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Thread: BMW N52 (N52B30) Intermittent loss of power at low revs

  1. #1
    Join Date
    Nov 2011
    Location
    Ireland
    Posts
    7
    My Cars
    1999 E46

    BMW N52 (N52B30) Intermittent loss of power at low revs

    Hi All

    I'm having an intermittent problem with my BMW 2006 E63 630i (not sold in the US or Canada but many other BMW models have the N52B30 engine) since I bought it in February which is really taking the enjoyment out of the car for me. I've read many different posts on this but there seems to be no single magic bullet. Before I embark on a journey into the BMW parts black hole I just wanted to see if anyone had any good tips.

    The problem: When I try to accelerate from a slow speed (revs 1-1.5k), such as coming on to a roundabout or out of a junction, the engine power dies momentarily. It happens for a second or two and then it surges back to life. Generally happens when I least need it to - the car just seems to know when I'm trying to get into that gap!

    It can also happen when accelerating after a speed bump or when accelerating out of a slow hill. The road my house is on is quite steep and when I turn onto the road it almost always happens. In this situation I can sometimes hold it in this state by keeping the throttle steady. The revs drop below 1K and the car will crawl along and almost be at the point of stalling, then it will rasp, and finally surge forward. Letting off the throttle and then gently applying it again also fixes it.

    Some other points:
    • No fault codes
    • Doesn't seem to happen in sport mode as the revs are pushed out of the zone band where it happens. That said, I do from times sense a brief flutter.
    • Only seems to happen when the car reaches operating temperature. When I drive the 5 mile trip to work in the morning it drives like a dream.
    • This is not a slow gear change issue. The engine power dies like it is being starved of fuel

    Recent work (result of a failed water pump) includes head gasket, timing chain, water pump and thermostat, CCV and associated hoses, various oil gaskets replaced
    Auto gearbox oil sump and oil replaced
    Adaptions reset

    My initial thoughts are that it is VVT related. I have found some oil in the eccentric shaft sensor. I cleaned it up well and seems to be slowly coming back. The seal appears dry so I can only assume that it is wicking up through the sensor itself. I'm just not sure if this is the cause problem because 1) Its intermittent, 2) Only happens when engine is warm 3) Idle is fine, 4) Rest of the rev band is faultless. If the sensor was bad would the problem not be more constant? (Sorry I didn't change this anyway while the head gasket was being done but the garage didn't seem to think this was necessary).

    I'm also thinking of changing the VVT motor as it's also possible that that is faulty (why no error codes though??).

    After that there's Vanos solenoids (already swapped these around), return valves, MAF, Throttle body, and on and on and on….

    Any help greatly appreciated!!

  2. #2
    Join Date
    Nov 2011
    Location
    Ireland
    Posts
    7
    My Cars
    1999 E46
    Hi Moderators, I should have posted this in the General BMW Mechanical Help section. Can you please move it? Thnks.

  3. #3
    Join Date
    Jul 2017
    Location
    uk
    Posts
    1
    My Cars
    2006 630i sport

    bmw 630i cutting out

    hi i have a BMW 630i sport which is cutting out showing vanos fault both valves have been changed but still problem any ideas

  4. #4
    Join Date
    Nov 2011
    Location
    Ireland
    Posts
    7
    My Cars
    1999 E46
    What are the exact fault codes? Have you tried cleaning the vanos solenoids and swapping them over? If there is a problem with a solenoid this can help pinpoint it...

    I still haven't resolved my issue but plant to reply the solenoids next...

  5. #5
    Join Date
    Feb 2013
    Location
    Berm
    Posts
    1
    My Cars
    1998 BMW M3 Coupe
    Good day. Solved the problem?

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