Thanks for the reference. According to this info for diesel it's supposed to correlate directly to output torque so that should be close enough. Perhaps adjusting for RPM would give output power, which would (or should) be a more direct correlation to fuel consumption.
If it's directly related to air flow for gasoline engines it shouldn't drop to zero during DFCO, and my idea would be invalid. I'm just curious if anyone has noticed what this value does during DFCO for gas / LPG as I don't have the equipment to look at this at the moment (laptop battery is toast).
Quote:
Originally Posted by eimix
PID04 is MAF/maxMAF
for diesel engines it is something else, but essense should be same.
and probably you will be back to 14.7 at some point.
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The power output of a compression ignition engines is not governed by a throttle blade. The quantity of fuel injected in the combustion chamber is the only means of controlling engine output, and they do not operate in a closed loop stoichiometric burn mode, at least not in the same sense as a gasoline engine. Some newer "clean" diesels do have something that looks like a throttle, but is in essence part of an egr system to deal with soot.
Most diesels from 1999 and up that utilize oxygen sensors do so only to reduce smoke. But they don't operate at a fixed mixture - at part throttle cruising speeds diesels can run as lean as 22:1. That's the primary reason why the ALH TDI and some of it's successors can achieve >52MPG without hypermiling techniques in a 2800lb car.
Quote:
Originally Posted by eimix
DFCO detection is done using PID 0x11 (THROTTLE_POS) and PID 0x03 (FUEL_STATUS). For now it looks like PID 0x04 could be used too.
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I just thought it might be an easier way to detect DFCO for gas - reading two PIDs takes twice as long as one...
