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Input Devices:
Crank Position Sensor tells the ECM where
the piston is in the cylinder
and what stroke it is on, so that
the ECM knows when to fire the spark plugs
and trigger the injectors. It is also used to indicate RPM's of the
engine.
In a sense the crank sensor is like a set of points where as it "fires"
the engine on
time.
On carburetted bikes that is all the crank sensor does is fire the
ignition
and give RPM data. When the ignition system is timed
with a crank sensor,
it is known as a "crank triggered ignition".
Throttle Position Sensor tells the ECM how
much
the throttle is open.
MAP Sensor or manifold absolute pressure sensor,
tells the ECM about the engine
vacuum. Simplified, a high vacuum signal means less fuel, the throttle
isn't opened,
a
low vacuum signal means throttle has been opened, more
fuel. Notice I mentioned
about throttle position. The MAP sensor works in conjunction with the
TPS to kind
of create a digital vacuum signal that would be found at
the engine side of a carburetor
slide or butterfly plate. The MAP sensor is also used for ignition
advance. Low vacuum
signal would mean retard the ignition and high vacuum signal would be
advance the
ignition. On carburetted engines the MAP sensor is used only for
ignition
timing.
Temperature Sensor is exactly that. Tells the ECM
the tempature of the engine.
When it senses a cold engine more fuel is added to act like a choke
would on a
carburetor. The idle speed is also raised, just like the fast idle cam
on a choke.
Oxygen Sensor tells the ECM how rich or lean the
exhaust gasses are by sensing
the amount of oxygen in the exhaust gas
stream. When an O2 sensor is used in
a fuel injection system, the
system is known as a "closed loop system" as opposed
to an "open loop
system", which doesn't use O2 sensors for fine tuning fuel
adjustments.
Ok... MOST of the time anyway. Seems the good folks at H-D
have
ruined that one. What they have done on the 2007 up bikes is use the O2
sensor to
satisfy the EPA only, or at least so it seems. On their system the O2
sensor is
only effective from idle to 1/4 throttle, and then it's back to open
loop el-crapo.
From my guess and since they won't give you a truthful answer, it is
done
so they can sell their race tuner and dyno time. If you think about it,
that is
a really dishonest way to do business, not really the kind of people I
want to do
business with...........
An oxygen sensor will give you a 20% swing in fuel
mixture. That means 10% leaner
to 10% richer from the base line map in the ECM. That means you can
install pipes,
air cleaner and a
small set of cams with out re-mapping the ECM. With an open loop
system every time you
change something, the ECM must be re-mapped. It also means
a less
effective
fuel injection system. O2 sensors also compensate for altitude and
weather changes. If
you want a truley closed loop system I suggest Terminal
Velocity II
Output Devices:
Fuel Pump is pretty self explainatory in that it
pumps fuel to the system. If you need to know anything about the fuel
pump it would be that it has to provide a constant 40lbs
pressure to
the injectors. It needs a clean supply of fuel, so you now know that
there
is a filter to be changed periodically. It is turned on and off by the
ECM.
Fuel Pressure Regulator is a mechanical device to
regulate the fuel pressure
from
the pump at a steady 40lbs so the injectors can work properly.
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