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2.5tdi boost issue at 2400

Discussion in 'A4/S4 forum(B5 Chassis)' started by foursprungdugtechnique, Jan 29, 2011.

  1. foursprungdugtechnique
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    foursprungdugtechnique Member

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    Hi,
    I'm new on here and thought someone might have an idea of whats wrong.
    When accelerating there is a kind of quiet shreiking noise (Not turbo whistle) which can really only be heard in the drivers seat, it started doing this about a year to 18 months ago occasionally. Now it is all the time, light or heavy foot.

    The car feels a bit flat lower in the rev range compared to a few years ago, and when floored there is a bit of a flat spot around 1800 rpm, then when you hit 2400 rpm it sounds like the boost is being dumped.
    I have changed the Air meter, the EGR solenoid, the boost solenoid, it had a new turbo and the oil feed bracket fitted last July, this has been happening since before the new turbo (new, not reconditioned).

    The car also runs a bit rich, tailpipes are a bit sooty, uses hardly any oil between services, never had to top it up, or even got close to needing it.

    :keule:
    #1
  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    It would be worth pressure testing the inlet system to check for any splits/leaks?
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  3. foursprungdugtechnique
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    foursprungdugtechnique Member

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    Cheers for the reply, someone suggested the inlet manifold gaskets when I was speaking to them. I had a look at the air meter and it seems ok that side of the turbo, on the pressurised side... Not checked that yet, suppose there might be a problem on the offside inlet side. Would that cause rich running too?
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Yep, because air that the management system thinks is there never makes it to the cylinders.
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  5. foursprungdugtechnique
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    foursprungdugtechnique Member

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    Yeah, I see where you're coming from. If the gasket is knackered it could male a noise like someone blowing a blade of grass. Would that in turn cause the boost to be dumped as well then?
    This is my first tdi, had 80q, 90, 90q, 100cs, and 2.2 90 all 5 cyl petrols, easy to work on, this has way more plumbing on it!!
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    It could be the gasket, a split hose, split intercooler, loose jubilee clip etc etc.

    Pressure test is your first step. If you have access to a compressor there are kits on ebay.

    You also need to do a fault code scan, preferably using VAGCOM/VCDS. There are many options for that, but the cheapest is a £10 lead from ebay, the free version of VCDSLite and a laptop.
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  7. foursprungdugtechnique
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    foursprungdugtechnique Member

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    I have downloaded VCDS, need to get a lead and have a look. My mate has lead and activated copy, will get him to plug it in til I get mine up and running.
    I have a couple of options regarding pressure testing, seems to be the logical thing to do, can't hear anything under the bonnet with the engine running, and can't put the engine under load without wrecking the clutch.
    Can't wait to get it running as it should, just wish the guys who service it would find the problem, since they are VW trained mechanics
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  8. foursprungdugtechnique
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    foursprungdugtechnique Member

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  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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  10. foursprungdugtechnique
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    foursprungdugtechnique Member

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    I bought that one, will let you know how I get on with it. Been round a few garages who 'specialise' in turbo cars and to my surprise NONE had anything like this. One who does scoobies said they would have to get someone to make one if they needed to check for leaks.
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  11. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    I hate garages, they're all bloody ****, and things like this exemplify why.
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  12. foursprungdugtechnique
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    foursprungdugtechnique Member

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    Yeah, they all know how to charge the earth for not a lot of work. The local Audi dealer here is about £80+vat/hour! That's a days wages for fairly well paid people, for 1 bloody hour??
    There are some local ex-VW/Audi mechanics that have got their own places now. But the new guys in garages aint 'mechanics' they are 'fitters', it's ridiculous that we are paying that amount for semi-skilled people to look at the car.
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