Pontiac Fiero 1988 Service Manual page 437

6 E - 1 0 DRIVEABILITY AND EMISSIONS - FUEL INJECTION
CCP (Carbon Canister Purge)
This displays "ON" when the canister purge
solenoid is commanding purge. Some display duty
cycle from 0-100%.
2nd Gear
This displays the state of the 2nd gear switch.
Yes = 2nd gear applied. It remains applied in 3rd and
4th gears.
3rd Gear
This displays the state of the 3rd gear switch.
Yes = 3rd gear applied. It remains applied in 4th gear.
4th Gear
This displays the state of the 4th gear switch.
Yes = 4th gear applied.
Fan Request
State of the A/C fan control switch is displayed. It
should read "yes" when fan is requested. Some
engines may display the state of the 2nd fan, if used.
Power Steering Pressure Switch
This reading displays the state of switch, and may
vary with the tool used, and the type of switch
installed on the vehicle. The important thing is that
the reading changes state (switches) when the
rteering is moved against the stops.
SECTION B - DRIVEABILITY SYMPTOMS
Always start with Section "A" "Diagnostic Circuit
Check" before proceeding to the driveability
symptoms or an emissions test failure. Section "A"
checks the ECM, which may cause the driveability
problem. A definition of each symptom is included.
This will then lead to the most probable causes of the
driveability problem.
SECTION C - COMPONENT SYSTEMS
There are many component systems that are used
to control fuel and emissions. Section "C" introduces
each component system or control with a general
description, diagnosis, and on-vehicle service.
Each of the Section "C" diagnosis sections contain
information on how the "Scan" tool can be used for
diagnosing a particular component when a trouble
code has not been set. (example: Section "Cl" under
diagnosis will explain how the "Scan" tool can be used
for diagnosis as well as what the normal readings
would be for the ECM sensors.)
Electronic Control Module (ECM)
This section describes the ECM and the
information sensors in the system. Figure 4 shows
the operating conditions which the ECM may sense
and the systems that the ECM may control. (See
specific engines to determine which are applicable to
that engine.)
Fuel Control System
The ECM controls the air/fuel delivery to the
combustion chamber by controlling the fuel flow
through the injector(s).
Electric Fuel Pump (In-tank)
The in-tank fuel pump is controlled by the ECM.
When ignition is turned "ON", the pump will run for 2
seconds, then stop unless the ECM is receiving
ignition pulses, as when cranking or running.
Evaporative Emission Control
This system has a canister which stores fuel vapor
from the fuel tank. The fuel vapor is removed from the
canister and consumed in the normal combustion
process when the engine is running. This system is
used on all engines and may or may not be controlled
by the ECM.
Electronic Spark Timing (EST)
This system is controlled by the ECM, which
controls spark advance (timing), and is used on all
engines.
Electronic Spark Control (ESC)
This system uses a knock sensor in connection
with the ECM to control spark timing, to allow the
engine to have maximum spark advance without
spark knock. This improves driveability and fuel
economy, but will retard spark if detonation (spark
knock) is detected.
Air Injection Reaction (A.I.R.)
The system provides additional oxygen to the
exhaust gases to continue the combustion process.
The system also supplies additional air to the catalytic
converter under certain conditions. The A.I.R. system
is not on all engines.
Early Fuel Evaporation (EFE)
The EFE system heats the engine induction
system electrically or with exhaust gas during cold