The voltmeter on my car doesn't seem to be acting like it should. When I first start the car on a cool morning it will read about 15v...good so far. I'll cruise down the road and by the time the car is warmed up it will be right around 14 where it should be. But once I get into traffic it will fall around 13v and possibly lower if I'm there for a little while. This seems to happen much faster on hot days and the voltage usually won't stay @ 14v even while cruising when it is hot out. Also when I'm idling (about 550 rpm in gear) the meter will bounce a little bit. The connections are all clean at the battery and the alternator. Any thoughts? Thanks

 

You might wanna stop into auto zone and see if your alternator and your battery are functioning properly.

 

Sounds about normal. In Texas it gets pretty hot here and the hotter it is, the more strain you put on the electrical system. Also, do you have an underdrive pulley?

 

mines always around 12-13 but im running a crazy sound setup.

 

No, I have the original. Whats strange is sometimes it will act fine even in warm weather and other times it won't. Like this morning in traffic it hung right around 13v and the needle wasn't bobbing either. But on the way back up in near zero traffic it did. One thing I did notice is that the car seems to idle a little rough sometimes and the needle will bounce when it idles like this.

 

Sounds like occassionally your engine will idle too low and the alternator output will drop because of the low idle. It's best to comfirm the voltage at the battery with a multimeter. Any loads like AC or an AMP will only serve to exagerate the problem.

If a low idle is the case, best to check the EGR first and then the IAC and throttle body. BTW a modified exhaust can effect the function of the EGR.

One other thing to check that many overlook is the ground strap from the engine to the frame.

If you get the multimeter try one other thing. Put the meter on "AC" only for this test. Put one lead on the negative battery terminal and the other on the output post of the alternator. Be sure the reading is 0.03 VAC or lower. If it is higher, you may have a diode problem in the alternator.