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Could this be a DPF regeneration?

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by Jeeves, Sep 5, 2012.

  1. Jeeves
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    Jeeves quattronly

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    [Sep 5, 2012]
    I do a regular 280 mile journey of which over 200 are on the motorway (typical lane 3 speeds). My last stop was about 20 miles before the end of the journey, and when I stopped at my destination the fan came on. I've never noticed a regeneration before in 50,000 miles and 5 years of ownership, but could this be what it is, and what's the best thing to do now I've interrupted it?

    Forgot to say that final minute or so is crawling at idle in 2nd gear. (Allows turbo to simmer whilst on a dirt track).
    Last edited: Sep 5, 2012
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  3. Brodster
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    Brodster Shark Performance In Scotland VCDS Map User

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    [Sep 6, 2012]
    DPF regen is carried out whilst the car is in motion and has nothing to do with engine fans. A regeneration will occur when there is a build up of soot inside the cannister. After the soot builds up over time, the onboard computer controls fuel injection to allow unburned fuel to enter the filter at measured intervals where it flares off and generates increased temperatures that incinerate the accumulated soot. This soot is then ejected out of the exhaust. For this process to start certain parameters have to be met such as vehicle in 5/6th gear such as on a longer journey at a constant speed.

    what is a DPF? | DPF Removal

    Have a read
    Last edited: Sep 6, 2012
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  4. Jeeves
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    Jeeves quattronly

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    [Sep 6, 2012]
    Thanks for the info, but I've read on other forums that as a result of the burn off, the fan often comes on once the car is parked to dissipate the heat built up. I've noticed this on a MY11 TT with a CR170 engine, but obviously my A4 is a fair bit older, so I'm not sure if the mileage based regen (every 300 miles?) applies to the PD engine. I'm just wondering whether the regen has finished, or if it's been interrupted in which case I probably need to take it for a longer drive.

    Other than a stutter before the injectors were replaced, the car never drives noticeably differently, so I'm just wondering if I've just coincided with a mileage based regen (if that applies).
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  5. Brodster
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    [Sep 6, 2012]
    Didnt think there was any mileage based regeneration cycle. Could be on the newer CR versions though. Someone will be along shortly to clarify but I was always under the impression that the regen was based on the cannister being full and when all the parameters met regen was carried out.

    It could possibly be that you've interrupted the regen cycle as this takes between 10-15 mins average so would make sense from coming off the motorway as per your journey. The regen process if it has been interrupted will be resumed when regeneration conditions are once again met.
    Last edited: Sep 6, 2012
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  6. APAutomotive
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    APAutomotive Shark Performance Shropshire

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    [Sep 6, 2012]
    Regens are passive & can happen every 400ish miles.
    How long does the fan stay on for once you have removed key from the ignition?
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  7. Jeeves
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    Jeeves quattronly

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    [Sep 6, 2012]
    This was the first time I've noticed it, and the car hadn't been driven hard - just a long distance with a couple of stops. Ambient temp was about 18 degC and the fan stayed on for about 30 seconds.
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