Pontiac Fiero 1988 Service Manual page 455

6E2-4 DRIVEABILITY A N D EMISSIONS - F U E L INJECTION (TBI)
A L L N E W G E N E R A L M O T O R S V E H I C L E S A R E C E R T I F I E D B Y T H E U N I T E D S T A T E S
E N V I R O N M E N T A L PROTECTION A G E N C Y A S C O N F O R M I N G T O THE R E Q U I R E M E N T S O F THE
R E G U L A T I O N S FOR T H E C O N T R O L OF AIR P O L L U T I O N F R O M N E W M O T O R V E H I C L E S . THIS
CERTIFICATION IS C O N T I N G E N T ON C E R T A I N A D J U S T M E N T S BEING S E T T O F A C T O R Y
S T A N D A R D S . IN M O S T C A S E S , T H E S E A D J U S T M E N T P O I N T S E I T H E R H A V E B E E N
P E R M A N E N T L Y S E A L E D AND/OR M A D E INACCESSIBLE T O PREVENT INDISCRIMINATE OR
ROUTINE A D J U S T M E N T IN THE FIELD. F O R THIS R E A S O N , THE F A C T O R Y P R O C E D U R E FOR
T E M P O R A R I L Y R E M O V I N G P L U G S , C A P S , E T C . , FOR P U R P O S E S O F SERVICING THE P R O D U C T ,
M U S T BE S T R I C T L Y F O L L O W E D A N D , W H E R E V E R P R A C T I C A B L E , R E T U R N E D T O T H E
ORIGINAL INTENT O F T H E DESIGN.
INTRODUCTION
GENERAL DESCRIPTION
This section applies to engines which have a fuel
injector mounted above a throttle body assembly. The
entire assembly is mounted to the intake manifold and
is referred to as "Throttle Body Injection".
These engines have controls to reduce exhaust
emissions, while maintaining good driveability and
fuel economy.
An engine control module (ECM) is the heart of
this control system and has sensors used to provide
information about engine operation and the various
systems it controls. Details of basic operation,
diagnosis, functional checks, and on-vehicle service
are covered in Section "C", Component Systems.
The ECM has the ability to do some diagnosis of
itself, and of other parts of the system. When it finds a
problem, it lights a "Service Engine Soon" light on the
instrument panel and a trouble code will be stored in
the ECM memory. This does not mean that the engine
should be stopped right away, but that the cause of the
light coming on should be checked as soon as
reasonably possible.
DIAGNOSIS PROCEDURE
The following sections(s) are written for specific
engine applications and are clearly indentified. Be
sure to use only the section which applies to the
engine family being diagnosed.
Before using this section of the manual, you
should be familiar with the information and the
proper diagnosing procedures as described in Section
"6E". If the proper diagnosis procedures are not
followed, as described in Section "6E", it may result in
unnecessary replacement of good parts.
Trouble tree charts incorporate diagnosis
procedures using an ALDL "Scan" tool, where
possible. The "Scan" tool has the ability to save time
in diagnosis and prevent the replacement of good
parts. The key to using the "Scan" tool
successfully for diagnosis lies in the technician's
ability to understand the system he is trying to
diagnose, as well as an understanding of the
"Scan" tool's limitations. See Section 6E for more
information.