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misfire after other problems

Jonion May 10, 2012

  1. Jonion

    Jonion Member

    Hello folks, long time no see.

    Well unfortunately the Quattro is yet again the bane of my life and I need to get it sorted or get rid of it.

    So I'll go through the scenario/timeline as best I recall and then get on to the current problem.
    Car 1998 Quattro 2.8l 30v V6 Avant

    It has a burning oil smell occasionally after a run.
    Gave it a service. No problems as such from that lol
    Had a fuel leak from the filter so changed that out. I still have a leak but could either be cracked tank or more likely a **** crush washer on the filter. Not had chance to swap a new one in yet as the current problem appeared.
    Cleaned out the breather pipes as they were gunked up as I expected.

    Occasionally it would have a small misfire but nothing regular or really problematic.
    After filter change it started as normal but due to leak never took it off driveway.
    So after sitting a few days it would to start albeit a bit rough and would clear a little if revved. Then became harder to start and is obviously not firing on all cylinders at any time.
    All plugs were a little sooty so cleaned them and swapped them around but no real difference.
    I have checked it with a cheap scanner and nothing, checked with my Vag-Com and that reports no codes.

    so I'm after any ideas as to common faults that may cause this or something I've simply missed.

    I am at the point where I will not throw money at it as it's had enough already, so I need to track the problem first.
    My current thinking is to just sell it, probably as parts. Seems I spent more on the exhaust than the thing is worth.

    any wise words appreaciated, cheers.
  2. Jonion

    Jonion Member

    Well I'll update this even if no-one's interested.

    So started slightly better today but still missing and undrivable.
    Pulled plugs to see what difference and none of them made any more difference than any other really so likely not to be coil/lead/plug issue.

    If anyone who knows these engines better sees this I am curious if this is normal...
    After it has run there is a distinct noise (almost like a small electric motor running) somewhere on/around the throttle body, this is more apparent if you open the throttle by hand. After a while it stops.

    Maybe something in the supply chain...
  3. S4_dan

    S4_dan Fire up the Quattro! VCDS Map User

    The struggling starting will most likely be due to fuel leak. Fuel will drain back from engine, hence getting a bit better when rev it (pulling more fuel through, along with air possibly)

    Sort the fuel leak out and then go from there.

    The oil burning smell will most likely be oil dripping onto the manifold/exhaust system somewhere. Go for a hard drive, pull up and look under the bonnet for where smoke is coming from.

    The motor like noise you can hear is the throttle body. If you have had the throttle body off, you will need to realign it using VCDS. I think you can also do it by having the bonnet up, drivers door open. Turn ignition and leave. You should hear the TB whining, setting itself up.

    My 2.8 V6 developed a misfire. So intermittent that it couldn't replicated. I never got to the bottom by my suspicions were on the coil pack! Once it got warmed up, it tend to get worse. Even the new owner drove it to Blackpool as it got worse the longer he drove it.

    Do you have any DTC's coming up with vag-com/vcds?

  4. Jonion

    Jonion Member

    Cheers Dan.
    Oddly it was the fuel leak I was fixing when it started doing this, was running fine while it was leaking though lol
    In fact it started playing up as I went to move it to do the fuel filter crush washers.
    So not done them yet, might do them anyway just in case that is causing the problem.

    The oil smell is only after a bit of hard use and there is never any visible smoke.

    So the noise from the TB is normal then, at least that's one thing I can ignore then :)

    Stil no codes showing on VCDS, even with it running like **** it gives no codes.
  5. jcb

    jcb Active Member

    I have a similar smell from the left hand bank of the engine, it is the rocker cover gasket leaking oil down the side of the engine.
  6. Jonion

    Jonion Member

    Still not had a chance to take a look at this.. because I have some pos French thing that has taken over as the biggest bane of my life.
    Why do Renaults come from the factory with a time delay fault list? /rhetorical

    anyway after I spend the weekend with a nice reliable Honda racecar I'll be getting the Audi looked at... will let you know how it goes.
  7. murran

    murran Well-Known Member

    get it on the road and have a good drive in it.
  8. Jonion

    Jonion Member

    The chance would be a fine thing.
    I've never owned such an unreliable car.
    Bought as a workhorse to keep the miles down on my trackday car... ironically my trackday car has been used to rescue the Audi on numerous occasions lol

    Might just strip it and sel it for spares.. probbaly worth a hell of a lot more that way as well with the stainless exhaust, nice wheels etc...
  9. adesb5

    adesb5 Member

    oil leak is due to the two sensor type things on the back of the heads near the bulkhead there a ***** to change do it when you change the cam belt,theres a additive to put in the oil that freshens up the seals and will stop the leak, try it it may work,misfire is probably due to the coil/leads breaking down.

    where are you?? near leicester? i have a spare set of leads and coil pack if you want to try them.(there not for sale and i wont post them out sorry)
  10. Jonion

    Jonion Member

    Cheers for that offer, I'm not too far away (on the A5/M42 junction) so I'll bear the offer in mind when I get to doing it.

    Shame about those possible sensor leaks, the cambelt etc was done just after I got the car about 2 yrs and about 2k miles ago.
  11. adesb5

    adesb5 Member

    ive got a boat moored at alvecote,so no probs

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