PONTIAC FIERO 1988 Service Repair Manual

6E3-C6-4 5.QL (VIN F) & 5.7L (WIN 8) DRI'JEABILITY AND - .. EMISSIONS
AIR INJECTION CHECK VALVE
a Remove or Disconnect
1 . Release clamp and disconnect air hoses from check
valve
.
2 . Unscrew check valve from air injection pipe .
install or Connect
1 . Screw check valve onto air injection pipe . 23 N-m
(1'7 1h . ft.).
2 . Position air hoses on check valve and secure with
clamp
.
PARTS IMF0RMA"TION
PART NAME GROUP
............. Adapter. AIR Inj Cont Vlv 3.671
Brace. AIR Inj Pump
................. 3.655
Bracket. AIR Inj Pump
............... 3.655
............ GasLet. AIR Inj Dvtr Vlv El 3.671
Haniess. AIR Inj Cont Vlv Vac .......... 3.675
................ Hose. AIR Inj Cont Vlv 3.675
Hose. AIR Inj Cont Vlv Dvtr
........... 3.675
Hose.
Ctltc Conv AIR Inj Chk Vlv ....... 3.675
........ Pipe. AIR Inj Ctltc Conv Chk Vlv 3.690
Pipe. Ctltc Conv AIR Inj
............... 3.675
................. Pulley. AIR Inj Pump 3.650
..................... Pump. AIR Inj 3.660
............. Silencer AIR Inj Cont Vlv 3.660
................ Support.
AIR Inj Pump 3.660
.................. Valve. AIR Inj Cont 3.670
............... Valve. AIR Inj Eng Chk 3.670
......... Valve.
C tltc Conv AIR Inj Chk 3.670
Figure C6-4 . PEDES Valve
Service

DRIVEABILITY AND EMISSIONS 5.OL (WIN F) & 5.7L (VIN 8) 6E3-C6-5
BLANK

6E3-C6-6 5.OL (VIN F) & 5.7L (VIN 8) DRIVEABILITY AND EMISSIONS
AIR MANAGEMENT CHECK (PEDES)
5.OL (VIN F) & 5.7L (VIN 8) "F" SERIES (PORT)
Circuit Description:
Air management is controlled by a pressure operated port valve and a converter valve, each with an ECM
controlled solenoid. When the solenoid is grounded by the ECM, AIR pressure will activate the valve and allow
pump air to be directed as follows:
@ Cold Mode - The port solenoid is energized which in turn opens the port valve and allows flow to the
exhaust ports.
@ Warm Mode - The port solenoid is de-energized and the converter solenoid energized which closes the
port valve and keeps the converter valve seated, thus forcing flow past the converter valve and to the
converter.
@ Divert Mode - Both solenoids are de-energized, which opens the converter valve, allowing air to take the
path of least resistnance,
i.e., out the di~ertl~elief tube to atmosphere.
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
1. This is a system functional check. Air is directed
to ports during "Open Loop" and all engines start
in "Open Loop" even on a warm engine. Since the
air to the ports may be very short, prepare to
observe port air prior to engine start up. This can
be done by squeezing a hose.
2. This should normally set a Code 22. When any
code is set, the ECM opens the ground to the
converter solenoid and allows air to divert. This
checks for ECM response to a fault. A ground in
the control valve circuit to the ECM would prevent
divert action.
3. This checks for a grounded circuit to the ECM.
Test light
"OFF" is normal and would indicate the
circuit is not grounded.
4. Checks for an open in the solenoid control circuits.
Grounding the test terminal should ground both
solenoid circuits. Normally, the test light should
be
"ON", which indicates the problem is not in the
ECM or wiring but at the solenoid connections or
valve itself.
5, Checks for a grounded solenoid circuit. Test light
"OFF" would indicate the circuit is normal and
fault is in the valve.

DRIVEABILITY AND EMISSIONS 5.OL (VIN F) & 5.7L (\/IN 8) 6E3-C6-7

6E3-C6-8 5.OL (VIN F) & 5.7L (VIN 8) DRIVEABILITY AND EMISSIONS
BLANK

DRIVEABILITY AND EMISSIONS 5.0L (VIN F) €4 5.7L (VIN 8) 6E3-C7-1
SECTION C7
EXHAUST GAS REClRCULATlON (EGR) SYSTEM
CONTENTS
................ GENERAL DESCRIPTIlDN C7-1 DIAGNOSIS ........................ C7-2
PURPOSE
......................... C7-1 EGR VALVE ...................... C7-3
....................... OPERATION C7-1 EGR Manifold Passage ............... C7-3
.................... EGR CONTROL C7-1
EGR CONTROL SOLENOID ............ C7-3
NEGATIVE BACKPRESSURE EGR VALVE
. . C7-2 PARTS INFORMATION ................. C7-3
......... EGR VALVE IDENTIFICATION.. C7-2
... RESULTS OF INCORRECT OPERATION C7-2
GENERAL DESCRIPTION
PURPOSE
The EGR system is used to lower NO, (oxides of
nitrogen) emission levels caused by high combustion
temperature. It does this by decreasing combustion
temperature. The main element of the system is the EGR valve
operated by vacuum and mounted on the intake
manifold.
The EGR valve feeds small amounts of exhaust
gas back into the combustion chamber as shown in
Figure
C7-1.
OPERATION
The EGR valve is opened by vacuum to let exhaust
gas flow into the intake manifold. The exhaust gas
then moves with the
airlfuel mixture into the
combustion chamber.
If too much exhaust gas enters,
combustion will not occur. For this reason, very little
exhaust gas is allowed to pass through the valve,
especially at idle. The EGR valve is usually open
during warm engine operation and when the vehicle is
above idle speed. The amount of exhaust gas recirculated is
controlled by variations in vacuum and the
EGR
vacuum control solenoid.
EGR CONTROL
The EGR vacuum control has a vacuum solenoid
that uses "pulse width modulation".
EGR VALVE INTAKE AIR
EXHAUST GAS EGR VACUUM PORT
Figure C7-1 Exhaust Gas Recirculation
This means the ECM turns the solenoid "ON" and
"OFF" many times a second and varies the amount of
"ON" time ("pulse width") to vary the amount of EGR.
A diagnostic switch is part of the control and
monitors vacuum to the EGR valve. This switch will
trigger a "Service Engine Soon" light, and set a Code
32 in the event of a vacuum circuit failure.
During cold operation and at idle, the solenoid
circuit is not grounded by the ECM. This blocks
vacuum to the EGR valve.
Grounding the
ALDL diagnostic "test" terminal,
with the ignition "ON" and the engine not running,
will energize the solenoid and block vacuum to the
EGR valve.

NEGATIVE BACKPRESSURE EGR VALVE
The valve on this engine is called a negative
backpressure valve. It varies the amount of exhaust
gas flow into the manifold depending on manifold
vacuum and variations in exhaust backpressure.
The diaphragm on this valve (shown in Figure
C7-2) has an internal vacuum bleed hole which is held
closed by
a small spring when there is no exhaust
backpressure. The amount of vacuum to the valve is
controlled by the
ECM controlling a solenoid.
Engine vacuum opens the EGR valve against the
pressure of
a large spring. When manifold vacuum
combines with negative exhaust backpressure, the
vacuum bleed hole opens and the EGR valve closes.
EGR VALVE AIR BLEED
EXHAUST GAS HOLE
INTAKE AIR SMALL
SPRING
VACUUM PORT LARGE
SPRING
Figure C7-2 - Negative Backpressure EGR Valve
EGR VALVE IDENTIFICATION
@ Negative backpressure EGR valves will have an
"N" stamped on the top side of the valve after the
part number (Figure
C7-3).
@ Positive backpressure EGR valves will have a "P"
stamped on the top side of the valve, after the part
number.
@ Port EGR valves have no identification stamped
after the part number.
When replacing an
EGIE valve, always check for
correct part number in the parts catalog or
supplemental bulletin.
Figure C7-3 - EGR Valve Identification
RESULTS OF INCORRECT OPERATION
Too much EGR flow tends to weaken combustion,
causing the engine to run roughly or stop. With too
much EGR flow at idle, cruise, or cold operation,
aliy
of the following conditions may happen:
@ Engine stops after cold start.
@ Engine stops at idle after deceleration.
@ Car surges during cruise.
@ Rough idle.
If the EGR valve should stay open all of the time,
the engine may not idle.
Too little or no EGR flow allows combustion
temperatures to get too high during acceleration and
load conditions. This could cause:
@ Spark knock (detonation).
@ Engine overheating.
@ Emission test failure.
DIAGNOSIS
Diagnosis of the EGR system is covered in CHART C-7
at the end of this section.
EGR VALVE
Remove or Disconnect
1. Plenum (See Plenum R&R).
2. Vacuum line.
3. Retaining bolts.
4. EGR valve.
Install or Connect
1. Reinstall valve or replacement EGR valve on
intake manifold using new gasket.
2. Bolts and tighten to 18 N.m (14 Ib. ft.).
3. Vacuum line to valve.
4. I'lenum.

DRIVEABILITY AND EMISSIONS 5.OL (VIN F) & 5.7L (VIN 8) 6E3-C7-3
1. With a wire wheel, buff the exhaust deposits from
the mounting surface and around the valve.
2. Look for exhaust deposits in the valve outlet.
Remove deposit build-up with a screwdriver.
3. Clean mounting surfaces of intake manifold and
valve assembly.
EGR SOLENOID 1 EGR VALVE
121 COIL 151 BOLTS (2)
ls] BOLT (2) 21 N.m EGR DlAG TEMP SWITCH
(16 FT. LBS.) 12 N.m (105
IN. LBS.)
Figure C7-4 - EGR and Solenoid Service
EGR Manifold Passage
Inspect
If EGR passages in the inlet manifold indicate
excessive build-up of deposits, the passages should be
cleaned. Care should be taken to ensure that all loose
particles are completely removed to prevent them
from clogging the EGR valve or from being ingested
into the engine.
Do not wash EGR valve in solvents or degreaser--
permanent damage to valve diaphragm may result.
Also, sand blasting of the valve is not recommended
since this can affect the operation of the valve.
EGR CONTROL SOLENOID
Remove or Disconnect
1. Negative battery cable.
2. Electrical connector at solenoid
3. Vacuum hoses.
4. Nut and solenoid.
Install or Connect
1. Solenoid and bracket, tighten nut to 24 N-m
(17 1b. ft.).
2. Vacuum hoses.
3. Electrical connector.
4. Negative battery cable.
PARTS INFORMATION
PARTS NAME GROUP
Control, EGR Vacuum ................ 3.670
Gasket, EGR Valve .................. 3.680
Valve, EGR ........................ 3.670

6E3-C7-4 5.OL (VIN F) €4 5.7L (VIN 8) DRIVEABILITY AND EMISSIONS
CHART C-7
EXHAUST GAS RECIRCULATION CHECK
5.OL (VIN F) & 5.7L (VIN 8) "F" SERIES (PORT)
Circuit Description:
The exhaust gas recirculation (EGR) valve is controlled by a normally open pulse width modulated (PWM)
solenoid. The ECM turns the solenoid "OFF" to allow vacuum to pass to the EGR and turns the solenoid "ON"
to prohibit EGR operation. When EGR is commanded, the solenoid is turned "ON" and "OFF" many times a
second (duty cycle).
The duty cycle is calculated by the ECM based on information from the coolant, MAT, TPS, and MAF
sensors. Also, engine
rpm's and the PIN switch input affect EGR.
There should be no EGR when in park or
neutral, TPS below
a calibrated value or TPS indicating WOT.
With the ignition "ON" and engine stopped, the EGR solenoid is de-energized. The solenoid, however,
should be energized if the diagnostic terminal is grounded with the ignition "ON" and engine not running.
Test Description: Numbers below refer to circled 2. As soon as back pressure is available at the EGR
numbers on the diagnostic chart.
valve, the bleed portion in the valve should open
1. This will test the solenoid value to determine if it
and cause the valve to go to its heated position.
is capable of closing off the manifold vacuum from
3. 'I'he EGR will be inoperative if the PIN switch is
the EGR valve. The vacuum may bleed off slowly
misadjusted or faulty. Use "Scan" tool and check
but this should not be considered a fault.
PIN switch. Refer to CHART C-1.