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Thread: 2007 123d Small turbo not spooling.

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    Regular Chris D's Avatar
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    2007 123d Small turbo not spooling.

    Noticed that it was down on power in the lower rev range over the weekend, more so on our way back from Paris. Sluggish until about 3.5k rpm then woosh! off it goes.

    At the time, I put it down to having a full car load.

    Had it MOT'd today with our local indy BMW specialist. Passed ok with a few advisories (pitted discs). However, on collection he said he'd noticed that the small turbo wasn't spooling up. The lack of low range ooomph earlier in the week makes sense now!

    Said it could be one or more of a few things. Open valve (actuator?), split vacuum hose, broken flap??? Said the latter was brittle and prone to failure.

    I'll have a gander at the weekend. If I can't see / find anything obvious then I'll book it in with them next week.

    Any tips on where to look first / what to start with?
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    Regular Diamond Hell's Avatar
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    Sounds like a problem with your brittle flaps.

    No one like brittle flaps.
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  3. #3
    Regular Chris D's Avatar
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    Where are said brittle flaps
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    Regular Ian H's Avatar
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    Failed actuator, ebc or split hose would be most likely I'd have thought.
    Any fault codes showing, can you check?
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    Regular Chris D's Avatar
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    Not yet. I have a generic obd2 reader. Will it work? Not doing owt until weekend.

    Surprised BMW indy didn't run a diagnostics. It was only in for an MOT mind.

    Hoping something simple like a split hose or faulty actuator.
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  6. #6
    Regular Floyd's Avatar
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    If it was a vacuum hose on the actuator then you'd still have waste gate spring pressure. This would give you some low down boost before the large turbo takes over. That leaves the boost hose split or broken waste gate flap. You'll hear a boost hose leak if someone revs it in neutral.
    BMW 3.0 Z4 Roadster. Touareg 3.0 V6 TDI T2. Subaru Impreza Turbo 2000.

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    Regular Chris D's Avatar
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    Quote Originally Posted by Floyd View Post
    If it was a vacuum hose on the actuator then you'd still have waste gate spring pressure. This would give you some low down boost before the large turbo takes over. That leaves the boost hose split or broken waste gate flap. You'll hear a boost hose leak if someone revs it in neutral.
    Cheers ears.

    As above, if I can't find it quickly and easily then it can go to the local BMW indy up the road.
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  8. #8
    Regular Chris D's Avatar
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    Can't see owt obvious. I was on my own so could only rev and listen from the door opening. Couldn't hear anything that resembled a vacuum leak from where I was standing. It sounds a bit rough up until about 3-4k RPM though.

    It's off to the Indy next week.

    Arse.
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  9. #9
    Regular Floyd's Avatar
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    Sorry to hear that chap. If you were nearer I'd give you a hand.

    I did have a new thought that there must be a diverter 'flap' somewhere and perhaps the actuator that control that is not operating? The diverter flap must choose which turbo to point the exhaust gases at.
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    Regular Chris D's Avatar
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    Thanks mate, it's no drama.

    I'm hoping it's a simple fix that may require a cheap(ish) part and some labour costs only. I don't have the time or interest any more to take stuff apart, especially stuff like this.

    Changing discs & pads I'll still do. Really can't be arsed with stuff like this anymore.
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  11. #11
    Regular Chris D's Avatar
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    Diagnosis completed. Perished vacuum hose.

    I'm not sure which one exactly. The chap said it had been glued on by someone before and was now perished beyond re-usable.

    Tested with a hose from another car and it was completely restored to full power.

    New hose on order, to be fitted tomorrow. Bosh!
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  12. #12
    Nice simple fix. Great stuff.

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    Thatís a result mate, back to POWER
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  14. #14
    Regular Ian H's Avatar
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    That's a lot better than it could have been, nice result, simple fix
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  15. #15
    Regular Floyd's Avatar
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    Vacuum hoses are pretty cheap. Not sure why it would be glued!

    Good news and hopefully an easy fix
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  16. #16
    Regular Neil Mac's Avatar
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    Quote Originally Posted by Floyd View Post
    Vacuum hoses are pretty cheap. Not sure why it would be glued!
    Sometimes hoses are glued on during engine assembly, as the line operator can't reach the area once it's in the car to reliably attach a hose clamp in the correct orientation.
    "Fortunately, I'd taken a spare Gearbox, Turbo, Actuator, Banjo Connector, Steering Rack, Driveshafts, ECU, Wideband sensor, 57-51mm silicone reducing elbow and a Copper Banjo Washer." - Nige

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