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I need some help understanding my VCDS ignition timing figures.

Discussion in 'A3/S3 Forum (8L Chassis)' started by Westy, Dec 18, 2009.

  1. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Jan 4, 2010]
    From that last log image, it looks as though IAT's aren't playing any part in your timing pull...

    The log you did using block 031 doesn't show the excessive timing pull you are getting in the block 118 one you did. Maybe worth doing a few more runs using blocks 031, 115 and 020 and only post results of bad timing pull to see if the fuelling is an issue. Based on the originally posted image, fuelling looks fine and the timing pull is within normal params etc... on the logs where you are puling 5's there is no fuelling block so can't tell if the requested is fine but the actual is lean which would pull timing...

    Out of interest, is the vacuum hose to the FPR ok? The original one is prone to disintegrating, check this at the inlet mani too, its in a really awkward place (just for fun) but if you have a leak here that will affect fuel mixture higher up the rev range.

    <tuffty/>
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  2. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Jan 4, 2010]
    gotcha.. ta

    AIT's yep.. cold day.. starts 8'C ends 20'C, some 12'C rise 22 seconds later
    cold day, intercoolers working ok, presuming a 4th/5th gear pull given its 22second of full throttle

    looks fine to me on Cf pull, BUT its cold outside and I would expect to see these higher when its hot and summer (wishfull thinking on my part)

    I would do a run logging 001, 031, 118 - (llambda correction, request vs actual lambda, ait's and actual boost)
    ideally looking at 020 as well to see.. but only 3 blocks at a time possible on vagcom

    {edit} - just quickly lookin g back at one of your logs, its running pretty lean fella.. more than I would like to see myself. I would want to be seeing 0.8x under boost not the 0.9's you are getting. check that fpr hose like tyffty says.. your regulator might not be rising rate.. but that said, the map request does'nt ask for more fuel either..
    Last edited: Jan 4, 2010
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  3. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jan 4, 2010]
    Cheers guys :icon_thumright:

    I'll do a bit more logging when I can and post up the results. Can one of you just clarify that the FPR hose is the one that runs into the top of the DV (N249 bypass has been done)?
    Last edited: Jan 4, 2010
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  4. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Jan 4, 2010]
    FPR (fuel pressure regulator) is at the end of the fuel rail. FPR pipe comes out of that to the bottom of the inlet mani. The OEM one is kinda fabric covered...

    <tuffty/>
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  5. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jan 4, 2010]
    Thanks again matey. I'll hunt around for a photo of where it is. Do forge and the like do a replacement hose?
    #45
  6. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Jan 4, 2010]
    Just a length of silicon vacuum pipe will do. Unsure of the exact size off hand...

    <tuffty/>
    #46
  7. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Jan 4, 2010]
    its just a 3mm hose from memory - silicon hose.. and would as std run direct from manifold just above alternator to the fuel pressure regulator on the end of the fuel rail (rhs)
    #47
  8. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jan 4, 2010]
    If anyone can post a pic of the hose in question for me it would be very appreciated. I'll make replacing this hose a priority just incase it is damaged.
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  9. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Jan 4, 2010]
    dude... engine cover off
    fuel rail. (on top of fuel injectors) on inlet manifold adjacent to cyl head.
    on right hand side of the fuel rail is a round thing with a single vacuum pipe going to it.
    fuel pressure regulator
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  10. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jan 17, 2010]
    Right I've finally got so e free time to do this but I could only pick up 4mm vac hose. Can anyone confirm if 4mm will be ok to replace the frp or has it got to be 3mm to keep the pressure right?
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  11. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Jan 17, 2010]
    so long as it seals it will have no effect on pressure. fpr is a small outlet tho so 4mm will likely be baggy and not seal properly
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  12. S3 CYP
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    S3 CYP Member

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    [Jan 17, 2010]
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  13. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jan 17, 2010]
    Cheers guys. I'll order some 3mm. Just got one end of the frp off and the pipe is very brittle and damaged. I'll try the 4 mm now and change it when I get the 3 mm. Hopefully the clamps I have will be tight enough.
    #53
  14. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jan 17, 2010]
    Ok it's on and I've got the clamps tight. If anything it's no worse than it was before. I'm going to fill up with some decent fuel and I'll do another run later.
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  15. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jan 17, 2010]
    Ok just done another run. Put 99 ron fuel in this time too. Outside temp was 6 degrees celcius and as you can see from the following screenshot the AITs are not really causing a problem.

    Bill does this still look lean? I thought the lambda readings looked slightly improved at the top end of the rev range? Thanks.

    [​IMG][​IMG][​IMG]
    #55
  16. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Jan 18, 2010]
    3300rpm to 4900rpm is still in the 0.9x fueling which is a bit lean to me.. from 4900rpm up its ok afr wise
    I like to see 0.8x lambda once boost has spooled personally.
    #56
  17. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Jan 18, 2010]
    I'm hoping that the 99ron fuel and the new hose for the FRP are the reason the fueling isn't so lean at the top end. Is there anything else I can check that might also help with the fueling? Any other hoses or the injectors?

    Thanks again for your help Bill.
    #57
  18. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Jan 18, 2010]
    ensure your FPR is doign what its supposed to, pipes on it correctly etc
    logging block 001, 031,118 next time will show what sort of adjustment if any the ecu's having to make to achieve the requested afr

    its the map which is asking for it to be what its doing now.. the request and actual follow so I doubt anything else you can do will change owt
    #58

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