PONTIAC FIERO 1988 Service Repair Manual

6E2-C8-6 DRIVEABILITY AND EMISSIONS - 5.OL (VIN E)
I.P. HARNESS CONNECTOR 15 WAY (FRONT VIEW)
ECM
VEHICLE SPEED SIGNAL
SPEED INPUT
4TH GEAR SIGNAL
422 TANIBLK
ALDL CONNECTOR
* 85 4435-66 6-8-87
CHART C-8A
700-4R TRANSMISSION
ELECTRICAL DIAGNOSIS
(Page 2 of 2)
5.0L (VIN E) "F" "SERIES (TBI)
Circuit Description:
A 4th gear switch (mounted in the trans.) opens when the trans. shifts into 4th gear, and this switch is used
by the ECM to modify TCC lock and unlock points, when in a 4-3 downshift maneuver.
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
1. Unless the switch or CKT 446 is open the "Scan"
should display "NO", indicating the trans. is not
in 4th gear.
The 4th gear switch should only he
open whiie in 4th gear.
2. This step determines if the ECM and wiring are
OK. Grounding CKT 446 should cause the "Scan"
to display "NO", indicating the trans. is not in 4th
gear.
3. Checks the operation of the 4th gear switch.
When the trans. shifts into 4th
geir the switch
should open and the "Scan" should display
"YES".
4. Disconnecting the TCC connector simulates an
open switch to determine if CKT
446 is shorted to
ground or the problem is in the transmission.
Diagnostic Aids:
A road test may be necessary to verify the
customer complaint. If the "Scan" indicates TCC is
turning
"ON" and "OFF" erratically, check the state
of the 4th gear switch to he sure it is not changing
states under a steady throttle position.
If the switch is
changing states, check connections and wire routing
carefully. Also if the 4th gear switch is always open
the
TCC may engage as soon as sufficient oil pressure
is reached.

DRIVEABILITY AND EMISSIONS - 5.OL (VIN E) 6EZ-C8-7
DISCONNECT TCC ELECTRICAL CONNECTOR.
SHIFT VEHICLE INTO OVERDRIVE

6E2-C8-8 DRIVEABILITY AND EMISSIONS - 5.OL (VIN E)
I.P. HARNESS CONNECTOR
INTRUMENT 15 WAY. (FRONT VIEW)
CHART C-8B
MANUAL "TRANSMISSION (Mn)
SWIFT LIGHXCHCK
5.OL (VIN E) "F" "SERIES ("Ti)
Circuit Description:
The shift indicates the best transmission shift point for maximum fuel economy. Phe light is controlled by
the ECM and is turned "ON" by grounding
CKT 456.
The ECM uses information from the following inputs to control the shift light:
@ Coolant temperature
@ TPS
VSS
@ RPM
The ECM uses the measured rpm and the vehicle speed to calculate what gear the vehicle is in. It is this
calculation that determines when the shift light should be
turned on.
Test Description: Numbers below refer to circled 3. This checks the shift light circuit up to the ECM
numbers on the diagnostic chart. connector.
If the shift light illuminates, then the
1. This should not turn "ON" the shift light. If the ECM
connector is faulty, or the ECM does not
light is "ON", there is
a short to ground in CKT have the ability to ground the circuit.
456 wiring, or a fault in the ECM.
2. When the diagnostic terminal is grounded, the
ECM should ground CKT 456, and the shift light
should come on.

DRIVEABILITY AND EMISSIONS - S.OL (WIN E) 6EZ-CS-9
CHART C-8B
MANUAL TRANSMISSION (Mn)
SHIFT LIGHT CHECK
CM CONNECTORS.
IGNITION "ON" THERMOSTAT FAULTY OR
JUMPER CKT 456 TO GROUND INCORRECT HEAT RANGE.
IF OK, REVIEW SYMPTOMS
CHECK AND REPAIR:
- OPEN IGNITION CKT 39
- OPEN CKT 456

DRIVEABILITY AND EMISSIONS - 5.OL (VIN E) 6E2-CI 3-1 --
SECTION C13
POSI"BVE CRANKCASE VENTILATION (PCV)
CONTENTS
GENERAL DESCRIPTION ............*.. C13-1 ON-CARSERVICE .................... C13-2
DIAGNOSIS
.*.....................* C13-1 PARTSINFORMATION...,............. C13-2
RESULTS OF INCORRECT OPERATION ... C13-1
GENERAL DESCRIPTION
A positive crankcase ventilation (PCV) system is
used to consume crankcase vapors in the combustion
process instead of venting to atmosphere. Fresh air
from the air cleaner is supplied to the crankcase,
mixed with blow-by gases and then
passe2 through a
positive crankcase ventilation
(PCV) valve into the
intake manifold (Figure
C13-2).
The primary control is through the PCV valve
which meters the flow at a rate depending on manifold
vacuum.
CHECKVALVE
a CLEAN AIR
- VOLATILE OIL FUMES
--+ MIXTURE OF AIR AND FUMES
To maintain idle quality, the PCV valve restricts
the flow when intake manifold vacuum is high. If
abnormal operating conditions arise, the system is
TO THROTTLE BODY
designed to allow excessive amounts of blow-by gases CRANKCASE VENT HOSE
to back flow through the crankcase vent tube into the PCV VALVE HOSE
air cleaner to be consumed by normal combustion. TO INTAKE MANIFOLD
@ A leaking valve or hose would cause:
@ Roughidle. Figure C13-2 - PCV-Flow
@ Stalling.
@ High idle speed.
DIAGNOSIS
3. Place your thumb over end of valve to check
for vacuum. If there is no
vacuuin at valve,
check for plugged hoses or manifold port, or
PCV valve. Iteplace plugged or deteriorated
hoses.
If an engine is idling rough, check for a clogged
4. Turn "OFF" the engine and remove PCV PCV valve or plugged hose. Replace as required. Use
valve. Shake valve and listen for the rattle of
the following procedure:
check needle inside the valve. If
valve does not 1. Remove PCV valve from rocker arm cover.
rattle, replace valve.
2. Run the engine at idle.

6E2-C"1-2 DRIVEABILITY AND EMISSIONS - 5.OL (VIN E)
With this system, any blow-by in excess of the
system capacity (from a badly-worn engine, sustained
heavy load,
etc.) is exhausted into the air cleaner and
is drawn into the engine.
Proper operation of the PCV System is dependent
upon a sealed engine. If oil sludging or dilution is
noted, and the PCV System is functioning properly,
check engine for possible cause and correct to ensure
that system will function as intended.
Results of Incorrect PCV Operation
@ A plugged valve or hose may cause:
@ Rough idle.
@ Stalling or slow idle speed.
Oil leaks.
@ Oil in air clcaner.
@ Sludge in engine.
ON-CAR SERVICE
An engine which is operated without any
crankcase ventilation can be damaged. Therefore, it is
important to replace the
PCV valve and air cleaner
breather at intervals shown in Section
"OB".
Periodically, inspect the hoses and clamps and
replace any showing signs of deterioration.
PARTS INFORMATION
PART NAME GROUP
Air Cleaner ......................... 3.402
................ Valve Asm, UCase Vent 1.745

DRIVEABILITY AND EMISSIONS - S.OL (VIN El 6EZ-C44-1
SECTION C14
"FHERMOSTATlC AIR CLEANER (THERMAC)
CONTENTS
GENERAL DESCRIPTION ............... C14-1 VACUUM MOTORCHECK ............. C14-2
PURPOSE ........................ C14-1 TEMPERATURE SENSOR CHECK ........ 614-3
.................... OPERATION ...................... C14-1 ON CAR SERVICE C14-3
DIAGNOSIS ...e..oe........e.ee.~.. C14-2 AIRCLEANER ELEMENT .............. Cl4-3
RESULT OF INCORRECT THERMAC VACUUM
DIAPHRAGM MOTOR ........ 614-3
.................... OPERATION C14-2
SENSOR .......................... 614-3
THERMACAIR CLEANER CHECK ........ C14-2 PARTS INFORMATION ................ C14-4
GENERAL DESCRIPmION
PURPOSE
A heated intake air system is used to give good
driveability under varying climatic conditions. By
having a uniform inlet air temperature, the fuel
system can be calibrated to reduce exhaust emissions
and to eliminate throttle valve icing.
OPERATION
The THERMAC air cleaner operates by heated air
and manifold vacuum (Figure C14-1). Air can enter
the air cleaner from outside the engine compartment
or from a heat stove built around the exhaust
manifold.
A vacuum diaphram motor, built into the
air cleaner snorkel, moves a damper door, to admit hot
air from the exhaust manifold, outside air, or
a
combination of both. Inside the air cleaner is a
temperature sensor that reacts to air intake
temperature and controls the amount of vacuum going
to the motor.
@ Hot Air Delivery Mode. When the temperature is
below
86°F (30°C), the sensor allows vacuum to the
motor and the damper door will be up, shuting off
outside air and allowing only heated air
from the
exhaust manifold to enter the air cleaner.
@ Outside Air Delivery Mode. When the
temperature is above 55°C
(131°F), the damper
door drops down and only outside air enters the air
cleaner.
VACUUM DIAPHRAGM
MOTOR
TEMPERATURE SENSOR
( VACUUM HOSE (TO
MANIFOLD VACUUM)
1 HEAT STOVE DUCT
151 SNORKEL
16( LINKAGE
1 AIR BLEED VALVE
1 AIR CLEANER ASM.
191 DAMPER DOOR 45 0648-6E
~igure C14-1 - THERMACAir Cleaner - Typical
@ . Between 30°C (86°F) and 55°C
(131°F) the damper door allows both heated and
outside air to enter the air cleaner.

6E2-C14-2 DRIVEABILITY AND EMISSIONS - 5.OL (VIN E)
Figure C14-2 Thermac Operation
VACUUM DIAPHRAGM MOTOR
DIAPHRAGM
SPRING
TEMPERATURE SENSOR
a AIR BLEED VALVE-CLOSED - AIR BLEED VALVE- PARTIALLY OPEN
AIR BLEED VALVE-OPEN
VACUUM HOSES
DIAPHRAGM
a HEAT STOVE
HOT
AIR (EXHAUST MANIFOLD)
DAMPER
DOOR
OUTSIDE INLET AIR
11 SNORKEL r"l
A - HOT AIR DELIVERY MODE
B - REGULATING MODE
C
--OUTSIDE AIR DELIVERY MODE
DIAGNOSIS
4.
RESULTS OF INCORRECT
THERMAC OPERAITON
Hesitation during warm-up can be caused by:
r Heat stove tube disconnected. 5.
r Vacuum diaphram motor inoperative (open to
snorkel).
@ No manifold vacuum.
Damper door does not move.
Missing air cleaner to carburetor seal. Start
engine. Watch damper door in air cleaner
snorkel. When engine is first started, damper door
should move and close off outside air.
As air cleaner warms up, damper door should open
slowly to outside air.
If the air cleaner fails to operate as described
above, perform vacuum motor check. If it operates,
the door may not be moving
at the right
temperature. If the driveability
problem is during
warm-up, make the temperature sensor check
below.
- @ Missing air cleaner cover seal or loose cover.
r Loose air cleaner. VACUUM MOTOR CHECK
Spark Knock, Lack of power, sluggish, or spongy, on a
hot engine can be caused by: I. With engine "OFF", disconnect vacuum hose at
@ Damper door does not open to outside air. vacuum
diaphragm motor.
@ Temperature sensor doesn't bleed off vacuum. 2. Apply at least 23 kPa (7in.fIg.) of vacuum to the
vacuum diaphragm motor. Damper door should
THERMAC AIR CLEANER CHECK completely block off to outside air when vacuum is
applied. If not, check to see if linkage is hooked up
. .
1. Inspect system to be sure all hoses and heat stove correctly.
tube are connected. Check for kinked, plugged or 3. With vacllum still applied, trap Vacuum in
deteriorated
hoses. vitcuum diaphragm motor by bending hose.
2. Check for presence and condition of air cleaner to Ilarnper door should remain closed. If not, replace
carburetor gasket seal. vacuum
diaphragm motor assembly. (Failure of
3. With air cleaner assembly installecl, damper door the
vacuum diaphragm motor assembly is more
should be open to outside air.

DRIVEABILITY AND EMISSIONS - 5.OL (VIN E) 6EZ-C14-3
likely to be caused from binding linkage or a
corroded snorkel than from a failed diaphragm.
This should be checked first, before replacing the
diaphragm.)
4. If vacuum motor checks OK, check vacuum hoses
and connections. If OK, replace the temperature
sensor.
TEMPERATURE SENSOR CHECK
1. Start
test with air cleaner temperature below 30°C
(86°F). If engine has been run recently, remove air
cleaner cover and place thermometer as close as
possible to the sensor. Let air cleaner cool until
thermometer reads below 30°C
(86°F) about 5 to 10
minutes. Reinstall air cleaner on engine and
continue to Step
2.
2. Start and idle engine. Damper door should move to
close off outside air immediately if engine is cool
enough. When damper door starts to open the
snorkel passage (in a few minutes), remove air
cleaner cover and read thermometer. It must read
about
55°C (131°F).
3. If
the damper door is not open to outside air at
temperature indicated, temperature sensor is
malfunctioning and must be replaced.
OM-CAR SERVICE
AIR CLEANER ELEMENT
Remove or Disconnect
1. Air cleaner cover.
2. Old element.
Install or Connect
1. New element.
2. Air cleaner
cover. Do not over-torque nuts (install
finger- tight).
i
VACUUM DIAPHRAGM MOTOR
~emove or Disconnect
1. Air cleaner.
2. Vacuum hose from motor.
3. Drill out the two spot welds initially with a 1.
6mm (1116") drill, then enlarge as required to
remove the retaining strap. Do not damage the
snorkel tube.
4. Motor retaining strap.
5. Lift up motor, cocking it to one side to unhook the
motor linkage at the control damper assembly.
MOTOR ASM.
I 1 RETAINING STRAP - I
Figure C14-3 - Replacing THERMAC Vacuum Motor
Install or Connect
1. Drill a 2.8mm (7164") hole in snorkel tube at
center of vacuum motor retaining strap.
2. Vacuum motor linkage into control damper
assembly.
3. Use the motor retaining strap and sheet metal
screw provided in the motor service package to
secure motor to the snorkel tube. Make sure the
screw does not interfere with the operation of the
damper assembly. Shorten screw if required.
4. Vacuum
hose to motor and install air cleaner.
SENSOR
n Remove or Disconnect
1. Air cleaner.
2. Hoses at sensor.
3. Pry
up tabs
on sensor retaining clip. Remove clip
and sensor from air cleaner. Note position
of
sensor for installation.
Install or Connect
1. Sensor and gasket assembly in original position.
2. Retainer clip on hose connectors.
3. Vacuum hoses and air cleaner on engine.