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A4 TDI no power when cold and slight coolant loss

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by lukefaichney, Jun 21, 2012.

  1. lukefaichney
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    lukefaichney New Member

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    Hi,

    Audi A4 2.0 TDI 140Bhp, 2006, 117000 miles

    I've been reading through some of the excellent articles and replies on the forum, am looking for some advice before I goto to garage and get told something which might cost me money and not fix the issue. My symptoms which started a couple of months ago:

    When the car is cold for the first few minutes it sounds kind of boxy and hesitates to accellerate past 3000 rpm, feels like its struggling for air.

    No smoking issues when hot or cold or when experiencing this issue
    No warning lights
    Fuel consumtion seems to be slightly off but not too noticeable (no trip computer)
    Losing the smallest amount of coolant, difference between max and min over around 900-1400 miles (not entirely sure) no visible leaks, no water from exhaust, no white smoke. Car never used any coolant whatsoever before this issue started.


    One of the guys had an issue on the 170Bhp model, wondering if mine could be similar as not all the symptoms match and my car has had no modifications:

    http://www.audi-sport.net/vb/audi-s...-170-tdi-odd-engine-noise-now-pics-turbo.html

    I might ask a local guy who is more capable to check for coolant leaks as in the above article.

    Does anyone have any 'know what that could be' suggestions. I use the car for work, 40K miles a year and am struggling to afford to run it as it is having to replace the clutch and flywheel at 100K.

    Many thanks
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  2. lukefaichney
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    lukefaichney New Member

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    Is there anyone who might like to reply to my post please?
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  3. Lee Applin
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    Lee Applin Guest

    regards to the cold start id try a new engine temp sensor, you can test them with a ohm meter but you would need autodata to see the required outputs, or you could just change it prob £30


    it tells the ecu if engine hot/cold and it adjusts accordingly, some cars have one sensor with 4 wires, some two sensors one for ecu one for fan etc
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  4. lukefaichney
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    lukefaichney New Member

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    Got it on the diagnostics machine yesterday. It's reporting "Boost pressure regulation exceeded (Overboost condition)".

    I've been told this could be the N75 valve or that the the vanes on the turbo or getting stuck. Going in next week for the valve and will report back.
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  5. Lee Applin
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    Lee Applin Guest

    that will be nothing to do with starting issues, did they clear the code and get you to rag it round the block and re read? could of just been an old code lingering about


    did they look at the live data and see what the sensors are reporting actual over desired?
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