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2.5tdi. WOT hesitation and dash lights on

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by samiam, Sep 25, 2011.

  1. samiam
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    samiam New Member

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    [Sep 25, 2011]
    My allroad has recently developed a problem at full throttle. I put my foot to the floor and a moment later the (AKE) engine begins to hesitate, it smokes, then if I hold for a second or two the ABS and ESP lights come on followed shortly after by the air suspension light. If I then back off from full throttle things return to normal and the ABS and ESP lights go out followed shortly after by the air suspension light. Mid throttle it appears to run fine, fuel consumption is normal, no oil consumption. The VP44 injector pump was replaced about 18months ago.
    I live a long way away from any code reader, so no codes to report sorry.
    Any thoughts?
    #1
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  3. Rob519
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    Rob519 New Member

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    [Oct 4, 2011]
    Hi Samiam,

    Just a few thoughts.

    If you let the car warm up (go for a drive) and try to rev the engine whilst in neutral will it rev all the way through to the top end of the rev limit? If not then it could well be your Maf sensor has failed. To confirm this you can actually disconnect the Maf as the cars ECU will automatically revert back to pre-programed settings. If once you’ve disconnected it you go for a drive and everything’s fine, you know the Mafs the problem. (This may cause your engine warning light to pop on but with a bit of luck it will go out again when you plug you Maf sensor back in)

    Also does the engine seem a bit lumpy at idle? and does it smoke?

    Might be worth cleaning the EGR valve.

    Both suggestions may not make a difference but both are free and easy things to do without the need of a pc etc…

    Hope this helps
    Rob

    N.B. I drive the 1.9tdi saloon but the basic principles are the same.
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  4. skyegtb
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    skyegtb New Member

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    [Oct 5, 2011]
    Hi Samiam, my 2001 AKE Allroad 2.5TDI suffers very occasionally from the same issue. I have VAGCOM but nothing striking comes up as a fault code for me. After searching the web a number of suggestions have been made to me as to what could be causing this. Likely culprits are: faulty brake pedal switch or faulty ABS controller or faulty MAF or finally it could be due to worn camshafts on the 2.5TDI engine. Quick question, does your cruise control work? On my car the cruise is dead and it looks like this may be related to the ABS controller, which could be the cause of my occasional blip - same as you get.
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  5. adamss24
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    adamss24 Well-Known Member

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    [Oct 8, 2011]
    I have had the same issues on a few occasions on different v6 tdi AKE engined cars. All had cruise control and both had a blown brake light bulb. One of them had a fully overhauled engine (rebuild done by me) with brand new cylinder heads. Also both had refurbished VP44 injector pumps in the last 2 years as well. I would try swapping the MAF first with a known good/new unit. That will clear some of the confusions...
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  6. samiam
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    samiam New Member

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    [Oct 31, 2011]
    Ok I've had it at a service agent. It's the 550 code that keeps coming up. MAS seems ok. The prime suspect according to the mechanic is the #3 injector, it has the wire coming out of it a needle valve sensor (sorry the correct name is eluding me). Trouble is that's expensive and is only a 'might' fix. Other option lies in the brain of the VP44 pump (which was replaced 20k ago)


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