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Misfire in Passat

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  • 21-07-2016 9:20pm
    #1
    squiddy
    Registered Users Posts: 33 ✭


    The car is a 2008 Passat 2.0 TDI CR. While overtaking in 4th a Big Bang came from under the bonnet and the car has no power and although it can reach 80kmh it will chug and misfire a lot of the way. When I put my foot down there is nothing. Is this the turbo??


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    #2
    George Dalton
    Registered Users Posts: 5,728 ✭✭✭George Dalton


    Sounds more like a boost hose has come off.


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    #3
    squiddy
    Registered Users Posts: 33 ✭squiddy


    George Dalton wrote: »
    Sounds more like a boost hose has come off.

    Is that a big job?


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    #4
    George Dalton
    Registered Users Posts: 5,728 ✭✭✭George Dalton


    Not usually.


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    #5
    Renegade Mechanic
    Registered Users Posts: 7,934 ✭✭✭Renegade Mechanic


    squiddy wrote: »
    The car is a 2008 Passat 2.0 TDI CR. While overtaking in 4th a Big Bang came from under the bonnet and the car has no power and although it can reach 80kmh it will chug and misfire a lot of the way. When I put my foot down there is nothing. Is this the turbo??

    Is it very noisy now? Very loud hissing with lots of black smoke behind? If so, George is correct and it shouldn't be a big fix, unless a pipe has burst, in which case you'll just have a higher price on the work needed in replacing said pipe.


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    #6
    squiddy
    Registered Users Posts: 33 ✭squiddy


    Renegade Mechanic wrote: »
    Is it very noisy now? Very loud hissing with lots of black smoke behind? If so, George is correct and it shouldn't be a big fix, unless a pipe has burst, in which case you'll just have a higher price on the work needed in replacing said pipe.

    There's no smoke seemingly it's an air intake valve or something like that a light for that is on the dash


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    #7
    Renegade Mechanic
    Registered Users Posts: 7,934 ✭✭✭Renegade Mechanic


    squiddy wrote: »
    There's no smoke seemingly it's an air intake valve or something like that a light for that is on the dash

    I know the one. At list I think.. The valve they're likely referring to is actually a shut-off valve that slams shut when you turn off the ignition, to facilitate a quick, refined engine shut-down. Good few diesels have them now.
    runawayengine.jpg
    They're known - but not notorious, at least - to not open/move properly after a good while, which would definitely affect things like acceleration.

    Also very handy at stopping runaways, though not infallible, for the reasons above :o


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    #8
    squiddy
    Registered Users Posts: 33 ✭squiddy


    Renegade Mechanic wrote: »
    I know the one. At list I think.. The valve they're likely referring to is actually a shut-off valve that slams shut when you turn off the ignition, to facilitate a quick, refined engine shut-down. Good few diesels have them now.

    They're known - but not notorious, at least - to not open/move properly after a good while, which would definitely affect things like acceleration.

    Also very handy at stopping runaways, though not infallible, for the reasons above :o

    Probably a silly question but would it effect fuel economy also?


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    #9
    Renegade Mechanic
    Registered Users Posts: 7,934 ✭✭✭Renegade Mechanic


    squiddy wrote: »
    Probably a silly question but would it effect fuel economy also?

    If it's not opening fully or sticking half way, the restriction to airflow would reduce power,meaning you need to press the accelerator more, so I'd imagine it would to some degree.

    There isn't generally a "bang" when they go though, to the best of my knowledge, unless the bang was more the engine simply juddering against the mount when the intake went closed for whatever reason.


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