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Thread: GT TDI lack of power

  1. #1
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    Exclamation GT TDI lack of power

    Hi all im having a lack of power fault with my 2005 Golf GT 2.0 TDI, its as though the turbo has been taken away and feels like a flat diesel engine. The engine starts and runs fine with no misfire etc.

    I had faults of open / short circuit for the throttle motor and an underboost / low boost fault for the turbo. I found a blown fuse for the throttle motor so replaced that. As for the lack of power low boost fault i have checked and done the following,
    Checked all hoses for leaks etc. when driving no sounds of leaks either,
    checked the vac pipes to the turbo all ok,

    checked vacuum pipe working and is moving the actuator fully which I can move my self also,
    I have removed the vac pipe to turbo and ran it and still no boost,
    checked both sides of turbine and not failed,
    ran with no pipe on the exhaust side of turbo and no boost,
    ran with maf disconnected and still no boost.

    Before I remove the turbo and strip it is there anything else it could be?
    It has had a new EGR valve in the last 6 months so cant be that.
    Can the throttle motor cause this fault if it isn't opening correctly when requested by the throttle pedal?

    Any help would be greatly appreciated cheers Dan

  2. #2
    Administrator Crasher's Avatar
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    Diesels do not have a throttle, the V157 inlet manifold flap is there to act as an anti shudder shut down flap and part of the EGR system strategy. Are you getting any fault codes now?
    "I disapprove of what you say, but I will defend to the death your right to say it"

    Evelyn Beatrice Hall (28 September 1868 13 April 1956)

  3. #3
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    Hi i have no engine warning now as i cleared the codes and have driven it no more than 15 miles. if i scan it now the only fault in it is (cylinder 3 glow plug circuit Q12 electrical fault P0673).
    The boost fault was (boost pressure regulation control range not reached p02990).

  4. #4
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    Under boost is usually a vacuum control system leak, which diagnostic system do you have?
    "I disapprove of what you say, but I will defend to the death your right to say it"

    Evelyn Beatrice Hall (28 September 1868 13 April 1956)

  5. #5
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    Im using snapons solus.
    I thought by disconnecting the vac pipe to turbo would give it full boost or does the car limit power if there is a fault in the vac system? Cpuld the vac solenoid block be at fault? Or would i see a code for this?

  6. #6
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    Tother way around, the turbo defaults to off boost with no vacuum as a safety feature.
    "I disapprove of what you say, but I will defend to the death your right to say it"

    Evelyn Beatrice Hall (28 September 1868 13 April 1956)

  7. #7
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    Update and i have found the problem. I have removed the turbo and found all the bolts snapped that hold the retaining ring to hold the exhaust side to the inlet side. Ao was losing pressure from there. Can you recommend anywhere for a turbo or if anyone has one.
    Cheers

  8. #8
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    Midland Turbo in Nottingham would do a perfect job of rebuilding it for you, they are my default choice.
    "I disapprove of what you say, but I will defend to the death your right to say it"

    Evelyn Beatrice Hall (28 September 1868 13 April 1956)

  9. #9
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    Just an update of the car. I replaced the turbo and is now boosting and pulling as it should. However on full throttle there is an intermittent judder / hesitation. The fuse for the throttle intake keeps blowing so I'm thinking that the intake motor requires replacing as this is causing the judder with it sticking

  10. #10
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    Yes, blowing fuse 8 is a common problem caused by the V157 flap, it also knocks out your cooling fans.
    "I disapprove of what you say, but I will defend to the death your right to say it"

    Evelyn Beatrice Hall (28 September 1868 13 April 1956)

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