Fabio, you're right, it's not unusual for a "good" alternator to act as you describe. Sometimes they stop exciting at lower RPMs, especially when new - there is little residual magnetism on a new alt. Also, very old alternators may act this way for a variety of reasons.

Again, many thinks for the tips and insights.

I drove the car today for an extended period of time, and it seemed to get better! It now swings up to full charge with just a blip of the throttle . . . maybe 900 rpm. A couple of times when started, it came up to full charge by itself. It seems to keep charging while at idle, although the gauge is jumping around, but now staying over 12 volts.

I think I will hook up a voltmeter somewhere so I can monitor it accurately while I'm driving, and see exactly what is going on. Beats taking the pod out again until I'm sure something needs fixing!

Chris,
In addition to the afore mentioned.
Check your body/chassis grounds, some look good but are ...crunchy. And green pad the battery ground
area behind the tool kit.
Could be a gremlin, or a bad new alt. if it keeps bothering you, yank it and have it tested at a auto batt. elec. shop.

Mine also acts like it doesn't excite right away. My charge light never comes on when I turn the key before I start up the car and my volts read low when I start up until I blip the throttle, then all is fine. When I shut the car down, the light comes on as everything is shutting down.

I also have a Bosch alternator with the exciter resistor installed.

If the light never comes on your exciter circuit doesn't work - an open circuit connection somewhere.

Alan

Just a quick update . . .

I've driven the car every day this week, and it seems to get better everyday. On a cold start-up, when the idle is a touch higher, it now starts charging right away. Occasionally, when I start the car warm, the charge light is on until I blip the throttle. A slight blip works; I no longer have to rev it to 1,500 rpm for it to work.

Thanks, Alan.

I'll have to pull the pod this winter and check things out. Any other places I should be looking besides in the pod?

The connections at the alternator and the CE panel & 14 pin connector near the jump post.

Alan

Thanks to Alan and SharkSkin there's some extensive troubleshooting tips on that exciter circuit here.

For those interested, here's a photo of the bad printed circuit board . . .

Attachment 313658

Holy crap... Any idea what caused it to delaminate like that?

Just a quick update. I've been driving the car every day, including stop and go traffic,and it appears to be charging fine.

Where did you find the replacement circuit flex board for the instrument cluster?

Thanks,

http://www.mailordercentral.com/928i...asp?number=928 641 939 00

Here you go . . .

Fixed link:
http://www.mailordercentral.com/928i...928 641 939 00