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6 Series DIY
6 Series Do It Yourself (DIY) forum.

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Old 04-10-2013, 10:28 AM
tom jones tom jones is offline
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Location: fort Lauderdale
Join Date: Aug 2012
Posts: 15
Mein Auto: 645
2005 645 ci acting up big time

I'm got an ongoing problem I hope someone can help me with. 88k miles well maintained but started idling really bad about a year ago. Idle pulsates up and down when I come to a stop.
Idle will drop to almost a stall then shoot up to 600-700 rpms. It's like the car realizes it's about to stall at idle and wakes up. Other times it idles perfectly. I've had it to two dealers who said no faults come up on the computer and they just put in some injector cleaner (which actually helps until that tank of fuel is gone). What the hell? My engine malfunction light comes on when the pulsating happens. I'm wondering if all this is related to a low voltage issue (weak battery and alternator not putting out enough voltage to activate the fuel injectors well at idle?). I get a light when I fire her up in the morning that says "Charging Malfunction"and a battery icon on the dash. Maybe these are all related?
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Old 04-14-2013, 02:42 PM
sick645ci sick645ci is offline
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Location: UK
Join Date: Mar 2013
Posts: 26
Mein Auto: 645Ci
Originally Posted by tom jones View Post
My engine malfunction light comes on when the pulsating happens.
Surely then the dealer can read the fault code? Unless the car is throwing some random unrelated codes, hence the dealer saying no codes.

1. Definitley sort out the battery/alternator issues. Maybe as the engine comes down to idle, the voltage drops too much causing the issues. Modern day car computers are very voltage sensitive.

2. What sort of petrol are you/have you been using?
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Old 04-16-2013, 12:30 PM
soldier-ina-6er soldier-ina-6er is offline
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Location: Tacoma, Washington
Join Date: Feb 2013
Posts: 67
Mein Auto: 2005 645CI, sport package
most likely a cpv valve issue. At around 100k miles the rubber in them will start to get brittle and fail to creat the proper vacuum. The fix is easy and cheap (40 bucks and there's a DIY on this site, very simple)

I'd suggest replacing them regardless. Even if you still have issues after that you're going to need to replace them eventually.

Other checks would require having the code read. I heavily encourage you to go to an indy to do this as the stealership will tell you your car is about to explode and needs $12,000 in repair work immediatly :/.

Good luck my man.

Last edited by soldier-ina-6er; 04-16-2013 at 12:31 PM. Reason: cpv valve, not pcv valve
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Old 04-17-2013, 05:55 AM
janbrasna janbrasna is offline
Exhibition of speed FTW!
Location: PRG-NYC-SFO
Join Date: Nov 2012
Posts: 19
Mein Auto: 645Ci / 130i / Z4 2.5i
It could be the CCV or a few other well known problems, but the battery drain sounds weird. Get a new battery and recode/register it well, but it won't prolly fix the idle acting up.

Some info for the CCV:


Also check these N62 rough idle related treads:

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Old 05-07-2013, 07:28 AM
FSUTOM FSUTOM is offline
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Location: Heathrow FL
Join Date: May 2013
Posts: 4
Mein Auto: 645 ci


Last edited by FSUTOM; 05-09-2013 at 07:47 AM. Reason: may affect warranty coverage
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Old 05-12-2013, 03:46 PM
Trompa401 Trompa401 is offline
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Location: providence,ri
Join Date: Apr 2013
Posts: 11
Mein Auto: 2005 bmw 645ci
2005 645 ci acting up big time

Mine did this and i replaced 2 coil packs and an injector drives like new

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