[Diy_efi] trying to replace standard flap style afm with MAPsensor

[Adam Wade]

--- WopOnTour <wopontour at hotmail.com> wrote:

> Actually a speed-density system (using a MAP sensor)
> is still determining MASS of the air entering the
> engine (as does a MAF based system).

Two corrections:  A MAF system is attempting to
MEASURE the mass of air entering the engine (and
really only needs correction for how much of that air
stays in the combustion chamber, and how much end gas,
assuming that it's a directional-flow type sensor),
whereas a speed-density system attempts to CALCULATE
the air mass based on temp, density, and pressure drop
to indicate flow rate.

The second is more general; the system being discussed
initially uses a volumetric airflow sensor, or VAF as 
call it; the flapper-type VAF that was used so widely
on the Bosch L-Jetronic system (as well as the Datsun
system used in their earlier Z cars, and the one used
by Kawasaki for a number of years) also attempts to
measure flow RATE and then CALCULATES air mass based
on temp and sometimes ambient pressure as well.  I am
unsure of how the response curves of a MAP sensor
compare to those of a VAF sensor, or how you would go
about converting one to the other off the top of my
head; I also suspect that increasing the fueling
capacity of the injectors in that system by more than
50% is the ultimate cause of the inability to achieve
a proper amount of injected fuel under no load.

| 82 Honda CX500 Turbo (Cassandra)  90 Kwak Zephyr 550 (Daphne) |
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|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |
| M/C Fuel Inj. Hndbk. @ Amazon.com -  http://tinyurl.com/6o3ze |

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