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Thread: 2006 Vauxhall Signum Mass airflow sensor problem...

  1. #1
    Join Date
    Apr 2012
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    Default 2006 Vauxhall Signum Mass airflow sensor problem...

    Hi,
    I have a 2006 Vauxhall Signum 2.8 V6 Turbo... which also has a LPG system fitted.
    It keeps having a power drop and the service light flashes on with the traction control light. They stay on and then eventually the service light cuts out and the engine management light comes on. (I Believe this might be called safe mode?)

    Eventually both lights go out and the performance picks up again.

    It has a lumpy tick over when this happens and also cuts out after immediately starting up.

    The diagnostic code says it is a mass air flow sensor. I have replaced this and it was fine for a few miles... but then the problem happens again.

    What else could it be? Some one said that the sensors need cleaning or throttle sensor needs cleaning?

    Laurence

  2. #2
    Join Date
    May 2008
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    8,269

    Default

    Presumably you got P0100 - mass air flow sensor - as the fault code? Was this on the pedal test or on Tech 2/3? The problem with this code on Vauxhalls is that if the engine stalls, as when it cuts out after starting, the slight back pressure in the manifold confuses the MAF and up comes this code.
    Have you tried driving it with the MAF disconnected? If the power comes back then you know it is faulty. Does it run the same on LPG and petrol? If so then a proper diagnostic check may help.
    If the LPG is a genuine factory fitted system then diagnostic equipment can read it and maybe find the problem. If it is an aftermarket system then you will need more specialised help.

  3. #3
    Join Date
    Oct 2011
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    Default

    the lpg needs servicing every two years i think as the valves gowl up and causes problems.

  4. #4
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    Apr 2012
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    I just had the LPG serviced - its all fine.
    I tried unplugging the airflow sensor and driving it - it is still low on power and running lumpy.

    Does this mean it is not the Airflow sensor? Could it be the throttle position sensor? Does it all need a clean up?

    Is the throttle position sensor an expensive job?

    It runs fine for miles then the service spanner light and traction control light comes on causing the power to drop and the tick over to go lumpy.
    Then eventually the service light turns off and the engine management light flicks on.

    After a few more miles both lights turn off and the power comes on a bit more. But this cycle repeats over and over.

    I am worried that the engine may be damaged even more if I continue to run it like this.

    The problem happens with LPG on and off.

  5. #5
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    May 2008
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    In which case you need a proper diagnostic check to find the problem. One of those tuning firms with a rolling road may be better than a dealer as they will work with cars like yours a lot. Or maybe a Vauxhall specialist, again likely to be cheaper than a dealer.

  6. #6
    Join Date
    Apr 2012
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    Default so... does water/rain/spray cause warning lights to come on??? Tried everything else.

    OK so I took it to the garage and LPG guys. They have replaced the LAMBDA sensor, spark plugs, brand new bosch mass air flow sensor, new nozzles for the LPG system and gave the whole system a check over. They ran it 30 miles with no problem. NO lights on.

    I then had it home - took it for a drive around the block and booted it and still no problem or lights on.

    Then I took it to be cleaned by the local car hand wash people with jet washes. When I came to turn the car on, the same problem occurred. The lights (both service and traction control) came on and it went in safe mode.

    After a few starts and stops the service light flicks off and just leaves engine management light on with traction control light on too. Eventually the traction light goes off just leaving the engine management light. On petrol it seems to be missing and a slight lumpy tick over.


    Is water/spray or washing it causing something to short out? Whatever it is it causes a fault code for the mass air flow sensor... however I have just had a brand new bosch one put on.

    The garage does not know what is wrong... so I am at my wits end. Any advice?

  7. #7
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    May 2008
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    The traction control seems to be the problem here from what you are saying after the washing. It would be handy if you could get the car on a diagnostic and had the ABS and Traction system checked for fault codes. Something as simple as an ABS sensor or other component linked to it may be shorting and bringing on the ABS which in turn puts the engine management light on. Or undo each sensor and spray with WD40 to get rid of water. The ABS unit may also be getting wet, worth a quick look.

  8. #8
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    Apr 2012
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    Would this also cause the engine to go in to safe mode? Would it cause the service light (the one with the car and spanner) also to come on?

  9. #9
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    Apr 2012
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    Also would this make the engine seem to miss slightly on tick over?

  10. #10
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    You need to remember that all the control units in your car are linked together in a system called Can bus. In very simple terms it is like a ring main in house electrics. So, if you have a fault in the ABS for example, this fault will be transferred to the body control module (central computer), to the instrument panel ECU, to the engine ECU, to the airbag ecu etc etc. Lets say the ABS sensor on the front that is also the vehicle speed sensor (usually front left) is faulty. This sensor sends a signal to the ABS and Traction control ECU. This in turn is then sent to the engine ECU so the correct fuelling is applied. The signal is also sent to the instrument ECU so the speed shows on the dash. The airbag is also involved as there are lateral and longitudinal sensors which tell the Traction how fast you are accelerating and cornering. So, its not just a case of look at codes for the engine. You should do a complete check of all the ECUs in case there is a common error.

    The miss on tickover needs to be looked at in a logical way. 1. spark plug check. 2. coil check using diagnostic tool in actuator mode. 3. air leak at the manifold or other induction pipes and vacuum ones too. 4. compression check. 5 valve timing check.

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