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Newbie needs help, A4 1.8t no boost

Mark Revie May 30, 2018

  1. Mark Revie

    Mark Revie New Member

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    Hi, have just purchased a A4 1.8t 190 (Revo stage 1 map installed) engine code BEX, it has a boost gauge fitted but it's very flat and only goes upto 5-6psi have checked all the usual suspects using this forum but to no avail, I've tried disconnecting the maf still the same, n75 is working and fuel trims are equal, it's not logged any fault code's and doesn't appear to have any vacuum leaks so really stumped :-( any help or advice it greatly appreciated.
    I have vcds but haven't a clue how to use properly lol so if there's anyone in the teesside area who knows a bit about these then any help would be great.
    Thanks Mark
     
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  3. Leo Komninos

    Leo Komninos Member

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    On my SAAB it turned out to be a clogged cat, due to overfueling. Try disconnecting down pipe and see if that fixes issue.
     
  4. Mark Revie

    Mark Revie New Member

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    Thanks, but surely if it was blocked I would get some sort of fault code from the oxygen sensors ? And would it not affect how it runs?
    Cheers Mark
     
  5. Leo Komninos

    Leo Komninos Member

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    Never got a engine check light, but SAAB had lambda between turbo and cat. symptoms: Runs fine low rpm, but when should be in boost seems like it's asthmatic, could mistake for MAF/MAP fault. Worth a try even for shits-n-thrills ( become the road warrior and enter the Bronze!!)
     
  6. A4snake

    A4snake New Member

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    im in a similar situation as you except mines not mapped, stuck with 5psi.
     
  7. Mark Revie

    Mark Revie New Member

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    Got it sorted, now boosts to 21 psi, was all down to the cat being partly blocked so £85 from eBay for a new one and it runs great.
    Thanks for everyone's help and advice
    Mark
     
    DrStrange likes this.
  8. A4snake

    A4snake New Member

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    Did yours idle ok and generally run ok, just that boost won't get past 5/6 psi boost? im wondering if mines down to the cat, ive had slight concerns it coukd be but the bolts are rusty and seized so not fancied breaking them just to check lol
     
  9. Mark Revie

    Mark Revie New Member

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    Yeah, everything was fine just no boost, just undo the three bolts from the turbo to the cat (you only need a couple of mm gap) will be a bit noisy but should be able to tell if you give it a quick run around the block lol
     
  10. A4snake

    A4snake New Member

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    Cheers mate, mines sorted now, turns out mine was the turbo itself at fault.
     
  11. DrStrange

    DrStrange Well-Known Member

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    Good shout LEO above! (claps hands)
     

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