I don't think it was a dig at you.Originally Posted by dougmac
Anyway, I think you are limiting the scope to only what is available within the allowable envelope of the vehicle calibration, and discounting the physical capability of the HP pump. Technically, a true "100%" duty cycle of the pump would likely see it destroyed in a very short period (unless #2 Diesel were infinitely compressible, but it's not, so....). The pump itself is "dumb", only varying its output according to the flow control, which is controlled by PCM commands, according to sensory data input and programmed demands. The operating envelope of the pump is determined by the calibration parameters, not the physical capability of the pump. Demanding a 100% duty cycle of the pump is only commanding the full duty cycle allowed by the calibration, and not, necessarily, the full capability of the pump (otherwise, the upper threshold of the pump's performance would have to be identical from pump to pump, vehicle to vehicle, under every conceivable condition). It's comprehensive, according to dozens of channels of sensory data. The PCM doesn't know, and doesn't care, what the physical limitation of the pump is (unless it's incapable of answering mechanical demands, not according to calibration parameter demands). The FPR/FRPR is limited only by the vapor, AKA: the PCM, via the vehicle calibration, sensory data, emission system control, and powertrain performance demands. Moving the operating envelope (range) of the pump performance sensory data, such as John is suggesting, is nothing more than that. Simple, and perhaps a band-aid fix, but it works often enough to make it a viable solution, if only temporary. The alternative is to pony up a few grand for a repair that may not be necessary for years to come. If it doesn't work, the only loss is a little time.
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