Diesel MAF-sensor?

[Michael D. Porter]

Gary W Harris wrote:
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> Text item:
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> What about measuring the fuel flow--since the Dudsel operates at WOT, one could
> use RPM/VE to calculate airflow (similar to a EFI MAP system), throttle position
> to measure fuel flow, thus get some reasonable approximation allowing
> particulate emission control.-- or perhaps fuel flow/injection timing needs to
> modulated to control particulates
> Gary, the latest electronically-controlled heavy-duty diesels modulate 
injector timing to control fuel flow.  Most, upon start-up, use a 
modified MAP sensor to establish a baseline for ambient atmospheric 
pressure and ambient air temp, then, after start-up, the MAP only reads 
turbo boost in the intake manifold.  Most run primarily from a limited 
number of sensors, including fuel pressure, and a heavily-mapped 
operation cycle to include smoke reduction modes, etc., based on feedback 
from the transmission and the throttle potentiometer.  

The mass air-flow sensor used in the system I mentioned was linked to a 
Ford computer which, I think, was used mostly to calculate inlet air 
volume.  Pre-programmed into the computer was a routine to initiate 
heating of coils in ceramic disks which heated to a temperature capable 
of burning off trapped particulates.  It worked badly, and was finally 
replaced by catalytic converters which work much more reliably than this 
system ever did.  I used that example simply to illustrate an awareness 
of the problems associated with air flow through a MAF sensor. 
Cheers. 
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