So I finally got some decent weather again, and decided to pull out the multimeter and look at some stuff on my impala.

I followed the procedures that Danthurs put up on the how to section, and tested ignition coil posts and the battery posts to test the charging system. I took a brief look, because I didn't want to do anything that could cause any problems since I don't want to get caught with having to fix something before the school week begins again (yes I'm sorta obsessively cautious, and I was unsupervised so I didn't want to pull too much apart).

Heres what I got
The coil for 4 and 1 had a resistance of 5.85 ohms and 6 and 3 had a resistance of 5.83. I would've tested the 5 and 2 but I was a bit worried about the state of the wires as well I have no di electric grease at the moment to touch them back up (will have to do that tomorrow). They look to be in bad shape. the ends are breaking apart and on top the they are looking worn, I was afraid that if I gave the wrong one too much force while pulling, id break one, so I left the two in the middle alone.

I did some testing with the battery posts as well. Heres what I got.

Car off: 12.6 volts
Car on, at idle: A wide variety of voltages, 14.7, 5.0, 8.0, 18.3, 3.7
The voltage was constantly changing, and it happened along with the contant shudder of the engine. If you guys don't understand what I'm saying, I'll gladly put up a vid if you guys prefer. Otherwise, you guys have any ideas?

dont get it. you put a meter on the battery and its going all over like that? either you have a lead thats not contacting properly or the cables on the battery or grounds aren't attached properly.

and if your boots are bad on that end and breaking down, there likely the same on the other end and its time to replace them.

Hmm, the voltage all over like that has me thinking a alternator problem, the 18.3 is really high, could be a bad voltage regulator. When the voltage drops, the spark gets weak and the engine will stumble.

Thats exactly whats happening, I think. Theres a lot of stumbling. The voltage is jumping up and down, and as that is happening you can hear/see the engine jolt in the bay.

So what part should I be looking at?

Pull the alternator out and have it tested.

Autozone offers that for free, dont they?

I believe they do.

I went to autozone this morning and they got their tester out, crimped the clips on the battery posts and checked the car while idle. The voltages did the same thing as Saturday and went all over the place. It started out at a low voltage (I forgot the number, maybe 9? I should've brought a notebook) and then it, did the random range of voltage then went to zero. On the rest of the drive up to school, the car jolted for about a mile. Any ideas?

what would have been better would be if you took the alt to the store and have them check it on there bench setup, them you can isolate the car from the equation