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  1. A4 1.8t very low boost 
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    Hi, have just purchased a A4 1.8t 190 (remapped to 225) 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.
    Was wondering if there's anyone in the teesside area with vag com who could possibly help, 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. Mark
    Kind Regards
    Mark.
     
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  2. Re: A4 1.8t very low boost 
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    Moved to the correct section.

    I would say turbo related.

    Ian
    A4 B6 Avant Nogaro Blue
     
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  3. Re: A4 1.8t very low boost 
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    Thanks rowdy, looking through the history it has had the turbo cartridge rebuilt, checking with a hand held scanner everything seems fine, fuel trims are both at 0% and runs great just no power from the turbo, the blades are turning fine with no play. Unplugged maf and still no different also checked n75 valve and again it's working fine.
    The only other thing is I have a rattle from the cat but don't know if that has anything to do with it?
     
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  4. Re: A4 1.8t very low boost 
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    Best to eliminate sensors before you head for a turbo out, try the map sensor with a friend's. If you can access vcds take a log of fuel, boost and maf at full throttle this will tell you most of what you need to know to find the problem. Can you access the map file? Has it been tuned? With petrols there may also be a lambda problem holding fuel back but it should feel more problematic than low power.
     
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  5. Re: A4 1.8t very low boost 
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    The cat could be blocked but are you sure the N75 is working and passing/stopping air flow during output tests.
    Anthropogenic climate change, the biggest con inflicted on mankind since religion...

    Slava Ukraini
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  6. Re: A4 1.8t very low boost 
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    Thanks Jim, I have full vcds but no idea how to use it for testing lol don't think it's the map sensor as it runs perfect just no boost and no fault code's.
    Yes it has a Revo stage 1 tune it's just the low boost that's the problem?
    Mark
     
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  7. Re: A4 1.8t very low boost 
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    Crasher, I have inspected the cat and can't see any blockage?
    Cheers mark
     
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  8. Re: A4 1.8t very low boost 
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    You're not going to "see" a blockage unless you take the cat off, I think the cat has broken and is partially blocking the exhaust.The turbo can't make boost with a partially blocked exhaust. Other thought is it's the wastegate on the turbo that is loose, again you're going to have to take the cat off to investigate.
     
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  9. Re: A4 1.8t very low boost 
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    Thanks calum, I will take the cat off and see what I can find? As I say it rattles quite badly lol.
    Cheers mark
     
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  10. Re: A4 1.8t very low boost 
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    How would I know if it was blocked if there are no visible signs?
    Cheers mark
     
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