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OBD II Scan Tool
©2002 Actron Manufacturing Co.
Printed in USA
ACTRON MANUFACTURING CO.
15825 Industrial Parkway
Cleveland, Ohio 44135-9946
Internet and e-mail - http://www.actron.com
SFI or SEFI:
Sequential Fuel Injection or Sequential Electronic Fuel Injection. A fuel injection system
that uses one or more injectors for each cylinder. The injectors are mounted in the
intake manifold and are fired individually.
Short Term fuel trim.
Throttle Body Injection. A fuel injection system having one or more injectors mounted in a
centrally located throttle body, as opposed to positioning the injectors close to an intake
valve port. TBI is also called Central Fuel Injection (CFI) in some vehicles.
Top Dead Center. When a piston is at its uppermost position in the cylinder.
A device which performs the same function as a carburetor in a fuel injection system. On a
throttle body injection (TBI) system, the throttle body is both the air door and the location of
the fuel injectors. On port fuel injection systems (PFI, MPFI, SFI, etc.), the throttle body is
simply an air door. Fuel is not added until the injectors at each intake port are activated. In
each case, the throttle body is attached to the accelerator pedal.
Throttle Position Sensor. Potentiometer-type sensor connected to the throttle shaft. Its voltage
signal output increases as the throttle is opened. The PCM uses this signal to control many
systems such as idle speed, spark advance, fuel delivery, etc.
Transmission Temperature Sensor. A resistance sensor mounted in the transmission
housing in contact with the transmission fluid. It sends a voltage signal to the PCM indicating
the temperature of the transmission.
Vehicle Emission Control Information. A decal located in the engine compartment containing
information about the emission control systems found on the vehicle. The VECI is the
authoritative source for determining whether a vehicle is OBD II-compliant.
Vehicle Identification Number. This is the factory-assigned vehicle serial number. This
number is stamped on a number of locations throughout the vehicle, but the most prominent
location is on top of the dashboard on the drivers side, visible from outside the car. The VIN
includes information about the car, including where it was built, body and engine codes,
options, and a sequential build number.
Vehicle Speed Sensor. Sends a frequency signal to the PCM. The frequency increases as
the vehicle moves faster to give the PCM vehicle speed information used to determine shift
points, engine load, and cruise control functions.
Wide-Open Throttle. The vehicle operating condition brought about when the throttle is
completely (or nearly) open. The PCM will typically deliver extra fuel to the engine and de-
energize the A/C compressor at this time for acceleration purposes. The PCM uses a
switch or the Throttle Position Sensor to identify the WOT condition.