[RobDaley]

Hi guys.

Long time lurker on this and other forums and have always found what I'm looking for without having to start a thread. I am, however, now seriously stuck and in need of some wisdom.

I have a 2006 E90 330d MSport which won't charge properly. My alternator was playing up about 8wks ago, so had that replaced with an RTX one, but the car wouldn't charge even to 12v when running.

I then dropped it with an auto-electric place that had it for almost 3wks and had to bow out, as they couldn't pinpoint the problem. They replaced the RTX with a Bosch unit, both were bench tested and fine, yet the car still only hits about 11.5v when running. They checked all wiring, even disconnected all electrics and just had the engine 'stand alone', yet this still didn't improve things. The battery is decent, only 7 months old and Halfrauds have tested it and it's fine.

Has anybody got any ideas on this? Is there any reason why these alternators would not work right with my engine and it'll need the Valeo one?

Car is currently with another well respected auto electrics place who - after a week - are still at a loss.

Thanks for taking the time to read.

Rob.

P.s. if it has any bearing on responses...
A) The car is remapped (done last November).
B) Also, after picking it up from the second garage, I was in a bad mood and nailed it at one point (on my own stretch of private dual carriageway...) and as I hit 90-100mph, I noticed my C110 reader was showing the voltage at 13.5-14v. This soon dropped down to about 12v when pulling up at home a mile up the road though.

[robnitro]

If you Rev the engine and voltage goes up it could be these issues:
Alternator field brushes/regulator not giving full field current to charge at low rpm
Or the dde isn't properly demanding that it needs more field current... Voltage detection problem?
Or the wiring to the alternator is not connected well, so the alternator field current isn't being controlled well.

In ista-d/rheingold there is troubleshooting testing available to try on the alternator.

[RobDaley]

Originally Posted by robnitro

If you Rev the engine and voltage goes up it could be these issues:
Alternator field brushes/regulator not giving full field current to charge at low rpm
Or the dde isn't properly demanding that it needs more field current... Voltage detection problem?
Or the wiring to the alternator is not connected well, so the alternator field current isn't being controlled well.

In ista-d/rheingold there is troubleshooting testing available to try on the alternator.

Thanks for the response. The voltage doesn't go up when I rev it, I just noticed it that once when booting it. It hasn't done it since.

A guy on another forum has suggested trying a different battery even though the one that is on has tested ok, as apparently it ended up being the cause of another member's problems, despite ruling it out early in the same way I had.

Bench testing of this alternator showed it to be working fine. So I was kind of expecting it to be something more management related (ECU?), but will try the battery first.

[Ken Oath]

As mentioned already, diagnostic interrogation using ISTA+ can help determine any fault codes and troubleshoot.

You could try disconnecting the IBS and checking the BSD line is connected to the alternator.

[RobDaley]

Just thought I'd update this thread for anybody who experiences similar issues in the future.

Problem solved!

It was the crankshaft pulley. Apparently it was spinning on idle, with no visable wobble/buckle, but when they revved the car, it would just stop in place. This is why it was hard to spot, as it's quite low down. None of the garages I'd taken it to had seen one do that before. All sorted though. Thanks for any input.