Pontiac Fiero 1988 Service Manual page 430

DRIVEABILITY AND EMISSIONS - FUEL INJECTION
6E-3
VEHICLE EMISSION CONTROL INFORMATION
LABEL
The Vehicle Emission Control Information label
(Figure 1) contains important emission specifications
and setting procedures. In the upper left corner is
exhaust emission information which identifies the
year, the manufacturing division of the engine, the
displacement in liters of the engine, the class of
vehicle and type of fuel metering. Also there is an
illustrated emission component and vacuum hose
schematic. A similar label is located in the engine
compartment of every General Motors Corporation
vehicle. If the label has been removed, it can be
ordered from the parts division. (WDDGM)
INTRODUCTION
Electronic Engine Control
Each engine has an electronic engine control
module (ECM) to control the fuel system. The ECM
varies the air/fuel ratio by controlling the fuel flow
through the injector(s).
In addition, the ECM controls the ignition timing
as well as the fuel pump and other systems.
It is important to review the component sections
and wiring diagrams in Section "6E2" and "6E3" for a
specific engine, to determine what is controlled by the
ECM and what systems are non-ECM controlled.
What This Section Contains
Each General Motors engine has system controls
to reduce exhaust emissions while maintaining good
driveability and fuel economy. This section explains:
• How to use the Driveability and Emission
Sections "6E2" for TBI, and
f,
6E3" for Port
Fuel engines.
• A brief description of systems used to control
fuel and emissions.
• Abbreviations that are used in "Driveability
and Emissions".
• Wiring harness service information for
harnesses used with the ECM.
• Special tools used to diagnosis and repair a
system.
Before checking the system, observe the following:
Blocking Drive Wheels
The vehicle drive wheels always should be
blocked, and parking brake firmly set, while checking
the system.
Cold Oxygen Sensor
On some engines, the oxygen sensor will cool off
after only a short period of operation at idle. This will
put the system into "Open Loop". To restore "Closed
Loop" operation, run the engine at part throttle and
accelerate from idle to part throttle a few times until
the system goes "Closed Loop".
VISUAL/PHYSICAL UNDERHOOD
INSPECTION
One of the most important checks that must
be done as part of any diagnostic procedures or
finding the cause of. an emissions test failure is a
careful visual/physical underhood inspection.
This can often lead to fixing a problem without further
steps. Inspect all vacuum hoses for correct routing,
pinches, cuts, or disconnects. Be sure to inspect hoses
that are difficult to see beneath the air cleaner,
compressor, generator, etc. Inspect all the wires in the
engine compartment for correct and good connections,
burned or chafed spots, pinched wires, or contact with
shajp edges or hot exhaust manifolds. This
visual/physical inspection is very important. It must
be done carefully and thoroughly.
BASIC KNOWLEDGE REQUIRED
Before using this section of the service manual,
there are some areas that you should be familiar with.
Without this basic knowledge, you will have trouble
using the diagnostic procedures contained in this
section.
Basic Electric Circuits
You should understand the basic theory of
electricity, and know the meaning of voltage, amps,
ALL NEW G E N E R A L M O T O R S V E H I C L E S A R E CERTIFIED BY THE UNITED S T A T E S
ENVIRONMENTAL PROTECTION AGENCY AS CONFORMING TO THE REQUIREMENTS OF THE
REGULATIONS FOR THE CONTROL OF AIR POLLUTION FROM NEW MOTOR VEHICLES. THIS
CERTIFICATION IS CONTINGENT ON CERTAIN ADJUSTMENTS BEING SET TO FACTORY
STANDARDS. IN MOST C A S E S , THESE ADJUSTMENT POINTS EITHER HAVE BEEN
PERMANENTLY SEALED AND/OR MADE INACCESSIBLE TO PREVENT INDISCRIMINATE OR
ROUTINE ADJUSTMENT IN THE FIELD. FOR THIS REASON, THE FACTORY PROCEDURE FOR
TEMPORARILY REMOVING PLUGS, CAPS, E T C , FOR PURPOSES OF SERVICING THE PRODUCT,
MUST BE STRICTLY FOLLOWED AND, WHEREVER PRACTICABLE, RETURNED TO THE
ORIGINAL INTENT OF THE DESIGN.