Voltage dropping/Electrical Probs...

[Mootzimus]

Okay, my 2000 A4 Camaro is having some electrical problems and my damn GM dealer is trying to rip me a new ****. First I was having a really bad rough idle; the car would nearly drop to 500RPM give or take and was throwing a misfire code. So I cleaned the throttle body and cleared the code and everything worked okay for about a week. Then the rough idle slowly came back until the car was getting close to stall RPMs and I threw the same misfire code again. So this time I took it to the dealer just to see what was up since I really haven't had much time to work on it. They cleared the code and said everything seemed fine and two weeks later the damn rough idle was back and my voltage gauge was randomly dropping below 11 (however the lights weren't dimming).

So this time I went back to the dealer and gave them hell. They looked at it more in-depth, I suppose, and they tell me that the reason for my voltage drop was because my alternator was going and the rough idle was because of my plugs and wires. I have been running on ngk's and msd wires for the past 3 years and had no problems. They quoted me 550 for changing the alternator and 600 for changing just the PLUGS and WIRES which is friggen crazy. Anyways, I was going to be out of town and figured have them at least change the alternator while the car was there. I shouldn't of shelled out the $$$ for them to do it but oh well, too late now. However, I wasn't going to spend 600 to just have them change my plugs and wires so those I did myself in no time. Was a b**** with my Pacesetters but just took patience.

First I tried Bosch Platinum +4 with my original MSD wires to see what would happen and it fixed the rough idle but during acceleration the car would bog and stutter so I figured what the hell and go with Accel wires and new NGK's and that fixed the rough idle thank god. However, my damn electrical system is still randomly dropping/fluctuating and my oil pressure randomly fluctuates now. But, with the gauges fluctuating I really don't feel much of anything running different w/ the engine nor do my lights dim.

For reference sake, my battery (Optima Yellow Top) is only 2 years old and gets perfect voltage while the cars off and on. I also checked all my coils and they seem fine. I've gone through my Chilton's and the forum and well I'm pretty much lost at this point. Could it just possibly be my gauge cluster or what, any ideas or info would be very much helpful at this point???

[StevenC]

Re: Voltage dropping/Electrical Probs...

Your battery doesn't matter when the car is running, the alternator powers the engine at that point. If you get a voltage drop and a pressure drop at the same time, that sounds like your motor is dropping revolutions. As the motor spins below a certain point, the alternator cranks slower and your oil pump is also going to pump slower. (As you rev the motor, your oil pressure should go up from idle - but don't free-rev).

I would check outputs from the alternator and check for fuel and spark at the cylinders. That will tell you if your alternator swap was solid and if the auxiliary systems for fuel/spark are working. Keep in mind something simple other than an alternator might be causing it not to run properly like a wire or ground.

A while back I had the same symptoms and it was right before my water pump let loose. The shaft was getting loose and would wobble and that would make the belt slip a little bit, which meant it wasn't cranking the alternator as hard. So I know what you're talking about, but check everything about the alternator and for fuel/spark. If you don't know what to look for, let us know and we'll post for you.

[Mootzimus]

Re: Voltage dropping/Electrical Probs...

Yea, I'm kind of getting new into checking this sort of stuff on my own. My father used to help me with this stuff but my parents just divorced so I'm tryin to figure this out on my own rather then handing over more money to the dealer. If you guys could kind of point me in the direction I need to be at...I would really appreciate it.

[StevenC]

Re: Voltage dropping/Electrical Probs...

Check the belt first. Check to make sure it's fresh and also tight. Check the various pulleys, idler pulleys, & belt tensioner. Items powered by the belt all have the pulley on the front, a shaft that the pulley spins, and a seal. At some point the shaft may get loose or the seal may leak and cause that unit to go out. IE like my water pump. If that happens or the belt tensioner isn't working, the belt will slip and you'll see what you're experiencing.

For just alternator issues, I'd look at the alternator & battery. But what you're telling us, by saying the voltage & the pressure both drop, makes me really think you're dropping rpms. When does this happen? Every day? On startup, on acceleration, on turning, on slow speed, below 1500 rpm, etc. Does it happen often or just a couple of times so far? I'd be wary and know something is on it's way out, but keep an eye on it to find out what. We can tell you more when you post up details.

Good call on making sure you diagnose the part first. Too many people have a bad idle and throw parts at the car and 15 parts later, still have trouble. Spend the money you'd spend doing that on either diagnostics at a shop or your own toolset and you will be able to fix any future problems on your own. Would you go to a doctor if you had chest pain who decided to take a lung out, put a stent in an artery, and do a bypass without running a scan or doing tests just because he didn't want to spend the time or money on them? Don't do it to your car.

[Mootzimus]

Re: Voltage dropping/Electrical Probs...

Thanks for the advice; I'm going to be checking all what you suggested out today. On top of a few other things as well. I was reading in one of the threads about the coil packs. That even though the primary and secondary resistances showed to be good it was the problem. So I'm going to swap those around and see what happens. Was thinking to check all vacuum lines as well.

About the voltage and pressure drop, it happens every day and every time the car is running but only when its in gear. The rpms it happens at is around 1500 and below give or take. However, It won't happen when its in park or neutral though. Also, my car only has 28k on it...I bought it in 2000 with only 34 miles on it. Its been mostly garaged kept, I don't know if that matters or not. I'll post an update later today after I did all the checks...thanks again.

[Mootzimus]

Re: Voltage dropping/Electrical Probs...

I checked the belt and all connecting to it and everything seems fine. I also checked all the wires and connectors and still seems good, no burns or loose wires, etc.

Going to be checking the coil packs and such now.

[landj]

Re: Voltage dropping/Electrical Probs...

While your under the hood, I would also check the vacuum hoses for cracks or leaks or if one has been disconnected. Rather new car for that, but you never know.

If your rpm's are dropping just when idling you may want to check the Idle Air Control (IAC) valve and electrical connectors. A repair manual will have a simple resistance test you can run with a multimeter.