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LIMP MODE!

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Marc1, Jan 25, 2009.

  1. Marc1
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    Marc1 Member

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    [Jan 25, 2009]
    I must be jinxed at the moment!

    Fitted HID's and LED side lights last night after a bit of a faff with an uncompliant headlamp plug. Took the car for a drive to check out the difference and the problems started.

    Filled up and restarted car - got brake warning light. Switched off and on and it was gone - put this down to the HID's or LED sidelights.

    Once warmed up and after about a 30 minute spirited drive, I change to 6th gear at 4,000rpm, revs drop to 3,000 and both rev and needles stay were they are, despite accelerator increase. :banghead:

    I had an exhaust and remap 20 days ago and haven't driven it a massive amount since. But had noticed that when changing gear at higher revs 3,500 - 4,500 the car seemed to hesitate briefly once the revs had dropped (kind of like when ESP comes on and cuts some power). I thought this could just be me, or that the turbo was having to respool, but I'd not noticed this before the map.

    Wondered what you guys thought as at the moment it could be anything, the HID is probably a red herring surely?

    I thought possibly:-
    MAF
    Boost leak
    Exhaust issue

    Any ideas would be greatly appreciated. :icon_thumright:
    #1
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  3. Marc1
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    Marc1 Member

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    [Jan 25, 2009]
    Forgot to mention that the exhaust (cat back) is from a 1.8T - so petrol exhaust on a diesel car.
    Could it be a lambda sensor clogged? I don't know where the sensor is, if it's in the cat, then it won't be that. Does anyone know how many lambda sensors is there and where are they?
    #2
  4. Marc1
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    Marc1 Member

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    [Jan 25, 2009]
    Could disconnecting the battery for 10 minutes to reset the ECU help, or am I likely to lose the new map?
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  5. evilscotsman
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    evilscotsman Space Cowboy

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    [Jan 25, 2009]
    the map wont be lost mate, its written into the ecu's rom chips, so thats ok to do. Try it, but it could indeed be the maf, try disconnecting it and see if the problem goes away? If so, then it could be bad but if no change or worse, then its not that. Could be a sticking wastegate too....slow to close the flap inside, that will drop power and cause a dead spot.
    #4
  6. Emmo
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    Emmo Member

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    [Jan 26, 2009]
    After checking the MAF, check turbo hoses incase one has come loose, which can happen after getting increased boost after a remap.

    Also the hoses on the diverter valve, check for looseness or splits.
    #5
  7. Marc1
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    Marc1 Member

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    [Jan 26, 2009]
    Thanks guys. I went to tackle the MAF, and noticed the airbox had popped out a bit at the back, so figured that must be in - popped it back and all was well - Feel a bit of a tit though now :sorry:
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  8. evilscotsman
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    evilscotsman Space Cowboy

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    [Jan 26, 2009]
    good stuff! modern cars can throw a fit over things that wouldnt bother an older design, happens to us all mate ;)
    #7

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