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'Cold side' dump valve? and can you tell if its been chipped?

Discussion in 'A4/S4 forum(B5 Chassis)' started by olds_kool, Jan 30, 2010.

  1. olds_kool
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    olds_kool Active Member VCDS Map User

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    [Jan 30, 2010]
    just bought another £300 project car, 97 1.8t mechanically it seems ok (needs a new throttle body, eratic idle and wont respond with vagcom) cosmetically it looks like a shed, bought as a non starter but just needed a new transponder and a fuse for the ecu

    anyway its got a baileys atmospheric dump valve fitted between the ic and throttle body guessing the original valve is blocked off but not checked yet, should i leave it? is it safe? sounds pretty cool leaves no doubt its a turbo but not everyones taste i know

    also anyway to check if its been chipped? cant drive it on the road yet but it has the dump valve, k+n panel, boost gauge and performance exhaust but no idea if its been chipped, would vagcom tell me?
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  3. Oranoco
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    Oranoco Well-Known Member

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    [Jan 30, 2010]
    Moving the dump valve will not have a negative effect and could prolong the life of the valve as well. An atmospeheric DV isn't considred to be a great idea as it dumps meterd air out the system whcih has the knock on effect of upsetting the fueling. Quite a few people run them however without noticable impact.

    What boost are you seeing on the guage. iirc 7psi is stock so 10 or 12psi and yes it's been chipped
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  4. olds_kool
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    olds_kool Active Member VCDS Map User

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    [Jan 30, 2010]
    cheers
    cant drive as its got two flat bald tyres with locking bolts and no key!
    ill probably flog the valve and stick it back to standard wont add any value to car but might get a few quid for

    any one know if throttle body can be repaired(bodged), tried cleaning then connecting battery to set, made slight difference but fault must be electrical
    also theres no part number on it
    i remember some one swapping gubbins from a different body possibly aragorn? but search function not working
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  5. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jan 30, 2010]
    I swapped the gubbins out of a Seat 1.6 throttle body into an S4 one, but that was drive-by-wire. Wasnt any idle problems with that though, it would just drop to idle and sit there randomly.

    You could pop the ECU open if you want to check its been chipped?

    What do you mean by it wont respond with vagcom? Bad idle could be MAF, lambda, CTS or a whole host of other things, so it would really be advantageous to run a fault code scan on it.
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  6. olds_kool
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    olds_kool Active Member VCDS Map User

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    [Jan 31, 2010]
    tried throttle body adaption with vagcom but in the end 'adaption' window it says error, switching to basic settings shows an error window
    before cleaning it would cut out unless i held revs, after cleaning it hunts when cold then idles ok when warmed but cuts out after bliping throttle

    might try swapping the one off my 1.8tqs if it looks the same

    already run a scan but no codes?

    what would i look for in ecu?
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  7. Matt82
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    Matt82 Active Member

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    [Feb 2, 2010]
    did you have to buy the "full" version of vagcom to make it do adaptation?
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  8. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 2, 2010]
    The engine adapts itself anyway. Just turn the ignition on and wait, and you'll here the TB doing its thing.

    Does sound like the TB. I've never opened the manual one in the A4, but if you take th black cover off carefully, you'll probably find two carbon tracks and a metal finger, clean it all out with carb/brake cleaner and see if that helps. Just watch you dont bend the fingers.
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  9. olds_kool
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    olds_kool Active Member VCDS Map User

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    [Feb 2, 2010]
    cheers will give it a try, cars where covered in snow yesterday but tried starting with maf unplugged and idle stabalised for a bit so not sure if this means knackered maf or not

    whats a cts?
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  10. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 2, 2010]
    Coolant Temperature Sender.

    If its not a knackred MAF it could be a split hose or airleak?
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  11. olds_kool
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    olds_kool Active Member VCDS Map User

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    [Feb 2, 2010]
    ah of course cts
    will be checking for leaks shortly when it stops raining
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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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    [Feb 2, 2010]
    The easist way to check is to log MAF readings. Might be worth blowing the tyres up and trying logging it
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  13. the slob
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    the slob New Member

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    [Feb 2, 2010]
    Dont use brake or carb cleaner, they are too strong an will disolve some of the carbon, use proper switch cleaner, this will clean and lubricate.

    You can get it from maplins, RS or farnell.
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  14. olds_kool
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    olds_kool Active Member VCDS Map User

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    [Feb 13, 2010]
    worked out what was causing the idle problem, found that the dump valve was opening on idle (im guessing it shouldnt?)
    removed it and its idling perfectly
    #13

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