Actron CP9035 Insrucciones página 16

COMPUTER BASICS
based on how far the throttle is opened by the driver. The computer "knows" how
much air can flow through the carburetor at various throttle openings, and adds
the appropriate amount of fuel to the mixture at the carburetor.
Fuel injection is somewhat more sophisticated in the way it delivers fuel. The
computer still adds an appropriate amount of fuel to the entering air, but now it
uses fuel injectors (either in a throttle body or at each intake port). Fuel injectors
are far more precise than carburetor jets, and create a much finer fuel "mist" for
better combustion and increased efficiency. In addition, most electronic fuel
injection systems can measure the mass of the air entering the engine. This
measurement is used in calculating the proper air/fuel ratio using lookup tables.
Computers no longer have to "estimate" how much air the engine is using.
In many modern systems, the computer also uses information provided by
sensors that indicate if the amount of fuel needs to be increased or decreased.
Sensors can tell the computer how warm the engine is, how rich or lean the fuel
mixture is, and whether accessories (like the air conditioner) are running. This
feedback information allows the computer to "fine tune" the air/fuel mixture,
keeping the engine operating at its peak.
What the Computer needs to know:
Engine operating condition. Sensors used are: coolant temperature, throttle
position, manifold pressure (vacuum), air flow and RPM.
Air intake. Sensors used are: mass air flow, manifold absolute pressure,
manifold air temperature and RPM.
Air/fuel mixture status. Sensors used are: oxygen sensor(s).
NOTE: Not all engines use every sensor listed above.
Open and Closed Loop Modes:
Open or closed loop operation refers to the way the computer is deciding how
much fuel to add to the air entering the engine. During cold start and other low
demand, low temperature situations, the computer operates in open loop mode.
This means the computer is relying on a set of internal calculations and data
tables to decide how much fuel to add to the incoming air. It uses sensors such
as the coolant temperature sensor (CTS), the throttle position sensor (TPS), and
the manifold absolute pressure sensor (MAP) to determine optimum mixtures.
The important difference here is that the PCM does not adjust the fuel mixture on
information from exhaust gas sensors.
In closed loop mode, the computer still decides how much fuel to add by using
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