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Showing content with the highest reputation on 02/10/2020 in all areas

  1. Replaced the old & tired alternator guard with a flashy CFRE one. Old New Downside: now the oil cooler guard is ugly...
    2 points
  2. 1 point
  3. Hi, on 2nd thought your comment deserves a more detailed reply. The name cold start is not well chosen. Start-up fits better. The reason why the start-up function is needed and why it's temperature and to a lesser degree revs since start dependent is the following. After pressing the starter button the injectors begin injecting fuel, the nozzle and the fuel jet are pointing towards the opposite side of the intake pipe . At that time there's almost no air flow and a very low air speed moving through the intake, hence the first fuel shots are creating a fuel puddle on the opposite surface of the intake tract. A surplus of fuel, which is caused by the trim values, during that period ensures that enough fuel gets into the combustion chamber to achieve a ignitable mixture. This effect is engine and air speed dependent, so a temporary enrichment for some revs is needed at any engine temperature. Once the engine is turning over at a higher speed, the resulting higher air speed moves more of the injected fuel into the combustion chamber. And the increasing temperature of the engine increases the evaporation of the fuel, again resulting in more fuel getting into the combustion chamber. My current conclusion, based on the measurements, is that the critical values in the start-up table are those used during the first 10-50 revs. Once the engine is running on its own the start-up table values can be replaced by fuel engine temp trim table. Cheers Meinolf
    1 point
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