Jerking when setting off

Discussion in 'Fiat' started by Vennwood, Aug 20, 2015.

  1. Vennwood

    Vennwood Read Only Funster

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    When we pull away from lights or junction the camper jerks quite badly until we get going. It feels like the accelerator return spring (if there is one) is missing. Also when idling the engine RPM starts to creep up from 750 to 1500. All the local Fiat dealers are fully booked next week and we leave for France at the end of next week. The engine is the Fiat 3.0 ltr and its a 2009 model any suggestions would be very helpful
     
  2. Mel

    Mel Funster

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    Manual or cofortmatic?
     
  3. irnbru

    irnbru Funster Life Member

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    Our AT does that too when engine is cold
     
  4. Vennwood

    Vennwood Read Only Funster

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    Manual
     
  5. Techno

    Techno Funster Life Member

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    I've never experienced that with my 3 litre and the rpm is 800 at tick over whether hot or cold
     
  6. Vennwood

    Vennwood Read Only Funster

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    It was fine until a couple of days ago and while we haven't owned it long it has been fine. Full service history. Just a B***er this is happening just before we set off.
     
  7. Techno

    Techno Funster Life Member

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    And you haven't got a check engine warning?
    IMHO it sounds as though the throttle valve is not closing fully.
     
  8. Judge Mental

    Judge Mental Funster Deceased RIP

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    do you really need a Fiat garage to diagnosis this..look around locally for recommended commercial garage..
     
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  9. Techno

    Techno Funster Life Member

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    Peugeot or Citroen garage will do the same job. EDIT or even IVECO seeing as it is their engine
     
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  10. Vennwood

    Vennwood Read Only Funster

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    Thanks Andy I'll check around - never thought of that
     
  11. Judge Mental

    Judge Mental Funster Deceased RIP

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    I just googled and there are loads including Iveco which would be my first call if Fiat/Peugeot/ Citroen busy. would try and find someone good outside the expensive franchised set ups..loads of reputable mechanics around.
     
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  12. John Laidler

    John Laidler Funster

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    The jerking might be engine mounts and the tickover issue unrelated. Not sure that help!
     
  13. dave newell lvs

    dave newell lvs Trader-Vehicle Services

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    Not sure about the jerking on take off but the idle speed issue could be down to a faulty alternator.

    D.
     
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  14. Chris

    Chris Funster Life Member

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    I seriously misread the title to this thread.

    I thought "setting" read " getting"

    :D
     
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  15. Mousy

    Mousy Funster Life Member

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    Great minds think alike! I almost choked on my mouthful of spaghetti Bol.
    Opened the thread in great excitement only to find technical questions like manual or auto:eek::rofl:
     
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  16. Vennwood

    Vennwood Read Only Funster

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    I thought that only a Fiat dealer would have the "magic box" that would connect and instantly tell you what the problem was.

    To go back to something Andy mentioned. I did have an amber engine warning light on when I picked up the camper but the dealer said it was "due to the engine battery going flat while it stood on the forecourt and that had been reset" To be fair I haven't had the problem since.
     
  17. Vennwood

    Vennwood Read Only Funster

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    Thanks Dave,

    I'll bear that in mind if I can get it booked in and mention it. What would cause that? - The camper has a B2B fitted and looking through the previous owners service history this vehicle has a history of "flat engine battery" The selling dealer had to "clear the fault log as there were 7 instances of low engine battery" Again looking through the records it has had 2 replacement engine batteries in the past 5 years - odd don't you think?
     
  18. Judge Mental

    Judge Mental Funster Deceased RIP

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    Yes...points to wot Dave said:)

    Any auto electrician could varify.....
     
  19. Vennwood

    Vennwood Read Only Funster

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    You would think so but the records show it has been into several Fiat dealers and Hymer dealers with this problem but none have identified the problem as a faulty alternator. I'm thinking that Dave may have hit on something the others have missed.
     
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  20. dave newell lvs

    dave newell lvs Trader-Vehicle Services

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    It is feasible that the B2B is causing the revs rising issue. The alternator output is regulated via the engine ECU, if it sees a lower than expected voltage at the alternator output it will increase rpm to compensate. The B2B works by fooling the alternator to produce more current, it does this by artificially putting more load on the alternator. If the engine battery is lowish, say 50% charged, then the additional load of the B2B may just cause the voltage at the alternator output to be lower than the ECU wants to see so it raises the rpm. Try removing the B2B fuse from the engine battery to rule it out.

    D.
     
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