by grunf on Mon, 13 Apr 2020 6:33 +0000
Tony2 Im sorry you feel that way. It was not my intention to be condescending in any way and I dont see where exactly was I condescending.
We were not discussing definition of DPF mate.
Its not about algorithm and dumping. There are sensors which tell car how full the DPF is, then once full, regeneration sequence starts during which the diesel gets injected in to DPF via 5th injector and all the accumulated soot burns (not simply dumped). Regeneration sequence will not start if the coolant temperature is below 71 degrees (thats why when the forced regeneration is performed engine revs up to 1900 initially, then settles to around 1200 and then to 950 until the regen is done)
If the injector gets clogged, or its housing (as it is the case with all old style design housing, just a matter of time otherwise Toyota would not go to the lenghts of making a new one) then not enough diesel is injected in to the DPF and regeneration is going to take much longer or not be completed. Which then leads to DPF not be able to reach its optimal burn temperature of around 650 to 720 (depending what stage the burn is in) which then leads to DPF cones getting clogged up and engine simply getting choked to death, as the flow through exhaust is minimal. Normal DPF pressure is around 32 whilst driving, during increased engine load or whilst regeneration is in progress it can go up to 34, if the DPF gets clogged this pressure will then go above 35 and higher, triggering a DPF warning light.
Thats bare basic, not factoring other scenarios like:
- towing
- driving in hills
- is the vehicle loaded
- driving with heavy foot
all of which then play in to how DPF regeneration is done because engine performance and its fuel delivery have more priority than DPF 5th injector and regeneration in progress, meaning lesser ammount or no fuel at all gets delivered to 5th injector during increased engine performance/load which then delays or hinders DPF regeneration.
Also position of DPF in engine bay plays large factor as well, due to airflow direction etc it can cool down DPF and make regeneration last longer. But unfortunately that can not change. For example due to all of the above, Toyotas DPF regenerate every 250 to 350 kms, whilst some other manufactures have DPF regeneration on average every 600 kms and it is done much quicker (Isuzu or Mitsubishi)...
Hope this helps.
Maybe we are talking about same thing, just saying it differently...
Have a good day.
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