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Both fuel trims 0... whats up!?

limbo118118 Jun 14, 2018

  1. limbo118118

    limbo118118 LORD

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    Vcds . Block 032. Both fuel trims are on 0.

    Recently had everything unplugged doing jobs... got it all back together... drove it around the estate and noticed boost gauge is now sitting at 0 at idle!? And when i rev a tad it goes up!
    Doesnt make sense...
    cars running very rich..
    sounds like external wastegate is leaking every so often at idle! Checked seal and its fine.
    - no fault codes on vagcom
    - no boost leaks
    - no vaccum leaks that i can find.
    - inspected dump valve seems fine.
    - inspectes FPR. Seem fine

    left car running with block 32 on
    ...and still sitting at 0 fuel trims 5 minutes later! Whats going on!?? Help! Cannot figure this out at all!!
     
    Last edited: Jun 14, 2018
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  3. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow... Staff Member Moderator Audi S3

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    Is the boost gauge a vacuum gauge or electric?... what does block 115 say on idle? can you validate this with A N Other boost gauge?

    zero'd trims suggests either a recent fault code reset (reset trims too and they take a little while to kick back in) or some element of its readiness state is not working (typically N249 or similar resistered out incorrectly)

    If its running rich then it could be a few things but ideally would want to log to see what everything is doing... the ECU uses the sensors to determine how to run the engine... if ones of these is running incorrectly but within the bounds of plausibility then the ECU may not throw a fault unless the poor running causes another fault condition to to execute...

    Prime candidate is the MAF... have seen these under/over read causing similar symptoms....

    Given the level of 'tune' on your car it may be worth your while booking in for an hour at bills...

    <tuffty/>
     
  4. limbo118118

    limbo118118 LORD

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    Cheers for the reply paul.

    Boost gauge is vaccum. Never been touched always worked.

    Will check block 115 tommorow!.

    I had cleared fault codes. Only one being battery.
    So maybe another little drive to see if fuel trims kick back in.

    I will double check over all connections to sensors too.

    I unplugged the maf sensor while idling and it made no difference? Except throwing fault code up. I will check what its reading on idle too for this.

    Yeh im starting to think that. Its one those issues which i carnt figure out and its only done it since i had everything off as i had gearbox off for strengthening. Pain in the ass!
     
  5. badger5

    badger5 www.badger5.co.uk Site Sponsor

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    no point. he wouldn't turn up "again"
     
  6. limbo118118

    limbo118118 LORD

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    When i spoke to you last bill i said it was a mis-communication over that booking. I am not a "time waster" never have been. I put my money where my mouth is and stand by it. If your interested in helping give me a message if not il look else where.
     
  7. badger5

    badger5 www.badger5.co.uk Site Sponsor

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    you have my number if you wish to book in. Deposit WILL be required
     
    Rainbird likes this.
  8. limbo118118

    limbo118118 LORD

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    Thanks bill sounds like il be in contact this coming week if i carnt figure it out here.

    Some photos of vcds today...

    Things that i think are weird..

    Boost pressure? Are the figures correct? This is all at idle! The right hand number slowly climbed when i unplugged MAP sensor

    It is reading maf.
    Still no fuel trims.
    Lambda voltage doesnt change with it plugged in - unplugged?...

    Boost gauge shows 0 at idle and then when revved it goes up. Into boost like 5-10psi.

    Any help :(

    20180616_170738-1209x1612.jpg 20180616_172906-1209x1612.jpg 20180616_174305-1209x1612.jpg
     
  9. badger5

    badger5 www.badger5.co.uk Site Sponsor

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    if boost gauge takes its feed from plenum it should be seeing vacuum on idle no Zero
    no switching voltage on lambda is not normal..
     
  10. limbo118118

    limbo118118 LORD

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    Found the tiniest of holes of my intake manifold yesterday. Couldnt hear it but had my hand down by the hoses double checking and then felt cold air from somewhere an found it. So fixed that

    Also got new lambda to fit today

    Fingers crossed we see some difference now

    received_10155217725357271-432x768.jpeg received_10155217732457271-432x768.jpeg
     
  11. limbo118118

    limbo118118 LORD

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    Put back together today.. new lambda fitted...

    lambda control measure block 001 values changes while engine running

    New boost gauge - fixed vac leak on manifold, and now have nice -20 vaccum at idle! Rev and goes to 0.

    Still not showing any fuel trims but not sure if these will come up after only idleing for couple minutes or need to go on a drive?
     
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  13. badger5

    badger5 www.badger5.co.uk Site Sponsor

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    you got a non return valve somewhere in your gauge? or pipe which collapses under vacuum etc?
     

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