot on the throttle and sound volume was more louder. The noise does however react to window wipers.

One other thing to note is that when the headunit is half out of the dash, very minimal engine noise, if any, but once you push the headunit back into position against all the other cables, the noise gets louder. Seems like interference of some sort.

I'm gonna try to find another set of rca's to test as I noticed the noise was more prominent on one of the pair's of rca's when plugged in.

Any other thoughts?

[doosra]

I've narrowed down the problem further. So much current set up is:
Kicker - 4ch amp
Kicker - component 6" front
Alpine type r - 6.5" rear.

What I've found is the sound is coming through the kicker tweeters only and only appears when the gain is up past 1/3 of the way. If you minimize the gain then the noise disappears.

The gain on the rear alpines can be turned up as high as possible with no issues.

Any thoughts on this? Only happened recently. Not sure if it's amp, hu or rca.

Not such a big issue now as I can minimize the gain but would prefer to be able to have the gain on component speakers higher though