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Testing Dumpvalves

Discussion in 'A4/S4 forum(B5 Chassis)' started by tonybolony, Aug 31, 2013.

  1. tonybolony
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    tonybolony Member

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    [Aug 31, 2013]
    Is there way to test if DV are failing?

    I have fitted a Boost Gauge as i was sure my car wasn't boosting fully, and i can now see that its getting to about 0.5 Bar or under and cant hold it, i have checked and listened for leaks, i also disconnected the MAF in case that was been a divvy, so i am now thinking DV's ? they are the originals and have covered 164,000 and are 15 years old.
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  3. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    [Aug 31, 2013]
    Pull them off and blow through the side port if you go red there fine if you can blow through it replace them !!
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  4. S4 Muzza
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    S4 Muzza oww! my giant blue head!

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    [Aug 31, 2013]
    Use a pen or something to push the piston up from the bottom and cover the top hole with a finger. If the piston stays where it is all is good, if it slides down its not holding pressure.

    bulletproof methodology.....
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  5. tonybolony
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    tonybolony Member

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    [Sep 1, 2013]
    so i tested my DV's and i push them to the top cover the hole and they drop about half way back down, then i let my finger off and they plop totally back down, so i am guessing they work, or should they stay right at top and not come down at all?

    My Boost gauge shows vacum 0f about -7 -8 on idle.

    i cant hear any leaks so i am totally stumped :-(
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  6. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User

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    [Sep 1, 2013]
    Have you scanned the car for faults? It sounds like limp mode. I assume you have a 2.7?
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  7. tonybolony
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    tonybolony Member

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    [Sep 1, 2013]
    no just downloaded the VCDS Lite so i will try a scan later

    yes it is a 2.7 Bi Turbo
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  8. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep VCDS Map User

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  9. tonybolony
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    tonybolony Member

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    [Sep 1, 2013]
    not sure what you mean by smoke test, if your refering to if my turbos smoke at all they dont, i get nothing out the back of the car other than the usual :)
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  10. S4 Muzza
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    S4 Muzza oww! my giant blue head!

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    [Sep 1, 2013]
    #9
  11. tonybolony
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    tonybolony Member

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    [Sep 1, 2013]
    well as i put on a new thread these are the faults i got

    As discussing an earlier thread these are the log readout for my car.

    The engine has been out, due to blown turbos which i replaced

    as i said the units are firing up but not past 0.5 bar and the boost doesnt always hold, naturally the faults standing out are the boost pressure control valve and the purge valve, have i done something wrong :-(

    11 Faults Found:


    17833 - EVAP Purge Valve (N80): Short to Ground


    P1425 - 35-00 - -


    17938 - Cant Find


    P1530 - 35-00 - Please Register/Activate


    17955 - 17955/P1547/005447 - Boost Pressure Controle Valve (N75): Short to Ground


    17697 - Boost Pressure Control Valve (N249): Short to Ground


    P1289 - 35-00 - -


    16486 - 16486/P0102/000258 - Mass Air Flow Sensor (MAF/G70): Signal too Low


    17861 - Cant Find This


    17865 - Exhaust Gas Temp Sensor 2 (G236): Open or Short to Plus


    P1457 - 35-00 - -


    17523 - Cant Find This


    P1115 - 35-00 - Please Register/Activate


    17527 Cant find this


    P1119 - 35-00 - Please Register/Activate


    16518 - Oxygen (Lambda) Sensor B1 S1: No Activity


    P0134 - 35-00 - -


    16538 - 16538/P0154/000340 - Oxygen (Lambda) Sensor B2 S1: No Activity
    Last edited: Sep 1, 2013
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  12. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User

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    [Sep 1, 2013]
    At least 3of them would cause limp mode. Especially 02 sender egt and maf. I'd check fuses because an awful lot of fault s there that bi believe share a fuse.
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  13. tonybolony
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    tonybolony Member

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    [Sep 1, 2013]
    what if i have got the earths wrong, as in ones on engine should be on chassi and vice versa, or would that not matter?
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  14. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User

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    [Sep 1, 2013]
    shouldnt do no, as long as the body is connected to the engine it should be ok. I assume you havn't perhaps trapped a wire in between anything when you had engine out?
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  15. tonybolony
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    tonybolony Member

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    [Sep 2, 2013]
    well i dont think so i will have to have a good check over
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