1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Rough idling - has anyone ever resolved this ?

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by mm707, Mar 29, 2012.

  1. mm707
    Offline

    mm707 Member

    Joined:
    Mar 26, 2011
    Messages:
    242
    Likes Received:
    6
    [Mar 29, 2012]
    Hi,

    My 2.0 tdi 170 2007 , like quite a few others it seems, can be a bit rough idling, runs fine otherwise and is only rough now and then ( maybe about 30 - 40% of the time ) . I can see the rev counter bobbing up and down slightly. It makes me a bit concerned when stuck in traffic etc that it may cut out.

    I've noticed a few posts on here and other forums.

    Anyone here had this and been able to fix it ?

    Many thanks
    #1
  2. Ads

    Ads

    [Dec 25, 2014]

  3. deian3387
    Offline

    deian3387 Member

    Joined:
    Feb 27, 2011
    Messages:
    79
    Likes Received:
    0
    [Mar 29, 2012]
    A nackered dual mass flywheel can cause rough idle.. had this a few times
    #2
  4. murran
    Offline

    murran Active Member

    Joined:
    Aug 10, 2010
    Messages:
    1,540
    Likes Received:
    35
    [Mar 30, 2012]
    at work ive had a heavy misfire on a 54 plate bkd engined mk5 golf at the beginning of the week. using lots of coolant too.
    a previous garage had fitted a new injector in no1 a few weeks ago.......
    anyway the cylinder comparisons showed no1 cyl was way out. did a compression test, also showing no1 was down on compression.
    while i was removing the head, to my amusement, on removing the inlet manifold i saw coolant all pooled up on the back side of one of the closed inlet valves!! so the head is cracked.
    not only that once the head was off you can plainly see no1 piston is roughly 2mm lower in the bore than no4 piston is. so its obviously been hydraulicing on the coolant on start up.
    #3
  5. eddscott
    Offline

    eddscott Member

    Joined:
    Feb 6, 2012
    Messages:
    164
    Likes Received:
    7
    [Mar 31, 2012]
    MM707 - has your car gone back to Audi to have its injectors replaced?

    I noticed mine idled lumpy a couple of Saturdays ago. It hasn't done it since it had the injectors and loom changed. Might be connected might not but worth getting it done if not already just to eliminate them.

    How would a DMF affect idle? Interested to know as mine was lumpy at one point.
    #4
  6. mm707
    Offline

    mm707 Member

    Joined:
    Mar 26, 2011
    Messages:
    242
    Likes Received:
    6
    [Mar 31, 2012]
    Hi - yes it has had the injectors replaced a few months back. Doubt it's related but it has always taken a few more turns to start from cold since they were replaced.

    If the DMF was faulty would it not be irregular all the time ?
    #5
  7. deian3387
    Offline

    deian3387 Member

    Joined:
    Feb 27, 2011
    Messages:
    79
    Likes Received:
    0
    [Apr 1, 2012]
    a faulty dmf can throw the engine out of balance and give lumpy idle, it can also be intermitent depending on engine conditions
    #6
  8. eddscott
    Offline

    eddscott Member

    Joined:
    Feb 6, 2012
    Messages:
    164
    Likes Received:
    7
    [Apr 3, 2012]
    Oh right - yet another thing to worry about :D
    #7
  9. mm707
    Offline

    mm707 Member

    Joined:
    Mar 26, 2011
    Messages:
    242
    Likes Received:
    6
    [Apr 3, 2012]
    Thanks for the info - is there any way to test the dmf ?
    #8
  10. murran
    Offline

    murran Active Member

    Joined:
    Aug 10, 2010
    Messages:
    1,540
    Likes Received:
    35
    [Apr 3, 2012]
    ^^^^ second hand engine came today. its pretty much all stripped ready to come out. just two engine mounts and drive shafts left to undo.

    dmfs you can tell by the rattling they make on start up and switch off. intermittent rattling on tickover coinciding with the shaking. also by pressing/slipping the clutch slightly while idling, does this change the "misfire" symtoms?
    apart from the above, no, its not something you can test without stripping the gearbox off.
    #9
  11. murran
    Offline

    murran Active Member

    Joined:
    Aug 10, 2010
    Messages:
    1,540
    Likes Received:
    35
    [Apr 5, 2012]
    spent most of the day on it today. all done, all seems fine. chap collected it bout half 5. definalty wasnt the injectors cus its got its originals in it and its running perfectly.
    #10
  12. A3_Mayhem
    Offline

    A3_Mayhem New Member

    Joined:
    Jun 23, 2013
    Messages:
    26
    Likes Received:
    1
    [Dec 3, 2013]
    In the case of my '56 plate BKD, injectors are the main suspect.

    Haynes manual says that they could require replacing at 60k, although I find that pretty hard to stomach.
    #11
  13. lynallbel
    Offline

    lynallbel Active Member

    Joined:
    Oct 9, 2013
    Messages:
    395
    Likes Received:
    36
    [Dec 3, 2013]
    Haynes manuals belong in the bin!
    Things have moved on a long way since they stopped being useful.
    #12

Share This Page