Dark exhaust and loss of charging voltage

[Tord Andreassen]

Im hoping someone can help me out with this weird behaviour my car had today.

Its an Audi A6 2003 sedan 1,9TDi, multitronic gearbox, FWD, bought in Germany.

After turning on the ignition, the RPM fluctuated between 800 and 1200, and it seemed like it was going to stall, but it didn’t.
I noticed very dark exhaust coming out – not blueish, not white, but like the engine was running very rich.
Then the battery warninglight came on, and the voltmeter gauge pointed at 12V. I suspected something wrong with the serpentine belt, like something was stuck, so I shut the engine down and opened the hood, only to find out everything looked completely normal.

After 5 minutes I started her up again, and everything seemed normal.

Should I be worried?

Additional info: both drivebelts, belt tensioner and alternator pulley was replaced recently. Waterpump and timingbelt has also been replaced.
I suspect the Ac-compressor clutch is bad because its not engaging the compressor at all. (The pulley does spin with the belt) Could low freon levels be the cause for this? The cooling has acually been rather poor recently.

Topic

[college man]

You could be having a charging issue which will make the electronics due weird things.
Check that the charging system is in good working order. That would be the battery and alternator.

http://www.ericthecarguy.com/faq/solving-automotive-electrical-problems

http://www.ericthecarguy.com/faq/solving-automotive-performance-issues

[Tord Andreassen]

Thanks!
I will definitely take a closer look at the alternator. The battery is in good condition with 12.5V, as I would expect since its only a couple of months old.

But, just because Im curious:
-why all that black exhaust?
-Ive driven the car 3 times more today, with no problems at all. If the alternator was the problem, what are the consequences if I just continue driving, waiting for it to die completely?

[Larry Bible]

Are there any codes set? Next time this happens, put a voltmeter across the battery and see if the battery voltage is between about 13.5 and 14..5 volts while the engine is running. If so, the alternator is still working. You need to also look for freeze frame data.

With any electronic system, if a lot of weird things are happening, the problem usually relates to the power supply. In the case of your car, the battery, alternator and associated wiring is the heart of the power supply.

Hope this helps.

[Tord Andreassen]

Thanks!

No, there wasn’t any diagnostic trouble codes set.
Haven’t seen the check engine light pop on neither.

[Shaun Flichel]

Your alternator is going, hense the battery light. But do make sure all connections are tight first

[Tord Andreassen]

For anyone experiencing the same problems:

The symptoms was caused by a stuck/faulty EGR-valve, which had to be replaced.

[college man]

[quote=”carsley” post=166652]For anyone experiencing the same problems:

The symptoms was caused by a stuck/faulty EGR-valve, which had to be replaced.[/quote]

Did not see that coming.

[Tord Andreassen]

The guy at the workshop did also mention the alternator/battery when I first spoke to him.

Maybe it makes more sense if I tell you that I experienced trouble 3 times after posting here. In the first two cases I had rough idle only (fluctuating rpm). The third time the car would crank but not start at all.

[Author]

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