1988 PONTIAC FIERO key battery

6E2-A-114 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
CHART A-3
(Page I of 2)
ENGINE CRANKS BUT WILL NQ"TRUN
5.OL (VIM E) "F"" SERlES (TBI)
Circuit Description:
This chart assumes that battery condition and engine cranking speed are OK, and there is adequate fuel in
the tank.
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
1. A "Service Engine Soon" light "ON" is a basic test
to determine if there is a 12 volt supply and
ignition 12 volts to ECM. No
ALIII, may be due to
an ECM problem and CHART A-2 will diagnose
the ECM. If TPS is over 2.5 volts, the engine may
be in the clear flood mode, which will cause
starting problems.
2. No spark may be caused by one of several
components related to the ignition system.
CHART
C-4 will address all problems related to
the causes of a no spark condition.
3. Fuel spray from the injector(s) indicates that fuel
is available. However, the engine could be
severely flooded due to too much fuel.
4. While cranking engine, there should be no
f~lel
spray with injector disconnected. Replace an
injector if it sprays fuel or drips like a leaking
water faucet.
5, The fuel pressure will drop after the fuel pump
stops running due to
a controlled bleed in the fuel
system. Use
of the fuel pressure gage will determine
if fuel
system pressure is enough for the engine to start
and run. The key may have to be cycled
2 or more
times for accurate reading.
6. No fuel spray from injector indicates a faulty fuel
system or no ECM control of injector.
7. This test will determine if the ignition module is
not generating the reference pulse if the wiring or
ECM is at fault. By touching and removing
a test
light to 12 volts on CKT 430,
a reference pulse
should be generated. If
injector test light blinks,
the ECM and wiring are
OK.
Diagnost Aids:
@ Water or foreign material can cause a no start
during freezing weather.
@ An EGR sticking open can cause a low airlfuel
ratio during cranking.
@ Fuel pressure: Low fuel pressure can result in
a very lean airlfuel ratio. See CHART A-7.
@ A grounded CKT 423 (EST) may cause a "No-
Start" or a "Start then Stall" condition.

6EZ-Pa-18 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
FUEL PUMP
RELAY CONN.
465 DK GRNMIHT
450 BLWHT
FUEL PUMP
BATTERY JUNCTION TEST TERM. BULKHEAD BODY CONNECTOR
BLOCK
(1 2 VOLT) CONNECTOR
CHART A-7
(Page 1 of 2)
FUEL SYSTEM DlAGNOSlS
5.0L (VIN E) "F"" SERIES (TBI)
Circuit Description:
When the ignition switch is turned "ON", the electronic control module (ECM) will turn "ON" the in-tank
fuel pump. It will remain "ON"
as long as the engine is cranking or running, and the ECM is receiving ignition
reference pulses.
If there are no reference pulses, the ECM will shut
"OI'F" the fuel pump within 2 seconds after key "ON".
The pump will deliver fuel to the THI unit, where the system pressure is controlled to 62 to 90 kPa (9 to 13
psi). Excess fuel is then returned to the fuel tank.
The fuel pump test terminal is located in the left side of the engine compartment. When the engine is
stopped, the pump can be turned "ON" by applying battery voltage to the test terminal.
lest Description: Numbers below refer to circled Diagnostic Aids:
numbers on the diagnostic chart
1. Fuel pressure should be noted while fuel pump is Improper fuel system pressure can result in one of
running. Fuel pressure will drop immediately the following symptoms:
after fuel pump stops running due to a controlled
e Cranks, but won't run.
bleed in the fuel system.
@ Code 44.
@ Code 45.
@ Cuts out, may feel like ignition problem.
@ Poor fuel economy, loss of power.
FIesitation.

6E2-A-54 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
465 DK GRNMlHT
450 BLWHT
FUEL PUMP BATTERY JUNCTION TEST TERM. BULKHEAD BODY CONNECTOR
BLOCK (12 VOLT) CONNECTOR
CODE 54
FUEL PUMP CIRCUIT
(LOW VOLTAGE)
5.OL (VIN E) "F"" SERIES (TBI)
Circuit Description:
When the ignition switch is turned "ON", the electronic control module (ECM) will activate the fuel pump
relay and run the in-tank fuel pump. The fuel pump will operate as long as the engine is cranking or running,
and the ECM is receiving ignition reference pulses.
If there are no reference pulses, the ECM will shut
"OFF" the fuel pump within 2 seconds after key "ON".
Should the fuel pump relay, or the
12 volt relay drive from the ECM fail, the fuel pump will be run through
an oil pressure switch back-up circuit.
Code
54 will set if the ECM does not see the 12 volts signal at terminal "B2" during the 2 seconds that the
ECM is energizing the fuel pump relay.
Diagnostic Aids:
An inoperative fuel pump relay can result in long
cranking times, particularly if the engine is cold or
engine oil pressure is low. The extended crank period
is caused by the time necessary for oil pressure to
build enough to close the oil pressure switch and turn
"ON" the fuel pump.

DRIVEABILITY AND EMISSIONS 5.OL (VIN E) 6EZ-C1-7
BRACKET
INSTRUMENT PANEL
(INSTRUMENT PANEL) '
MODULE ASM ECM (TBI)
BRACKET
1 BOLTISCREW (5) - 1 NUT (4) 4.7-7.0 N.rn (3.3-5.1 LBS. FT.)
NUT
BOLTISCREW (2) 2.2-3.4 N,rn (1.6-2.5 LBS. FT.)
Figure C1-9 - ECM Mounting
NOTICE: To prevent internal ECM damage, the
ignition must be
"OFF" when
disconnecting or reconnecting power to
ECM (for example, battery cable, ECM
pigtail, ECM fuse, jumper cables,
etc.).
Remove or Disconnect
1. Negative battery cable.
2. Right hand hush panel.
3. Connectors to ECM.
4. ECM.
5. PROM from ECM.
Install or Connect
1. OldPROMinnewECM.
2. ECM into car.
3. Connectors.
4. Hush panel.
5. Negative battery cable.
PROM
Code 51 indicates a faulty PROM, bent pins, or
incorrect installation.
ECM HARNESS
PROM CARRIER CONNECTORS TO ECM
1 PROM ACCESS COVER 45 0463-6E
Figure C1-10 PROM Access Cover
1 PROM REMOVAL TOOL 45 0464-6E
Figure C1-I 1 PROM Removal Tool
Important
It is possible to install a PROM backward. If the
PROM is installed backward and the ignition key
turned to "ON," the PROM circuitry will bc
destroyed, requiring PROM replacement.
lmportant
The ignition should always be off wh~n installing
or removing the ECM connectors.
Remove or Disconnect
1. Connectors from ECM.
2. ECM mounting hardware.
3. ECM from passenger compartment.
4. Prom access cover (see Figure C 1- 10)
5, Remove PROM assembly

DRIVEABILIW AND EMISSIONS - 5.OL (VIN E) 6E2-62-1
SECTION C2
FUEL CONTROL SYSTEM
TBI MODEL 228
CONTENTS
GENERAL DESCRIPTION . . . . . . . . . . . . . . . C2-1
PURPOSE ......................... C2-1
MODES OF OPERATION . . . . . . . . . . . . . . C2-1
Starting Mode . . . . . . . . . . . . . . . . . . . C2-1
Clear Flood Mode . . . . . . . . . . . . . . . . C2-2
RunMode . . . . . . . . . . . . . . . . . . . . . . C2-2
Open Loop . . . . . . . . . . . . . . . . . . . . . . C2-2
Closed Loop . . . . . . . . . . . . . . . . . . . . . C2-2
Acceleration Mode . . . . . . . . . . . . . . . C2-2
Deceleration Mode . . . . . . . . . . . . . . . C2-2
Battery Correction Mode . . . . . . . . . . . C2-2
Fuel Cut Off Mode . . . . . . . . . . . . . . . . C2-2
FUEL CONTROL SYSTEM COMPONENTS
. . . C2-2
BASIC SYSTEM OPERATION . . . . . . . . . . . C2-3
THROTTLE BODY INJECTION (TBI) UNIT. . . C2-3
Fuel Injectors . . . . . . . . . . . . . . . . . . . . C2-3
Pressure Regulator . . . . . . . . . . . . . . . C2-3
ldle Air Control (IAC) Valve . . . . . . . . . . C2-4
Throttle Position Sensor (TPS) . . . . . . . . C2-4
FUEL PUMP.. . . . . . . . . . . . . . . . . . . . . . . C2-5
FUEL PUMP ELECTRICAL CIRCUIT . . . . . . . C2-5
DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . * C2-5
FUEL CONTROL . . . . . . . . . . . . . . . . . . . . C2-5
GENERAL DESCRIPTION
PURPOSE
The basic function of the fuel control system is to
control fuel delivery to the engine. Fuel is delivered to
the engine by
a throttle body injection ('FBI) unit.
ENGINE CONTROL MODULE (ECM)
EXHAUST OXYGEN (0,) SENSOR
I 1 THROTTLE BODY INJECTION UNIT (TBI)
CATALYTIC CONVERTER
8P 0352 SYE a 3 81
Figure C2-1 - Closed Loop System
ldle Air Control Valve (IAC) . . . . . . . . . C2-5
Driveability . . . . . . . . . . . . . . . . . . . .. C2-5
ON VEHICLE SERVICE
. . . . . . . . . . . . . . . . . C2-5
GENERAL SERVICE INFORMATION . . . . . . C2-5
Fuel Pressure Relief . . . . . . . . . . . . . . . C2-7
Fuel System Pressure Test . . . . . . . . . . . C2-7
Cleaning and Inspection . . . . . . . . . . . C2-7
Thread Locking Compound . . . . . . . . . C2-7
FUEL METER COVER ASSEMBLY . . . . . . . . C2-7
FUEL INJECTOR ASSEMBLIES . . . . . . . . . . C2-8
FUEL METER BODY ASSEMBLY . . . . . . . . . C2-9
THROTTLE POSITION SENSOR (TPS) . . . . . C2-10
IDLE AIR CONTROL (IAC) VALVE . . . . . . . . C2-11
THROTTLEBODYASSEMBLY .......... C2-11
MINIMUM IDLE SPEED CHECK.. . . . . . . . . C2-12
THROTTLE BODY INJECTION (TBI) UNIT.. . C2-I3
FUEL HOSEIPIPE ASSEMBLIES . . . . . . . . . . C2-13
Materials . . . . . . . . . . . . . . . . . . . . . . C2-13
Fuel Line Repair . . . . . . . . . . . . . . . . . . C2-13
FUEL PUMP RELAY . . . . . . . . . . . . . . . . . . C2-13
OIL PRESSURE SWITCH . . . . . . . . . . . . . . . C2-13
PARTS INFORMATION
. . . . . . . . . . . . . . . . . C2-14
The main control sensor is the oxygen (02) sensor,
which is located in the exhaust manifold. The
O?
sensor tells
the engine control module ECM the
amount of osygen in the exhttust gas, and the ECM
changes the airtfuel ratio to the engine by controlling
the fuel injector.
A 14.7: 1 aidfuel ratio is required for
efficient catalytic converter operation. Because of the
constant measuring and adjusting of the
airlfuel ratio,
the fuel injection system is called a "Closed
IAoopP
System (Figure C2 -1).
MODES OF OPERATION
The ECM monitors voltages from several sensors
to determine how
much fuel to give the engine. The
fuel is delivered under one of several conditions, called
"modes." All the modes are controlled by the ECM.
Starting Mode
When the key is first turned "ON", the ECM turns
on the fuel pump relay for two seconds,
i~nd the l'uel
pump builds up pressure to the TRI unit. The ECM
checks the coolant
temperature sensor, throttle
position sensor
('UPS), manifold absolute pressure
(MAP) sensor, and crank signal, then determines the
proper airtfuel ratio tbr starting. This ranges from

DRIVEABILITY AND EMISSIONS - 5.OL (\/IN El 6EZ-CZ-5
sent to the ECM. The ECM then increases the injector
base pulse width, permitting increased fuel flow.
As the throttle valve rotates in response to
movement of the accelerator pedal, the throttle shaft
transfers this rotational movement to the
'I'PS. A
potentiometer (variable resistor) within the TPS
assembly changes its resistance (and voltage drop) in
proportion to throttle movement.
By applying a reference voltage (5.0 volts) to the
TPS input, a varying voltage (reflecting throttle
position) is available at the TPS output. For example,
approximately 2.5 volts results from a 50% throttle
valve opening (depending on TPS calibration). The
voltage output from the TPS assembly is routed to the
ECM for use in determining throttle position.
FUEL PUMP
The fuel pump is a turbine type, low pressure
electric pump, mounted in the fuel tank. Fuel
is
pumped at a positive pressure (above 62
kPa or 9 psi)
from the fuel pump through the in-line filter to the
pressure regulator in the TBI assembly Excess
fuel is
returned to the fuel tank through the fuel return line.
The fuel pump is attached to the fuel gage sender
assembly. A fuel strainer is attached to the fuel pump
inlet line and prevents dirt particles from entering the
fuel line and tends to separate
water from the fuel
Vapor lock problems are reduced when using an
electric
pump because the fuel is pushed from the tank
under pressure rather than being pulled
under
vacuum, a condition that produces vapor.
An inoperative fuel pump would cause
a. no start
condition. A fuel pump which does not provide enough
pressure can result in poor performance. (See "Fuel
System Pressure Test" procedure).
FUEL PUMP ELECTRICAL CIRCUIT
When the key is first turned "ON" without the
engine running, the ECM turns the
Fuel pump relay
"ON" for two seconds. This builds
up the fuel pressure
quickly. If the engine is not started within two
seconds, the
ECM shuts the fuel pump "OFF" and
waits until the engine starts. As soon as the engine is
cranked, the ECM turns the relay
"ON" and runs the
fuel pump.
As a backup system to the fuel pump relay, the
fuel pump can also be turned on
by the oil pressure
switch. The oil pressure sender has two circuits
internally. One operates the oil pressure indicator or
gage in the instrument cluster,
itnd the other is
anormally open switch which closes when oil pressure
reaches about 28
kPa (4 psi). If the fuel pump relay
fails, the oil pressure switch will run the fuel pump. An
inoperative fuel pump relay can result in long
cranking times, particularly if the engine is cold. The
oil pressure switch will turn on the fuel pump as soon
as oil pressure
reaches about 28 kPa (4 psi).
FUEL CONTROL
Always start with the "Diagnostic Circuit Check"
in Section
"6E2-A". This will reduce diagnosis time
and prevents unnecessary replacement of parts. The
information in this check will direct diagnosis
concerning "Engine
Crunlis But Won't Run" and the
"Fuel Control System," Section
"6E2-C2", including
diagnosis of an injector, pressure regulator,
fuel pump,
fuel
pump relay, and oil pressure switch.
Idle Air Control (IAC) Valve
A "Scan" tool reads IAC position in steps, calletl
"Counts." "0" steps indicates the ECM is commanding
the
IAC to be driven in, to a fully seiltetl position
(minimum idle air).
The higher the number steps, the
more idle air being allowed to pass
by the IAC valve.
cnose Refer to CHART C-2C for information to cliil,
the function of the IAC valve.
Driva bility
Refer to Section "B" for driveability symptoms
related to the fuel control.
ON-VEHICLE SERVICE
GENERAL SEWVICE INFORMATION
CAUTION:
e To prevent personal injury or damage to the
vehicle
as the result sf an accidental start,
disconnect and reconnect the negative
battery cable before and after service is
performed.
@ Also, catch any fuel that leaks out when
disconnecting the fuel lines, by covering the
fittings with
a shop cloth. Place the cloth in
an approved container when work is
complete.
The 'FBI unit repair procedures cover component
replacement with the unit on the vehicle,
tIowever,
throttle body replacement requires that the complete
unit
be removed from the enginc.

6E3-C1-6 2.8L (VIM O) DRlVEABlLlTY AND EMISSIONS
amportant
When replacing the production ECM with a
service ECM (controller), it is important to
transfer the Broadcast code and production
ECM number to the service ECM label. Please
do not record on ECM cover. This will allow
positive identification of ECM parts
throughout the service life of the vehicle.
amportant
To prevent internal ECM damage, the ignition
must be "OFF" when disconnecting or
reconnecting power to ECM (for example,
battery cable, ECM pigtail, ECM fuse, jumper
cables,
etc.).
ECM AND COMPONENTS REPLACEMENT
PROM OR ECM
Code 51 indicates a faulty PROM, possibly caused
by bent pins, or incorrect installation.
mmportant
It is possible to install a PROM backwards. If the
PROM
is installed backwards and the ignition key
turned to "ON," the PROM circuitry will be destroyed,
requiring PROM replacement.
NOTICE: The ignition should always be off when
installing or removing the ECM
connectors or internal components.
memove or Disconnect
1. Negative battery cable.
2. Right hand hush panel.
3. Connectors from ECM.
4. ECM mounting hardware.
5. ECM from passenger compartment.
6. ECM access cover (see Figure
C1-6).
7. Remove PROM assembly.
amportant
Using the rocker-type PROM removal tool,
enga& one end of t-hk PROM carrier with the
hook end of the tool (see Figure
C1-8). Press on
the vertical bar end of the tool and rock the
engaged end of the PROM carrier up as far as
possible. Engage the opposite end of the
PROM carrier in the same manner and
rock
this end up as far as possible. Repeat this
process until the PROM carrier and PROM are
free of the PROM socket.
The PROM carrier
with PROM in it Should lift off of the PROM
socket easily. PROM carrier should only
he
removed by using the pictured PROM removal
tool. Other methods could cause damage to the
PROM or PROM socket.
( ECM HARNESS
PROM CARRIER CONNECTORS TO ECM
1 PROM ACCESS COVER
Figure C1-6 PROM Access Cover
PROM CARRIER
PROM REMOVAL TOOL
Figure C1-7 PROM Removal Tool
Hnspect
1. New PROM for same part number as old.
Do not remove PROM from carrier to check PROM
number
2. For correct reference of PROM in carrier, Figure
C1-8.
3. CALPAK Assembly
Using the removal tool, pictured in Figure C1-9,
grasp the carrier
at the narrow ends. Gently rock the
carrier
from end to end while applying a firm upward
force and remove the CALPAK and carrier. Use of
unapproved
CAL,PAK removal tools or methods will
cause
damage to the CAI,PAK or CALPAK socket.

DRIVEABILITY AND EMISSIONS - FUEL INJECTION 6E-5
TERMINAL IDENTIFICATION
GROUND SERIALDATA
(SEE SPECIAL TOOLS)
DIAGNOSTIC TERMINAL
I.I.R. (IF USED) T.C.C. (IF USED)
SERVICE
ENGINE FUEL PUMP (IF USED)
SOON LAMP- IF USED
SERIAL DATA (IF USED) 3-29-86 *6S 2615-6E (SEE SPECIAL TOOLS)
Figure 2 - ALDL Connector
are stored, Code 12 will continue to flash until the
Diagnostic terminal is ungrounded.
Codes can only be obtained with the engine
stopped. Grounding the Diagnostic terminal with the
engine running gives the "field service mode".
2. Display any stored trouble codes by flashing the
"Service Engine Soon" light. Each code will be
flashed three times, then Code
12 will be flashed
again.
If a trouble code is displayed, the memory is
cleared, then the engine is run to see
if the code is
a "hard" or "intermittent" failure. If it is a "hard"
failure, a Diagnostic Code chart is used to find the
problem. If it is an intermittent failure, the charts
are not used. Diagnostic aids are usually included
on the facing page. Section
"B" also covers the
topic of "Intermittents".
A physical inspection of
the applicable system most often will resolve the
problem.
3. Energize all ECM controlled relays and solenoids
except fuel pump relay
.
4. The IAC valve on most models also moves to the
fully extended position.
Field Service Mode
If the Diagnostic terminal is grounded with the
engine running, the system will enter the Field
Service mode. In this mode, the "Service Engine
Soon" light will show whether the system is in "Open"
or
"Closed Loop".
In "Open Loop" the "Service Engine Soon" light
flashes two and one-half times per second.
In "Closed Loop", the light flashes once per second:
Also, in "Closed Loop", the light will stay OUT most of
the time
if the system is too lean. It will stay "ON"
most of the time if the system is too rich.
While the system is in Field Service Mode, the
ECM will be in the following mode:
1. New trouble codes cannot be stored in the ECM.
2. The "Closed Loop" timer is bypassed.
Clearing Trouble Codes
When the ECM sets a trouble code, the "Service
Engine Soon" light will come "ON" and a trouble code
will be stored in memory. If the problem is
intermittent, the light will go out
10 seconds after the
fault goes away. However, the trouble code will stay
in the ECM memory until the battery voltage to the
ECM is removed. Removing battery voltage for
30
seconds will clear all stored trouble codes.
Trouble Codes should be cleared after repairs have
been completed. Also, some diagnostic charts will tell
you to clear the codes before using the chart. This
allows the ECM to set the code while going thru the
chart, which will help to find the cause of the problem
more quickly.
NOTICE: To prevent ECM damage, the key must
be
"OFFn when disconnecting or
reconnecting power to
ECM (for
example battery cable,
ECM pigtail,
ECM fuse, jumper cables, etc.).
ECM Learning Ability
The ECM has a "learning" ability which allows it
to make corrections for minor variations in the fuel
system to improve driveability. If the battery is
disconnected to clear diagnostic codes, or for repair,
the "learning" process has to begin all over again.
A
change may be noted in the vehicle's performance. To
"teach" the vehicle, make sure the engine is at
operating temperature, and drive at part throttle,
with moderate acceleration and idle conditions, until
normal performance returns.
DRIVEABILITY AND EMISSIONS
SECTIONS
6E2 and 6E3 SUMMARY
The Driveability and Emissions sections are
subdivided into three sub-sections:
SECTION A: STARTING POINT AND CODE CHARTS
@ Diagnostic circuit check (Starting Point)
@ No-start and fuel system check charts
@ Code Charts
SECTION B: SYMPTOMS
e Based on driveability symptoms, when no
codes, or intermittent codes, are stored.
SECTION C: COMPONENT SYSTEMS
@ Circuit descriptions
@ On-car service
@ Functional checWDiagnosis charts