Hi: New Member, how much particulate build up will occur in the DPF

Discussion in 'VW Mk6 Golf, Jetta, Beetle, Sportwagen TDI forum' started by PaulReif, Jan 18, 2012.

  1. PaulReif

    PaulReif New Member

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    Jan 17, 2012
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    Car:
    2009 TDI Jetta Sportwagen
    I recently purchased a 2009 TDI Jetta Sportwagen with 26,000 miles and I have nothing but praise for it and no problems. I drive a mix of highway (20) miles and city daily and have some question about how much particulate build up will occur in the DPF as a result of my city drives. In the three months I have owned the car I have had 2 brief regenerative DPF burns that caused the high speed fans to run for 10 minutes. Both occurred during short city drives. Hopefully this is not unusual. I very much appreciate the wealth of technical info available on this site, it has given me a better understanding of the TDI powerplant. Thanks
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  2. chittychittybangbang

    chittychittybangbang Administrator

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  3. wimpog

    wimpog Member

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    I've owned the vehicle for almost 3 months already, and commute to work every day 40 minutes one direction. Either I have not noticed, or it has simply never happened to my vehicle yet, but I don't believe it has gone through a DPF regen cycle. Are there other indicators, like dashboard lights? Should the yellow filter dashboard light come on, when this happens?

    On a related topic, here is my hypothesis, please correct if I'm wrong.
    Keeping lower RPMs not only wears your engine less, and prolongs its life, but keeps the DPF cleaner, prolonging its life. Since diesel fuel burns slower, on high RPMs it will not completely burn, hence more waste, and the DPF get clogged faster. But if RPMs are kept lower, when possible, it allows the fuel to burn well, and minimize the waste. Am I correct?
  4. chittychittybangbang

    chittychittybangbang Administrator

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    No indicator. Yuo may notice temporarily higher power/better response, odor at stoplights, fan running after car shut down.

    lower rpm isn't bad withing limits, you also have higher load/oil pressure vs. higher engine rpm, so in theory it puts more stress on engine. Never lug the engine.
  5. PaulGiz

    PaulGiz New Member

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    Nice theory, but no basis in fact.

    Diesels run well under load, but don't overdo it. You will get clean efficient combustion at all engine speeds

    Higher revs, and occasional blasts through the gears keeps turbo vanes loose and exercised, exhaust manifold clean and helps seat your piston rings properly (it takes about 50,000 miles or more to achieve full compression on a TDI).

    The best thing to do for your engine is to drive it normally. It's also more enjoyable.

    P.

    Sent from my Sensation using Tapatalk
  6. wimpog

    wimpog Member

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    What do you mean "no basis in fact"? Diesel doesn't burn well in high RPMs. Where did you get the 50,000 miles from?
  7. speedracer1407

    speedracer1407 Member

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    2011 Golf TDI
    I think the point is that higher RPMs with a TDI doesn't produce more soot, regardless of how slowly Diesel burns.

    Consider this:

    Diesel engine's don't rev very high to begin with. With the TDI, you're talking about a power band that doesn't extend much past 3500 RPM, which is slow enough that diesel burns just fine.

    Also, a new TDI's piezoelectric injectors also fire multiple injections during a single combustion cycle, which helps maximize the efficiency of each combustion event and leverages diesel's slow-burning tendencies.


    As mentioned, turbo diesels run best under high load in the meat of the powerband. A TDI will produce more soot lugging off-boost at low RPM. You can observe this, as I do on a daily basis, by watching, say, a city bus accelerate from a stop. Without fail, the bus produces a cloud of soot initially until the turbo spools up and stops producing visible soot.
  8. PaulGiz

    PaulGiz New Member

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    1. Common rail TDIs have piezoelectric injectors which do multiple shots, controlled by the ECU for efficient combustion over a wider range than earlier diesels. I drove trucks for years and the powerband was 300 to 500 RPMs wide (let out the clutch at 1300, shift at 1800). In addition you have two intake ports (swirl and straight) which operate at different RPM ranges to ensure complete combustion.

    2. Compression on these motors doesn't peak for 40,000 miles or more. Read this: http://forums.tdiclub.com/showthread.php?p=464223

    P.

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