440i Exhaust clean/sooted

Discussion in 'General chat' started by Wynne71, May 9, 2019.

  1. Wynne71
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    Wynne71 Site Supporter

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    I was following a 67 plate 440i coupe this afternoon, lovely looking thing in flat grey.
    My headlights caught the exhaust pipes and I was a little surprised to see the NS pipe was spotlessly clean and the OS pipe was black with soot/exhaust residue. Why would this be? I could see a butterfly valve in the NS, does this open over a certain throttle setting? If so it would suggest the owner hasn’t been giving the car a good and proper drive....
     
  2. snrbrtsn
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    snrbrtsn WARLORD Site Supporter

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    I believe that’s how the system works
    The flap switches off the exhaust on the pavement side to prevent polluting the walkers
    When the revs are up the flap is opened and the exhaust has less restriction
     
  3. Wynne71
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    So they would reverse that system on the continent and in the states? Seems like a lot of additional cost. Unless the system is easily interchangeable.
     
  4. kleynie
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    kleynie WARLORD Site Supporter

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    Mine has the same system but I’m pretty sure the pavement side is the default.
     
  5. Spuffington
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    Spuffington Moderator WARLORD Site Supporter

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    Mine is the same on the Macan. It's a quad exhaust, the two outer tips are very sooted compared with the inner ones and the nearside one is much sootier than the offside. It's particularly noticeable when cold at how the exhaust system works as it will pour condensate out of the nearside pipe compared with the others until warmed up.
     
  6. Johnny Grabble
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    Johnny Grabble Site Supporter

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    Also the same on the G30 petrol models including the 530e, but as per @kleynie 's note, the nearside soots up first.
     
  7. Verbarthe
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    Verbarthe WARLORD Site Supporter

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    Drivers side on my 435i Convertible always soots up first , the other side does nt come into play until you put your foot down , then it s woo hoo time .:)
     
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  8. Peter
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    Peter WARLORD Site Supporter

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    My car is too old for exhaust flaps, both pipes are black. :D

    In the old days you could look at the exhaust colour and know if the mixture was good and lean. Now DI petrol engines have dirtier pipes than diesel. :rolleyes:

    Peter
     
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  9. Harry
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    Similar on the X6M. Two pipes each side, only one open on each side unless you select M mode and/or kick the bulkhead. The secondary pipe on each bank is slightly less in diameter and the arrays are not symmetrical Gtechniq metal cleaner and the finest gauge wire wool (I thinks it's 0 or 1 rated) brings them up a treat.. This was recommended by the detailer. They get pretty sooty pretty quickly.
     

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