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S3 Spluttering and holding back under boost.

Discussion in 'A3/S3 Forum (8L Chassis)' started by Barks, Apr 25, 2011.

  1. Barks
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    Barks Member

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    [Apr 25, 2011]
    Hello,

    I haven't been using my car for a few weeks as it has been nice weather and I have been force to ride my bike to work so my car has just been used to potter down the shops.

    Since last taking the car for a good drive I have changed the Fuel filter (ebay purchase and cut the old one open and it was filthy), fitted oil catch take and simplifed the PCV system and finally made a heat shield for the cone filter.

    Anyhow I went to take the car for a 'drive' on thursday and it is running like **** under boost, it feels like it is pulling back and spluttering.

    So i decide to do some logging on vagcom and on channel 020 and the ECU is pulling 8 and 9s on the ignition advance at around 4500rpm under heavy accelleration in 4th gear. MAF flow seems good to this point but I backed out at anything above 4500rpm to save any damage to the engine.

    If I accelerate in a gradual manner the car is smooth and revs to 6000rpm with no problems.

    The MAF has been replaced and the problem is still there. All the hoses have been checked and they all seem fine.

    I dont know if I have a fueling problem, if there is a problem with the ebay fuel filter and this is causing lean fueling hence the high ignition advance CFs. (is this the symtom are the cause??)

    Any ideas or thing to try would be greatly be received.

    Thanks
    #1
  2. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User

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    [Apr 26, 2011]
    Have you had the coil packs changed?
    #2
  3. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Apr 26, 2011]
    It does sound like a coil pack. When you logged the timing pull was 1 injector working harder than the other 3?
    #3
  4. Barks
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    Barks Member

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    [Apr 26, 2011]
    No, I haven't but they are the Hitachi Bolt down type and all 4 cylinders are failing
    #4
  5. Barks
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    Barks Member

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    [Apr 26, 2011]
    I know what you mean but all 4 cylinders were pulling, sure they can't all fail in one go.

    Wouldn't a failing coil pack just cause a misfire and the engine to run rich if anything???
    #5
  6. Y83OLK
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    Y83OLK Hulk Smash!

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    [Apr 26, 2011]
    Have you changed fuel supplier recently?.
    Mine has similar symptoms currently... Im blaming morrisons 95 fuel.
    #6
  7. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Apr 26, 2011]
    I've had a failing coil pack cause poor starting when cold and I chased every other sodding component trying to work out what it was.

    Coil packs also show their weakness when working under load.

    Unfortunately the only way to rule out coil packs is to swap them with know good ones. Have you got any audi buddies near by? ;)
    #7
  8. Barks
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    Barks Member

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    [Apr 26, 2011]
    Affraid not, it had crossed my mind that it could be a crappy fuel issue, I use Shell Vpower from the same station

    but I am sure it would have to be 20% water to run like it does.

    I have around 1/4 of fuel left, so I want to run it a bit lower then put a full tank of Vpower in.

    I have got a fuel pressure gauge lash up to try when I get home form work tonight to try to prove the fuel filter
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  9. Welly
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    Welly VX220 SC Driver :)

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    [Apr 26, 2011]
    Why are you filling an S3 up with that *****??

    Naughty Naughty!! lol
    #9
  10. Barks
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    Barks Member

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    [Apr 26, 2011]
    I agree I do need a sub in a set of coil packs to prove one way or another, my friend has a passat, hopefully they will be the same fittment

    Thanks
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  11. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Apr 26, 2011]
    oh yes they can. just less often.
    Bristol S3 owner has identical thing.. bough 4 "new" coil packs... and it misfired horribly under boost.. Fitted known to work other ones and it magically fixed itself. I believe they were beru ones fitted.

    any oil in your charge pipes? pop em off and have a look, wipe off any residue and run it again, then recheck.. High CF's can also be from excessive oil/breathing, as well as lean running.
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  12. Welly
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    Welly VX220 SC Driver :)

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    [Apr 26, 2011]
    OK, so I would approach this sort of problem in the same I would approach a problem at work.

    It was working. It's not now. What's changed?

    Obvious things - is fuel filter the right way round? What make was the filter you fitted? Could be something fuel filter related as under heavy fuel demand you are seeing the problem, as well as the high timing pull indicating a potentially lean condition.

    Other things - PCV simplification - all the hoses tight, no leaks?
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  13. Barks
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    Barks Member

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    [Apr 26, 2011]
    I try and get hold of some coil packs and sub them in, the prove one way or another, could be and expensive one!

    I will pull of the card pipes and have a gander

    Thanks info
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  14. Barks
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    Barks Member

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    [Apr 26, 2011]
    I am going to check the fuel filter tonight, the crimped end of the can is pointing to the front of the car, which was the same as the one that was fitted. I can't remember the manufacurer but was a ebay purchase and certainly not genuine.

    I have checked for leaks around the PCV and also vented the engine into the free air and bunged the TIP. I will have another look though

    Thanks for the info
    #14
  15. Barks
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    Barks Member

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    [Apr 26, 2011]
    Hello some more help needed,

    I have T in a pressure gauge to the pipe on the injector side fuel rail:-

    [​IMG]
    [​IMG]


    I have a 3 Bar fuel pressure regulator fitted,

    on idle the gauge displays around 2.5 Bar and on light load this goes up the 3 bar as seen on the video:-

    [video]http://www.youtube.com/user/Davebarks?feature=mhum#p/a/u/0/L2J849a66fM[/video]

    I haven't got a video on this (As it would be a bit dangeous to film) but when under load the fuel pressure goes of the scale >4 Bar.

    Surely the FPR should hold this at 3 bar under all conditions??
    #15
  16. Barks
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    Barks Member

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    [Apr 27, 2011]
    Any ideas, faulty FPR??
    #16
  17. Welly
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    Welly VX220 SC Driver :)

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    [Apr 27, 2011]
    1.8T FPRs are based on 3 BAR plus boost pressure. It's a rising rate regulator.

    You would only have to be running 14.5 PSI boost to take it off the scale on your gauge.
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  18. Welly
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    Welly VX220 SC Driver :)

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    [Apr 27, 2011]
    It will have it written on the ends normally, one end will say in and one will say out. I would certainly check that out, however this photo suggests it is correct:

    [​IMG]
    #18
  19. Welly
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    Welly VX220 SC Driver :)

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    [Apr 27, 2011]
    Coils and plugs are the next stop mate.
    #19
  20. Barks
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    Barks Member

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    [Apr 27, 2011]
    Ah I see that would make sense
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  21. Barks
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    Barks Member

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    [Apr 27, 2011]
    I will double check the fittment tonight

    I have some new plugs on order and I should have a set coil packs to substitute in.

    Thanks
    #21
  22. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Apr 27, 2011]
    Nope.
    Its 3bar with no vac/pressure..
    2.5bar on idle vac is normal.. then its 3bar PLUS boost pressure. Its a rising rate regulator
    #22
  23. Barks
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    Barks Member

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    [Apr 27, 2011]
    Its not that then!
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  24. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Apr 27, 2011]
    wideband afr gauge sir?
    #24
  25. Barks
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    Barks Member

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    [Apr 27, 2011]
    That what will be required! Hopefully when I see you tomorrow you might be able to point me in the right direction. Thanks

    Going to change the coil packs and spark plugs tonight just to be sure
    #25
  26. Barks
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    Barks Member

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    [Apr 27, 2011]
    Right Pulled the plugs and they look like this:-

    [​IMG]

    They look like it has been running a bit on the rich side. I have some new NGK PRF6Q plugs to go in.
    #26
  27. S3KO4
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    S3KO4 Member

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    [Apr 27, 2011]
    by the looks of those plugs if anything you are running rich, plus possible over filled with oil check the dipstick on a flat surface.
    #27
  28. Barks
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    Barks Member

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    [Apr 28, 2011]
    It sure does, I have checked the oil and it it half way up the dip stick, thanks
    #28
  29. s3dave
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    s3dave TFSI Hybrid Supporter

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    [Apr 28, 2011]
    Is it just me or them plugs looks as if it is infact running lean...very white core...
    #29
  30. Barks
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    Barks Member

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    [May 13, 2011]
    Just to let people know:-

    Popped up to Bills a couple of weeks ago, it was run on the rollers, and it was advised the Coil Pack were suspect.

    Some new coil packs were fitted, and the problem disappeared!! So for all you that recommended the coilpacks... give yourselves a pat on the back, you were right!!

    Thanks

    Popped up to Bills last night for him to have a look at the excessive ignition correction factor, and once again he had a play and got rid of the worrying ignition correction factor by reducing the Boost and igintion advance,

    Ended up with 285 peak BHP on the rollers!!! Excellent for a Stage2 K04 and 3" TIP!!

    The car drives very welll and alot more progressive... Thanks Bill
    #30

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