Car shutting down at stops after install, but not electrical power?

[crreed55 10+ year member]

I have an 07 Mitsubishi Galant with 90k. I recently had two subs, an amp, and a head unit (had to use a dash kit adapter too) installed by a local audio place (who's usually very good at this stuff).

After it was installed, my car starting "pulsing" and rumbling, and there was a noise coming from behind the steering wheel (almost like a static white noise), but that disappears when I apply the break. It also has died several times at stop signs and stop lights.

I took it back, and they tested the battery and said I needed a new one (it was only 2012, but it was leaking acid), so I bought a new one (high performance, more power than the base), but nothing changed. I went back again and they did some more tests on it, and told me to clean out the fuel system because one of the employees had a similar problem after getting gas from a Henny Penny (where I last got it), so I bought a 6 oz bottle of Gum Out (which they reccomended), and it hasn't helped much. It pulsates less and hasn't died, but the noise is still there and it's definitely still pulsing, especially when stopped.

There's a "service engine soon" light that came up after the install, and the code was for "engine misfire".

I don't think it's an electrical problem because:

1) when it dies, just the engine shuts off; the lights, stereo, etc. remain on

2) the car did not have any electrical or mechanical problems before, and even though I have a new battery AND the amp/subs are disconnected, the problem's still there

But I'm convinced it's because of the install, as none of it was a problem until then.

Has anybody had a similar issue or know what this might be? Thanks

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[CrossoverOre 10+ year member]

double check all connectors, plugs, wires, everything along the power wire run under the hood. Make sure no wires were messed up and all plugs are snug. I would also check everywhere else under the hood as well. Was the a specific cylinder misfire or all?

 

[los33]

Well the most the install could have done if it was grounded incorrectly is blow one of your relays or destroy a computer or anything.

Without the codes no one could tell you as mitsubishi is made to be fully computer reliant so we need codes.

Few reasons this is happening is:

--fuel relay or any relay is going bad

--fuel sending unit is going bad (fuel pump)

--bad ground or wire exposed and touching metal

--fuel filter is clogged up

--ECU is half way fried