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Thread: constant full boost!!! boost leak? MAP sensor?

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  1. Angry constant full boost!!! boost leak? MAP sensor? 
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    used VAG-COM the other day to log the specified boost against the actual boost. there is a major difference in values as you can see. (see attached images)



    I jacked up the car and got under it while running. I set vag com to cycle through the N75 test cycle. when i looked at the actuator it was not moving at all. i pulled off the vacuum line and the actuator rod shot back. the vacuum line was sucking really hard. so this makes me believe that my car is constantly fully boosting. Is this normal? would could cause this to happen.

    also when the car is idling, the specified boost is at 1336mb, where as the actual is aprrox 1000 all the time. it does bob around abit when reving up.
    the symptoms from driving are,
    1. excessive fuel consumtion. i get 35mpg max
    2. lack of low end power.
    3. hard to start when cold.
    4. smell of unburnt diesel alll the time.

    this is a weird, and im totally baffled to what is causing it.
    the car has had:

    new turbo
    engine coolant sensor
    fuel temp sensor
    MAF sensor
    cambelt changed
    egr and intake cleaned


    please help!!
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  2. Re: constant full boost!!! boost leak? MAP sensor? 
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    Do you mean the vacuum line from the intake manifold was sucking at idle with no throttle applied?
     
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  3. Re: constant full boost!!! boost leak? MAP sensor? 
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    No, i mean exactly what i say, the vacuum line to the turbo actuator is constantly sucking at idle. it wont let me do the N75 tests because of this. when u pull the hose off the turbo actuator, the rod shoots straight back and the turbo stops boosting.

    with all this cold weather, the car starts on 3 cylinders and its burning oil for a few mins then stops. these look like signs of worn injectors seals. going to do a compression test soon. does anybody know what sort of compression ratios i should be getting?

    I want to make sure that its the injector seals before buying them because they are £16+VAT each at VW!

    please pick ur brains and help!

    shawn
     
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  4. Re: constant full boost!!! boost leak? MAP sensor? 
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    To me this problem sounds like a faulty map sensor. I have the same symptoms but I am using the diode mod which means i have the map sensor disconnected.
     
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  5. Re: constant full boost!!! boost leak? MAP sensor? 
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    In Basic Seings 011 the actuator is opened and closed by the ECU operating the N75 valve so the actuator should cycle off and on every ten seconds or so and you can see the actuator respond to this by full scale defelection each way.
    Anthropogenic climate change, the biggest con inflicted on mankind since religion...

    Slava Ukraini
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  6. Re: constant full boost!!! boost leak? MAP sensor? 
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    Quote Originally Posted by boratdi150 View Post
    No, i mean exactly what i say, the vacuum line to the turbo actuator is constantly sucking at idle. it wont let me do the N75 tests because of this. when u pull the hose off the turbo actuator, the rod shoots straight back and the turbo stops boosting. with all this cold weather, the car starts on 3 cylinders and its burning oil for a few mins then stops. these look like signs of worn injectors seals. going to do a compression test soon. does anybody know what sort of compression ratios i should be getting? I want to make sure that its the injector seals before buying them because they are £16+VAT each at VW! please pick ur brains and help! shawn
    I think I would be getting a vac Gage on the actuator and make sure its set to open at correct pressure(as new turbos are not always set up correctly from new,sometimes even from the dealers !)--start to open at around 2--fully open by between 16--18--ya can get exact numbers from google !!
     
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