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Possible over fuelling?

Discussion in 'A3/S3/Sportback (8P Chassis)' started by Sock, Jul 14, 2011.

  1. Sock
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    Sock Shark in a Goldfishes clothing

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    [Jul 14, 2011]
    Hi all,

    Just after some advice about the S3 engines.

    I was bored the other day so decided to check the plugs and poke about a bit and I noticed they were covered in 'soot', propper caked in it if im honest but the majority of it wiped straight off.

    Also noticed that the exhaust pipes were covered and washed a load of it out the exhaust.

    Left it for a couple of days and looked again and they were black again, doesn't this mean its over fuelling?

    I have spoken to Superchips who have said they haven't had any problems with there maps causing this but did agree it sounds like its over fuelling, and it is now in at Audi who have checked and reported back that its not over fuelling ( surprise ) but when I asked if they had checked the plugs and they replied 'yes' I then asked can you explain why they are black they replied "good question, we'll get back to you on that tomorrow"!!!

    I don't have access to Vagcom etc so just after some general opinions or if this is normal?
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  2. paddy
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    paddy Audi=No fault code, no idea

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    [Jul 14, 2011]
    Plugs will tend to reflect the last use so if you started it up from cold left it running for a few minutes and then switched off they may well appear sooty. Only real way to do a plug chop is to give it a thrash and then pull the plugs straight away.when i say straight away i mean it, dont then drive home through the town and look at the plugs after that, defeats the object.lol. If the soot wipes off and the plug is reasonable underneath then i would say that is a better pointer than a random look. they should be a light straw colour ideally with no build up of deposits.
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  3. Sock
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    Sock Shark in a Goldfishes clothing

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    [Jul 14, 2011]
    Cheers Paddy I will try that, although when I took them out yesterday I had just driven up to my brothers at a steady pace to be fair and took them out within 10 mins of being there give or take as I was in a rush lol, the plugs are totally black but when cleaned off they look in good condition over all, might just change them just in case.

    I have been told that it could be a leaking injector causing the ECU to adjust the fuel to compensate thus causing the over fueling, does that make any sense?
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  4. paddy
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    paddy Audi=No fault code, no idea

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    [Jul 14, 2011]
    Yea could be mate. but if that was the case i would expect the plugs to be really coked up with hard deposits, if the soot just wipes off then it dosnt sound like its been rich for more than a few miles but without seeing them i cant really say.

    One other point is that a clogged air filter will make an engine run rich as well ??
    Last edited: Jul 14, 2011
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  5. Sock
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    Sock Shark in a Goldfishes clothing

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    [Jul 14, 2011]
    Thanks for your input mate,

    Will feed back after I have spoken with Audi tomorrow ( I'm not holding my breath for an answer lol )
    #5
  6. Ben H
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    Ben H On a journey...

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    [Jul 14, 2011]
    I've had soot coating the tailpipes ony both my S3 and old 2.0T quattro - but both with and without Bluefin maps. Sounds usual(ish) to me.
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  7. Sock
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    Sock Shark in a Goldfishes clothing

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    [Jul 14, 2011]
    Cheers Ben, don't suppose you noticed any heavy build up on the plugs?
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  8. Lewis583
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    Lewis583 Active Member VCDS Map User

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    [Jul 14, 2011]
    The tailpipes on my 20T are filthy aswell, i just think its a characteristic of the direct injection FSI system. I recall seeing a B7 RS4 on a forecourt that had sooty tailpipes too.

    In regards to the injectors, if an injector was leaking the ECU would sense this(richness) and attempt to correct by pulling fueling, so for all the plugs to be sooty all the injectors would have to be leaking which is pretty unlikely.
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  9. Sock
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    Sock Shark in a Goldfishes clothing

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    [Jul 14, 2011]
    Cheers Lewis,

    The guy that spoke to me said that the mixture would be weaker due to the leak on an injector so the ECU would increase fueling to compensate?

    I'm only a learner to this stuff so appreciate all help and I'm only passing on what I was told, plus Audi said that if the car was over fueling the ECU would thow it up as a fault?
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  10. Sock
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    Sock Shark in a Goldfishes clothing

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    [Jul 14, 2011]
    Should I upgrade the spark plugs anyway as I am now running Blufin? have seen some people have changed there's on mapped cars?
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  11. Lewis583
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    Lewis583 Active Member VCDS Map User

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    [Jul 14, 2011]
    Nah if the injector were leaking, it would be letting too much fuel into the cylinder so the ECU would reduce fueling to stay within emissions regs.

    I would think standard plugs will be fine for just a stage 1 map.
    Last edited: Jul 14, 2011
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  12. Sock
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    Sock Shark in a Goldfishes clothing

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    [Jul 14, 2011]
    Yeah that makes sense.

    Maybe I'm just not driving it hard enough to blow the soot off? lol
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  13. Sock
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    Sock Shark in a Goldfishes clothing

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    [Jul 15, 2011]
    Audi could not find any fault with the car and say the emissions test is spot on and they even consulted Audi UK for advice but could not get an answer from them so looks like i will just have to monitor it for now, car is running ok so at least thats not an issue.

    On a side note they did say the spark plugs looked like the original ones so being as it has nearly 40k on the clock I am going to change them.

    Audi wanted just shy of £14 each for the plugs! so is there anywhere cheaper and can someone supply the part number etc?
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  14. Cheese
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    Cheese Member

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    [Jul 17, 2011]
    My exhaust get pretty dirty pretty quick too.
    #14
  15. akash_sky1
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    akash_sky1 Active Member

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    [Jul 17, 2011]
    i think its pretty common with TFSIs especially one's running aggressive maps, mine smokes a bit too on WOT, think my plugs are due changing.
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  16. Sock
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    Sock Shark in a Goldfishes clothing

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    [Jul 17, 2011]
    I changed the plugs and tick over has improved and feels smoother to me, will keep an eye on the plugs
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