03-14-2
Engine Controls, Electronic
03-1 4-2
DESCRIPTION AND OPERATION (Continued)
Powertrain Control Module (PCM)
An on-board vehicle powertrain control module
(PCM)( 1 2A650) performs the following functions:
•
accepts information from various engine sensors to
compute the required fuel flow rate necessary to
maintain a prescribed air /fuel ratio throughout the
entire engine operational range.
•
sends out a command to the fuel injectors to meter
the appropriate quantity of fuel.
•
determines and compensates for the age of the
vehicle and its uniqueness.
•
automatically senses and compensates for changes
in altitude (for example, from sea level to
mountains).
Powertraln Control Module (PCM)
V9929-A
Throttle Position (TP) Sensor
The throttle position sensor (TP sensor)(98989) is:
•
a potentiometer that provides a signal to the
powertrain control module (PCM)( 1 2A650) that is
directly proportional to the throttle plate position.
•
mounted to the throttle body (9E926) and is
connected to the throttle plate shaft.
Throttle Position Sensor
-
3.8L Engine
THROTTLE POSITION SENSOR
98989
THROTTLE BODY
9E926
V10125-A
Throttle Position Sensor
-
4.6L Engine
�
FRONT OF ENGINE
�
THROTTLE POSITION
SENSOR 98989
V10120-A
Mass Air Flow (MAF) Sensor
The mass air flow sensor (MAF sensor)( 1 28579):
•
is located between the air cleaner element (ACL
element)(960
1)
and the air cleaner outlet tube
(98659).
•
uses a hot wire sensing element to measure the
amount of air entering the engine. Air passing over
the hot wire causes it to cool.
•
sends out an analog voltage signal to
the
PCM
( 1 2A650) to determine
the
intake air mass. The
PCM wiU then calculate the required fuel injector
pulse width in order to provide
the
desired air /fuel
ratio.
•
hot wire sensing element and housing are calibrated
as a unit and must be serviced as a complete
assembly.
1997
Thunderbird, Cougar July
1 996