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1.8t avant warm start problems help!

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Mark L, Jun 18, 2008.

  1. Mark L

    Mark L New Member

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    I have a 2003 A4 runs fine when going and starts fine when cold yet when its warm takes 10-20 secs to fire and sometimes wont fire at all. Any ides???
     
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  3. evilscotsman

    evilscotsman Space Cowboy

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    I would start by looking at the engine temp senders, theres 2 I think like other vag motors. One for the temp gauge and one for the ecu. It might think its cold when its hot and applying too rich fuel at start up like the old style engines with choke on, an old engine would never start hot with the choke out.

    The other thing to consider is fuel running back or getting air bubbles in the engine lines when sitting hot. Try putting the ignition on for about 3 seconds and off 3 times each time before trying to start it when its hot, to prime the fuel rail well and see if it starts easy. If it does then check the fuel system, if not change the temp sensor, but its likely the temp sensor any way :)

    btw if anyone's interested they can get a hand held OBD scanner (like vag com, in that it gives full english descriptions of all fault codes found in the car and clears the fault codes too) for £40, with free shipping and no laptop required. Theres a lot of cool stuff vag com does that a hand scanner can't but if you want to know whats wrong with the car anytime its acting up then you could do worse to have one in the toolbox or boot.

    http://easydirectshopping.com/advan...s=obd&osCsid=14c32dbf5662eb96bb8791a23a11ea5d

    Check it out and see what you reckon, im gonna have one myself at the end of the month. I know the owners of the site, but it really is a bloody useful gadget and I hope the mods don't mind me plugging it to you! Its a helluva saving from even a basic dealer diagnostic and you can do it as often as you like.....it works on all european & british cars from 96 not just VAG.
     
  4. Mark L

    Mark L New Member

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    OK ive changed the temp sender but still have the same problem, also tried turning the key three times and it doesnt make any difference, i can hear the pump working when i turn the key so i dont think it is the fuel supply, i have worked out though that when the engine is hot (90deg) it fires no problem its just when its warm aourn 45deg. Any ideas welcome!!
     
  5. evilscotsman

    evilscotsman Space Cowboy

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    hmmm its a weird one. I think you need to get it scanned for fault codes somehow so you know where to start looking.

    The engine has to have either a poor / no fuel supply or ignition spark in order to refuse to start but the ecu could be doing it due to a sensor too, interestingly when it was a hot day, my car would refuse to start 3 times in a row.....i found that I had been lowering the windows off the remote on hot days and that was killing the fob battery so the immob didnt recognise the key and wouldnt start until the battery recovered a bit after a minute or so!

    Its the fact that it starts at 90 deg that makes it weird eh?

    Any strange noises when its started / running any of the cold, warm or hot starts? Or any other symptoms or events recently?
     
  6. Mark L

    Mark L New Member

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    Ther are no other symptoms but when it struggle's to start and eventully fires the ect light is on and stays on, could it be anything to do with the coils? The cars done 120,000 and has three of the existing coils still fitted, ive replaced one as when i bought it had the wrong coil fitted but this didnt clear the fault.
     
  7. evilscotsman

    evilscotsman Space Cowboy

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    to be honest its a tough one. To work cold or hot but not warm, will be awkward to track down.

    As the problem is temp related I first blamed the senders, tho you didnt say if you replaced both or just one of them? One is for the gauge and one is for the ecu cold enrichment program.

    coils are certainly to be considered but at what, £35 each theyre a bit dear to buy as a trier eh.


    Screwy ecu???
     
  8. Mark L

    Mark L New Member

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    I only changed the one temp sensor, located at the top of the block by the bulkhead, i have looked and cant find the second sensor, does anyone know were its located?
     
  9. evilscotsman

    evilscotsman Space Cowboy

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    On a hose?
    [​IMG]
    did it look like this?
    [​IMG]


     
  10. Mark L

    Mark L New Member

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    OK still got the same problem but today the car wouldnt start at all, i can hear a strange noise from the fuel pump almost as if it has seized, as the car turns over the pump is intertmittent and making a whining noise.
     
  11. evilscotsman

    evilscotsman Space Cowboy

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    oops, maybe a call to vagparts for a pump and filter....or try removing it and cleaning the filter if its like most submersible pumps it clogs if its run low on fuel a lot or if theres any rust particles in the fuel.
     
  12. Mark L

    Mark L New Member

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    OK i got home from work last night, tried it again and it fired up first turn of the key and no noise from the pump WTF!!! I borrowed a mates scanner and it has come up with the following codes,16706 - Ignition/Distributor Engine speed input circuit - No signal.17772 - Not listed in the manual, does anyone know what this is?Help is much appreciated.
     
  13. Mark L

    Mark L New Member

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    After searching various forums i have come to the conclusion that its the engine speed sensor or the cam positioning sensor.Anyone know which one also best place to buy???
     
  14. evilscotsman

    evilscotsman Space Cowboy

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    try vagparts?
     
  15. istoo

    istoo Member

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    cam position went on my 1.8T but it was would start OK just went into limp mode constantly. and would cap the revs at about 4000rpm.
     
  16. seany26

    seany26 Member

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    Hello, first sorry for resurrecting this old thread, but the problem described is exactly what I'm getting. Did any of you lads get to the bottom of the problem. It's a pita and is really annoying and embarrassing.
     

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