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2004 A3 2.0 TDI juddering and struggling to start?

Discussion in 'A3/S3/Sportback (8P Chassis)' started by gizm0, Dec 11, 2010.

  1. gizm0
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    gizm0 Member

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    [Dec 11, 2010]
    hi guys i have a 2004 A3 2.0TDI on about 100k, the car sounds like its struggling to start and sometimes taking a couple of attempts to start, also when sitting on idle the car is juddering really bad, iv had a new fuel filter as the old one was really blocked up and a new throttle body, had it checked for faults but none were showing, has anyone had this problem or any suggestions for me to try to fix it.

    thanks in advance

    Dan
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  3. devonmikeyboy
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    devonmikeyboy As far from JBS as possible !

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    [Dec 12, 2010]
    EGR could be blocked with **** plus you could try a good dose of injector cleaner.
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  4. gizm0
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    gizm0 Member

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    [Dec 12, 2010]
    ok cheers ill try the injector cleaner and get someone to look at the egr valve, im usually good with cars but dont know my way round these engines lol

    anything else worth checking guys?
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  5. mike foster
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    mike foster Fossie VCDS Map User

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    [Dec 12, 2010]
    Injector wiring loom ?
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  6. gizm0
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    gizm0 Member

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    [Dec 12, 2010]
    could you expand on that abit please? what could be wrong with it?
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  7. mike foster
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    mike foster Fossie VCDS Map User

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    [Dec 13, 2010]
    If you search this forum for threads regarding juddering and rough idle you will eventually find that in a large number of cases the injector wiring loom is at fault. Apparently some of the looms were subject to intermittent failure for some reason or other and I believe Audi introduced a revised version at some stage.

    It is not that expensive to buy and, from all accounts, is relatively easy to fit although I am in the fortunate position of not having had to do this job.

    Hope this helps
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  8. jameshughes1974
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    jameshughes1974 Member

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    [Dec 13, 2010]
    How old is the cam belt on it?
    My car was quite lumpy on start up until I changed the cambelt.
    If you do a serch for Torsion value you should find posts on lumpy idle.
    The cambelt can stretch a little over time which can push the timing out slightly.
    Or it wasnt set up properly when the new belt was fitted.
    Vagcom (VCDS) or the like can measure the value and adjustments can be made as the cams on this car can be slackend off to
    1. Help fit the belt in the first place
    2. Allow a slight adjustment to get the "Torsion value" correct.

    Best watch my spelling of Torsion as well - Audi may spell it different to me!
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  9. gizm0
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    gizm0 Member

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    [Dec 14, 2010]
    I did search the forum but wanted to know if there was anything more simple that could be causing it.

    Off the top of my head I can't remember how old the cam belt is but would this cause the car not to start first time?

    It Took a couple of attempts to start again last night :'(
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  10. jameshughes1974
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    jameshughes1974 Member

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    [Dec 15, 2010]
    Does it start really well on a stone cold engine?
    but warm or hot it takes two goes?
    There are two starter related problems (but not lumpy idle)
    1. heat damaged starters makes them weak
    2. Audi have a hot and cold map in the ecu for starting
    When the engine is in the hot map it can be tricky to start most of them.
    I stripped mine and cleaned and greased it - that helped but didnt elimate totaly as compared to other make starters there pretty clean on the inside.
    some people have had the map adjusted by audi or when getting a aftermarket remap
    On a warm engine just try the starter once - they may be a pause followed by a climb to idle revs - works for me.

    Rough idle is a different fault though
    you have had all the right suggestions for that - there wont be anything simpler.
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  11. jameshughes1974
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    jameshughes1974 Member

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    [Dec 15, 2010]
    And when you say throttle body what do you really mean as diesels dont have a throttle body as such.
    they do have the valve that closes in the air intake when the engine is shut off - do you mean this?
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  12. gizm0
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    gizm0 Member

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    [Dec 15, 2010]
    Ok cheers for the suggestions, it does struggle to start alot when hot. But it does also struggle sometimes when cold? Could it be something to do with glow plugs? I'll be filling up in a couple of days so I'll put some injector cleaner iv got.

    Yeah sorry it was a valve at the front of the engine?? (I didn't change that myself someone done it for me n I watched lol) but it was full of gunk!! This didn't really make much difference though...

    Thanks for the advice so far guys :)
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  13. gizm0
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    gizm0 Member

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    [Dec 15, 2010]
    Ok cheers for the suggestions, it does struggle to start alot when hot. But it does also struggle sometimes when cold? Could it be something to do with glow plugs? I'll be filling up in a couple of days so I'll put some injector cleaner iv got.

    Yeah sorry it was a valve at the front of the engine?? (I didn't change that myself someone done it for me n I watched lol) but it was full of gunk!! This didn't really make much difference though...

    Thanks for the advice so far guys :)
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  14. NHN
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    NHN Retrofitter - Audi - VW - Skoda - Seat Site Sponsor VCDS Map User

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    [Dec 15, 2010]
    Which did you use on your bkd's Mike?

    Intake manifold flap you're referring to, although they may have swapped this, did they remove the egr & clean this fully & test ok, did they also check the egr cooler actuator at rear of engine, check glow plugs functions with vagcom?

    Starting **** when hot is usually 1 of 2 issues, coolant sensors or starter, the starters suffer from heatsoak given its strapped to the gearbox which gets fairly hot from use, thus the starter is almost a heatsink & affects possibly the coil/solenoid, I have fitted new starters to some bkd's & the new starters were a hell of a difference, also a DIY swap aswell, somethings to consider aswell as injector problems which have affected these cars too.

    Glowplugs wont affect a warm engine as they're just used on cold blocks to heat the cylinders as such, so wont be used all the time, for me its not this your problem mate, probably one of above to check.
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  15. gizm0
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    gizm0 Member

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    [Dec 22, 2010]
    im going to be gettng the alternator and injector wiring loom off someone i know, but hes saying theres two looms available? could anyone help me out with chich one i need or possibly give me a part number?

    cheers

    Dan
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  16. gizm0
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    gizm0 Member

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    [Dec 22, 2010]
    im going to be gettng the alternator and injector wiring loom off someone i know, but hes saying theres two looms available? could anyone help me out with chich one i need or possibly give me a part number?

    cheers

    Dan
    #15
  17. gizm0
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    gizm0 Member

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    [Dec 22, 2010]
    also i heard someone mention about a sensor at the back of the engine to try unplugging and seeing if it starts ok then? could anyone tell me where abouts its located and if its accessible from just opening the bonnet?

    thanks guys :)
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  18. mike foster
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    mike foster Fossie VCDS Map User

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    [Dec 22, 2010]
    The BKD engine injector wiring loom is part number :- 03G 971 033 L
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  19. gizm0
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    gizm0 Member

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    [Dec 22, 2010]
    thanks :) what does BKD mean? sorry lol (newbie here) lol
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  20. PW-Motorsport
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    PW-Motorsport Member

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    [Dec 22, 2010]
    Dan
    As suggested by James above.
    If the cam belt has stretched a little, the cam/injector timing will be out. This will cause a poor start, without fault codes.
    If the belt has been changed without using the correct crank tool and cam pins, the timing references will be from the old belt.
    I guess at 100k it has had a belt and water pump change? Check under the covers to see if there is any tipex marks on the pulleys, if there is it would suggest the belt has been changes without the correct tools?

    Also have the garage do a block test to check if you have any CO2 in your coolant, this could indicate the onset of a cracked cylinder head. This would give a poor idle quality when started.

    Faulty heater plugs will throw up a fault code.
    Last edited: Dec 22, 2010
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  21. mike foster
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    mike foster Fossie VCDS Map User

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    [Dec 22, 2010]
    All engines have a code and if you look inside the front cover of your service book you will see against engine code the letters BKD.
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