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Help with a running problem on boost please

Discussion in 'A3/S3 Forum (8L Chassis)' started by S£, Jan 27, 2011.

  1. S£
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    S£ Member

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    [Jan 27, 2011]
    I come across a problem with my S3 yesterday, when driving gently it's seems fine but when I put my foot down a bit and the boost comes in strong (around 2500-3000) I get what feels like a misfire, just like when a coil pack goes. Happens in any gear, basically when the boost peaks.

    I've dowe a scan and it's not showing any faults, also a missfire log and no cylinders are missing, also done the maf test thing recommended for checking for boost leaks, at 3000rpm I'm getting 8g/s am I right I thinking it's got a small boost leak? as I should be getting 9-10g/s

    Would this cause my miss/juddering problem? Anyone else had a similar problem?

    Hope someone can help, cheers
    #1
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  3. Prawn
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    Prawn My other car is a MINI!!!!

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    [Jan 27, 2011]
    This happened to me on my old AGU. Does is still misfire when cold? Interestingly, mine would run fine for a few minutes when cold, then start missing once warm when boost went above 10psi.

    I changed the plugs for brand new denso IK22's, and this didn't help at all. I spent months trying to solve the problem and replaced almost every other ignition part, only to find in the end it was the plug gap too wide!

    New platinum NGK plugs in there gapped correctly, and it's been perfect ever since.
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  4. S£
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    S£ Member

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    [Jan 27, 2011]
    Cheers prawn, it does it from cold to hot.. But surely if it was a miss it would show up when I take it for a run plugged in?? The plugs are old though, I've had it nearly 3years/25,000 miles and not changed them yet, got a service in 1000 so was going to do them then..
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  5. s3dave
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    s3dave TFSI Hybrid Supporter

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    [Jan 27, 2011]
    Lol 25k....I think it would welcome some plugs....
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  6. S£
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    S£ Member

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    [Jan 27, 2011]
    Lol... that's what I was thinking 10k ago but the garage was like, nah they're fine they'll last till next service!

    I might start there tomorrow then, best plugs and gap for a mapped S3 anyone??(AMK)
    Last edited: Jan 27, 2011
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  7. Prawn
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    Prawn My other car is a MINI!!!!

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    [Jan 27, 2011]
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  8. s3dave
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    s3dave TFSI Hybrid Supporter

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    [Jan 27, 2011]
    0.7mm gap for a mapped s3/a3, im going for NGK IRIDIUM IX BKR7EIX next slightly cooler plug
    Last edited: Jan 27, 2011
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  9. s3dave
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    s3dave TFSI Hybrid Supporter

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    [Jan 27, 2011]
    Got these in at the mo ^^^^, to be fair no problems, although there well burnt on the porcelain
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  10. S£
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    S£ Member

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    [Jan 28, 2011]
    Managed to get two fault codes this morning



    1.3 Special Notes
    16684/P0300/000768 - Random/Multiple Cylinder Misfire Detected

    Possible Causes
    Air Intake System leaking
    Fuel Supply faulty
    Injector(s) faulty
    Ignition Cable(s) and/or Spark Plug(s) faulty
    Ignition Coil(s) faulty
    Exhaust Gas Recirculation (EGR) Valve (N18) stuck/open
    Camshaft Position Sensor (G40) faulty
    Possible Solutions
    Check Misfire Recognition
    Check Air Intake System
    Check Fuel Supply
    Check Injector(s) and Injector Sealing
    Check Ignition Cable(s) and Spark Plug(s)
    Check Ignition Coil(s)
    Check Exhaust Gas Recirculation (EGR) Valve (N18)
    Check Camshaft Position Sensor (G40)
    Special Notes
    This DTC indicates that one or multiple cylinders are misfiring, but the ECU fails to identify the cylinder.

    And


    16686/P0302/000770 - Cylinder 2 Misfire Detected

    Possible Causes
    Ignition system
    Fuel injectors
    Fuel pressure
    Running out of fuel
    EVAP canister purge valve
    Evaporative emission system
    Low compression
    Base engine problems
    Controle Module damaged
    Special Notes
    This feature search for engine misfire in a specific cylinder. Most of the time the cause for a misfire is a lack of combustion in a cylinder due to absence of spark, poor fuel metering, or poor compression.


    Is the anything I can rule out or look close at because the car does run fine until heavy boost?
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  11. s3dave
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    s3dave TFSI Hybrid Supporter

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    [Jan 28, 2011]
    coil packs...
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  12. Welly
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    Welly VX220 SC Driver :)

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    [Jan 28, 2011]
    Yep, looks like the coil in cylinder 2. Although I would change the plugs first personally.
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  13. S£
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    S£ Member

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    [Jan 28, 2011]
    Yeah cheers guys, just changed the plugs and swapped the packs over for the drive home, now missing on cylinder 1.

    I'll get a coil pack Monday, it did look shot as soon as I took it out, surpisingly the plugs weren't that bad.
    #12

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