Ahsai

'02 996. Alternator does not start charging until ~4 seconds after the engine fired up. Warm or cold, SAI pump running or not. Makes no difference.
Once it starts charging, it stays at good level 13.5~14.1v whenever the engine is running. Drive belt is not slipping. No warning lights or CEL. No codes from Durametric.

I noticed this behavior on the voltmeter in the dash and also verified the same from the cigarette lighter.

I know that some Bosch alternators have a soft-start feature where charging will be delayed up to 14s (to reduce alternator load impact immediately after start up) but AFAIK, our stock alternators don't have such fancy feature. I wonder if the regulator was replaced with one having such feature. Other than that I can't explain it. Anyone experienced this?

Schnell Gelb

Maybe it has this CR719 inside?
http://www.bosch-semiconductors.de/m...140307_v10.pdf
or

Ahsai

Yup, that's what I'm thinking but I'm too lazy to remove the alternator to find out.

Very disconcerting when I see the voltmeter reading staying at 12v for 4s when the engine is running. Kinda like seeing the oil pressure at 0 bar when the engine is running

Schnell Gelb

You'll have a great opportunity to check next time you have to chase a vacuum leak at the bottom of the vacuum accumulator :-) .

Ahsai

Not a chance! I replaced that with a new one when rebuilding the engine.
I also did a leak test (like you) before installing the engine too

wildbilly32

I would be much happier with 12v for four secs. rather than 0 bar running...always!

Ahsai

True true

Btw, this behavior was captured clearly in my first start video.

gnat

check/change the battery. If it's not holding a good charge or has damaged cells that could be the issue. If the act of starting is drawing it down too low the alternator will be busting its *** to bring the charge back up on the battery. While the battery is sucking up all the power, the voltage will drop and normalize at 12v (the battery).

wildbilly32

First start video...Oh the one where you couldn't get the engine to stay running?

Yeah went back and watched the gauge...interesting. If it is consistent your guess may be right...soft start. I'm not familiar with that but it does make sense.

Ahsai

Good thoughts but of course I've also tested my battery and it seems healthy. I can do one check though. I can connect my booster pac and start the car and see if that makes a difference.

Ahsai

Lol...should have also got my left hand and key into the frame so ppl could see me cycling the key. The camera lens was not wide enough.

Yeah I'll just have to wait till next time I remove the alternator. Then I can check the regulator.

Ahsai

Ok, tested with booster pac and no difference. My battery is 700 CCA and my battery tester measured the same (a brand new battery usually measures 10% higher).

That was a good thought though.

wildbilly32

BTW how is the break-in and impressions of engine going? Any updates?

Ahsai

​​​​​​Engine is pulling strong and it's very smooth. No leaks, no warning lights, no codes, and no issues other than this delayed charging. Fuel trims at 2~4%

Switched to DT40 at around 500 miles and it's at about 700 miles now. Plan to drop the oil pan at 2,500 miles, do some inspection and send the oil out for UOA.

DD'ing it now...hard to keep my foot off the gas pedal with the new found torque

Imo000

The exciter circuit in the alternator might be going or the reference wire, in or outside of the alternator, is loose/broken. Pull the alternator, have it bench tested and then go from there.