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Strong exhaust fumes outside and in the cabin

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by netjunkie, Feb 9, 2009.

  1. netjunkie
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    netjunkie New Member

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    Hi there all,
    i have had my A4 Avant 1.9tdi 2003 (65,000miles )checked 3 times for the same problem.
    I have really really horrible exhaust fumes coming into the cabin especially when stationary and reversing. The exhaust stinks of thick diesel exhaust fumes and despite what my garage say about "modern diesels and the diesel itself" not smelling sweet like the old diesels, I think it smells unlike any of the other diesels i see and smell on the road around me. If this wasn't the case i would accept what they are saying to me.
    If the engine is running and i load the boot the smell is unbearable as is the smell in the cabin.

    I have had the front exhaust/cat replaced and they have looked and looked. i have a full service with all audi parts They did an emissions test which it passed with flying colours. They say now they can see i have a problem but can't really suggest a fix, just put the air on recirculate when stationary or reversing and maybe try a fuel additive to help clean up the emissions.

    The other thing is i think it is a little to sooty when driving aggressively. Again they just say this is normal - but this is not normal on the a3 and vectra i drove (work pool cars) on recent work trips.

    I think this is an issue that surely can be fixed - could you guys please suggest what i should ask them to investigate further.

    Many thanks,
    netjunkie
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  2. evilscotsman
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    evilscotsman Space Cowboy

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    does sound like its overfuelling, has it been remapped?

    And has the exhaust been replaced with a straight exit or sports one? The originals point to the ground to combat sootiness getting into the cabin, maybe your boot seal is torn or loose too...
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  3. netjunkie
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    netjunkie New Member

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    hi thanks for the reply.
    it hasn't been remapped. The exhaust is the original one and the boot seal is in perfect nick.:(

    i just don't know! i suspect this is why the garage can't find the cause either.

    Thanks again.
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  4. PW-Motorsport
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    PW-Motorsport Member

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    Are all the bulkhead seals in place?

    If the long seal strip that seals the heater intake battery area is missing or badly fitted, engine fumes may enter the heater box.

    You may have a split hose in the engine bay that may be not helping?
    #4
  5. Caesium
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    Caesium My BM is fixed!

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    Sorry but that's a red herring in my opinion, how would exhaust fumes be escaping from under the bonnet? No hoses carry exhaust fumes either.

    Inside your boot on both sides are exit only vents, one on either side in the well behind the wheelarch, check to make sure they are sealing properly.

    see this picture, its the thing that looks like a vent, its the only place exhaust gas can get in.
    [​IMG]
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  6. netjunkie
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    netjunkie New Member

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    Hi there thank you.
    is the seal strip you're talking about the seal that the battery cover slips into?
    split hose(which hose)?

    and any ideas why the car's exhaust is really so fumey and unbearable to be around?
    thanks again,
    netjunkie
    #6
  7. NHN
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    NHN Modmetractor

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    Chris has a good point tbh as those vents are pretty much right above the exhaust area, so not completely beyond comprehension, check cause my mate had a broken one on his Golf which pissed water in round the boot which could aswell put fumes in car, speculating but its free to check that huh, his was from a knock the car had before he bought it so wasnt aware of any damage until then.
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  8. PW-Motorsport
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    PW-Motorsport Member

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    You will get engine fumes from split crankcase breathers etc.

    These may be drawn into the heater box via the heaterbox air intake which is in the bulkhead. The pollen filter may help to trap some of the soot but not the fumes.

    You suggest the fault is less when you select recirc?
    #8
  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    i think you need to discern wether the smell is getting inside the car thru the heater or from the vents.

    It seems odd to me that if the car has positive pressure inside it, ie the blower is blowing air in, that exhaust fumes could sneak in the vents, when the pressure would be blowing air out the vents

    Try recirc mode to see if that helps, and have a good sniff/look/listen around under the bonnet with the motor running to see if you can source any leaking exhaust under there.

    Might also be worth trying different fuel, if you havent already.
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  10. PW-Motorsport
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    PW-Motorsport Member

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    You have a battery cover that slots into the lower windscreen trim and you have a long rubber strip at the leading edge of this trim. This will seal this area when the bonnet is down.

    If you have any underbonnet fumes they will be drawn into the car if this is not sealing correctly. This will be more evident when you are not moving as the airflow through the engine bay is poor.

    As suggested above, you have positive pressure in the car when the fan is on, so the air outside would have to be at a greater pressure to enter the car via the boot vents. As they like work oneway reed valve.
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  11. Caesium
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    Caesium My BM is fixed!

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    Crankcase breather fumes are totally different to exhaust fumes, they smell totally different. If a breather hose were off you'd see loads of oily deposits around the area it was split/disconnected.

    Open the boot after a run and have smell in there, the air recirc wont eliminate the fumes if they're coming in from the rear.
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  12. PW-Motorsport
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    PW-Motorsport Member

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    EGR valve ?
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  13. netjunkie
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    netjunkie New Member

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    Hi guys and thanks soo much for all this.

    to clarify the fumes are coming in through the heat vents so when i recirculate air i can not smell the fumes. i was just saying if i have the blower on i may not get fumes straight away but if i reverse i will nearly always get the fumes. I get fumes with the heater on about 96% of the time.

    so 2 issues. the dreadful exhaust smell - it is worse than other diesels and the fumes entering the cabin.

    Thanks again guys.
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  14. Caesium
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    Caesium My BM is fixed!

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    If as you say its coming in through the vents then its most likely to be coming from under the bonnet, I'd be suspicious if the garage hadn't found anything though.

    As PW says, the only thing that could be kicking out a stink under bonnet is the EGR or the PCV, I'd be inclined to check those. The PCV and the EGR can both get shitted up over time and should be cleaned on a service but normally get missed.

    Check them out.

    (I do apologise to PW as I did not know this was coming in through the vents until now, although PCV smells totally different to exhaust fumes but I assume the OP does not know the difference)
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  15. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Our car had a broken breather pipe which caused nasty oil vapour smell to get into the cabin when stationary, but as said, that smells nothing like exhaust fumes...
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  16. netjunkie
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    netjunkie New Member

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    thanks so much for that i will ask the garage to check these out. as i said they did conduct an emissions test and said it "came well within MOT limits" - does that mean very much? could it still pass but have a pcv/egr problem? are these expensive to replace?
    and lastly i think too they should look at the air intake seal (battery cover) going on what is being said.

    thanks so much guys.
    netjunkie
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  17. evilscotsman
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    evilscotsman Space Cowboy

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    when I had that sealing strip off during battery replacement mate, it did stink in the car but its an oily smell, not obviously diesel - mines a petrol, but it isnt exhaust fumes - just as the other guys are saying, its oil deposits burning.

    Smell the actual exhaust when its warmed up and see if that smells the same as whats coming thru the vents. Cup your hands in the fume then smell them if you dont want to sniff the exhaust directly, and dont breathe deeply! Engine oil burning has a very different smell to the parraffin sort of smell a diesel exhaust has.

    I suspect its not exhaust fumes, and they are looking in the wrong area for the problem. A split PCV breather hose or oil leak onto a hot exhaust part.
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  18. netjunkie
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    netjunkie New Member

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    Hi there all - and thank you again,
    i have just been over to the car and noticed when reving i can see a whole load of diesel or oil came out of the exhaust and splatted on the ground. I'm guessing it was diesel.

    Had a look at the seal and that seems fine but the actual cover to the battery does not seem well seated.

    the engine smelt of the smell i have been talking about all this time (had the bonnet up whilst reving).

    hope this can help shed more light on matters?
    thanks again,
    netjunkie
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  19. PW-Motorsport
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    PW-Motorsport Member

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    I think you need to take it to a dealer or a good independant VW/Audi Garage,
    for them to look over it.
    #19
  20. Tinners
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    Tinners Member

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    It sounds like I had the same problem. Turned out to be a split crank case breather. 5 mins for a garage to change.
    #20
  21. netjunkie
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    netjunkie New Member

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    just to let you know - i insisted they replace the seal that separates the battery and heater area from the engine. this was 2 days ago and i don't seem to have the fumes coming in to the cabin anymore.

    the garage has also noticed a fracture in the new bosal cat i had fitted a few months ago ( i had hope this would solve issues back then as the audi one had blown and my pollen filter was black). Anyone got suggestions on other brands should they not beable to get hold of a bosal replacement?

    So I am hoping that things are now on the mend and thanks very much for all your suggestions - without them I don't think I would have had the seal replaced!!

    Hopefully that broken cat might explain the strong exhaust?

    thanks again,
    netjunkie
    #21
  22. evilscotsman
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    evilscotsman Space Cowboy

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    definately! I never heard of that happening before so wouldnt have suggested it, but there you go!

    I must admit if I pull up in a puddle on the rhs the cat gets a soaking and hisses violently - oops - must watch that, its probably what happened to yours.

    See - cats dont like getting wet after all....
    #22

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