Help me diagnose my problem(s) on a 2003 GT

[2K2 LS1]

I have a 2003 Mustang GT with roughly 180k miles on it.

The first symptom is the fact that in the morning when I start the car up the battery voltage indicator light wants to start out a little below the half way mark(10 volt range) and the lights are dim. This is with the car at idle around 500-750rpm. As soon as I get the rpm up to around 1k rpm the lights brighten, and the voltage meter jumps to around 13-14 volt range.

The second symptom is the car seems to buck/stumple at around 1-1500rpm range pretty much in any gear under load. And clears up after about 2k rpm range.

The last symptom is almost like a ground hum through the radio when the car is anywhere in the rpm's below 2k.

I have replaced 2 coil packs since buying the car 2 years ago, along with 3 alternators(finally bought the Duralast gold lifetime alternator), spark plugs, all pulleys, fuel filter, and pretty much all your general maintenance. SO my question is where all do I need to focus on this car, to get it ready to sell and get our of the Mustang market for some time?

[sickpony]

I would almost bet your alternator has the wrong size pulley. - have been through several parts store alternators on my suburban and it looks like I will be saving my pennies for a factory unit. I have seen several with wrong size pullies ( you have to swap yours) and even more with crappy voltage regulators

[2K2 LS1]

My instincts keep telling me it is the alternator, as I have had similar symptoms when the previous 3 went bad; but I have had this one tested at the Vatozone in Terrell and they said it passed. I would think if you bought a lifetime alternator; and have pulled it off a car with issues and your symptoms that you are describing to them make sense for a failing alternator. Then they could waranty it for you and see if that fixes the issue.

[Mysticcobrakilla]

I'm willing to bet that the hum you are hearing is caused by bad diodes in the alternator.

[2K2 LS1]

I'm willing to bet that the hum you are hearing is caused by bad diodes in the alternator.

How do I get Vatozone to exchange this POS?

[scootro]

How do I get Vatozone to exchange this POS?

Duralast gold lifetime warranty?

[mystic96]

Damn my '99 GT has been doing something similar since I picked it up a couple months ago. Not really the gauges jumping around, but my battery light comes on intermittently. Like if the light is on and I rev it up, the light turns off. Or if the light isn't on and I rev it up, the light will come on. It's never constant though....

I also have the miss/stumble/hesitation up to 2k rpms. It's pretty damn annoying.

From all I can find online it usually turns out to be a bad coil, but it's not setting off any trouble codes and tripping the Check Engine light.

I guess the only thing to do is go coil by coil swapping in a new one to see if it clears up.

[2K2 LS1]

Damn my '99 GT has been doing something similar since I picked it up a couple months ago. Not really the gauges jumping around, but my battery light comes on intermittently. Like if the light is on and I rev it up, the light turns off. Or if the light isn't on and I rev it up, the light will come on. It's never constant though....

I also have the miss/stumble/hesitation up to 2k rpms. It's pretty damn annoying.

From all I can find online it usually turns out to be a bad coil, but it's not setting off any trouble codes and tripping the Check Engine light.

I guess the only thing to do is go coil by coil swapping in a new one to see if it clears up.

When mine was the coil the previous 2 times. I set a trouble code. Not this time. Leads me to think in my scenario it is the alternator.

[2K2 LS1]

Duralast gold lifetime warranty?

They told me it had to test bad before they would replace it!

[scootro]

They told me it had to test bad before they would replace it!

drop that sumbitch in a bucket of water before you take it up there! lol...

[forbes]

had this on a truck once... turned out to be a bad engine to chassis ground

[2K2 LS1]

Where can I find a good pic of the grounding points on the mustangs?

[greenbullitt]

take the brushes out of the regulator, then itll test bad!

[2K2 LS1]

take the brushes out of the regulator, then itll test bad!

Badass idea

[john98gt]

there are several grounds on your car. 1. behind or infront of the negative battery post depending on how you look at it, should be a green 8mm head bolt. 2. from the driver side motor mount to the frame rail just behind the driver side sway bar mount , 3. on the driver side motor mount stud. Its the biggest of them all and actually ties into the starter harness. hope this helps. also as far as the humming goes there should be 2 gray plugs with wires going into them by the coils on number 1, 5 cylinders. they are noise suppressors