1988 PONTIAC FIERO Service Repair Manual

6E3-C6-2 5.OL (VIN F) & 5.7L (VIN 8) DRIVEABILITY AND EMISSIONS
Air enters the body of the valve from the pump.
Air pressure builds against the control valve and for:
@ 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 resistance,
i.e., out the
divertlrelief tube to atmosphere. Electrical
failure (open circuit) of the control valve
will divert air flow overboard at all times. Air will
flow to the converter at all times if an open circuit
occurs to the switching valve (converter solenoid).
DIAGNOSIS
The diagnosis of the AIR system is covered in
CHART C-6 at the end of this section.
OPERATIONAL CHECKS
Air Pump
The air pump is a positive displacement vane type
which is permanently lubricated and requires no
periodic maintenance.
llccelerate engine to approximately 1500 rpm's
and observe air flow from hose(s). If air flow increases
as engine is accelerated, pump is operating
satisfactorily. If air flow does not increase or is not
present, proceed as follows:
Inspect
I. For proper drive belt tension.
2. For a leaky pressure relief valve. Air may be
heard leaking with the pump running.
TO CONVERTER AIR INLET
TO EXHAUST PORTS
1 SOLENOID
Figure C6-2 - A.I.R. System Control Valve
Air is diverted to the atmosphere under the
lowing conditions:
Rich operation.
When the
ECM recognizes a problem and sets a
trouble code.
@ During deceleration.
During high rprn operation when air pressure is
greater than the setting
for the internal relief
valve.
RESULTS OF INCORRECT OPERATION
If no air (oxygen) flow enters the exhaust stream
at the exhaust ports, I-IC and CO emission levels will
be too high.
Air flowing to the exhaust ports at all times could
increase temperature of the converter.
Air flowing at all times to the catalytic converter
may cause converter overheating during rich
a ion.
oper
t'
Mechanical failures in the valves could cause the
air to flow incorrectly to the exhaust ports or the
converter.
NOTICE : If the engine or underhood compartment is
to be cleaned with steam or high-pressure
detergent, the centrifugal filter fan should
be masked off to prevent liquids from
entering the pump (see Figure
C6-3).
NOTICE: The AIR system is not completely
noiseless. Under normal conditions, noise
rises in pitch as engine speed increases.
To determine if excessive noise is the fault
of the air injection reactor system, operate
the engine with the pump drive belt
removed. If excessive noise does not exist
with the belt removed proceed as follows:
a inspect
3. For a seized air injection pump.
4. Hoses, tubes and all connections for leaks and
proper routing.
5. For air flow from control/switching valve.
6. AIR injection pump for proper mounting and bolt
torque.
7. If no irregularities exist and the AIR injection
pump noise is still excessive, remove and replace
Pump.
CAUTION: 110 Not Oil Pump

DRlVEABlLlfVAND EMISSIONS 5.OL (VIN F) & 5.7L (VIN 8) 6E3-C6-3
Hoses and Pipes
1. Hose or pipe for deterioration or holes.
2. All hoses or pipe connections, and clamp tightness.
3. Hose or pipe routing. Interference may cause
wear.
4. If
a leak is suspected on the pressure side of the
system or if a hose or pipe has been disconnected
on the pressure side, the connections should be
checked for leaks with a soapy water solution.
With the pump running, bubbles will form if a
leak exists.
Check Valve
Inspect
1. A check valve should be inspected whenever the
hose is disconnected from a check valve or
whenever check valve failure is suspected.
(A
pump that had become inoperative and had shown
indications of having exhaust gases in the pump
would indicate check valve failure).
2. Blow through the check valve (toward the cylinder
head) then attempt to suck back through the check
valve. Flow should only be in one
direction(toward the exhaust manifold). Replace
valve which does not operate properly.
ON-CAR SERVICE
DRIVE BELT
Remove or Disconnect
1. Inspect drive belt for wear, cracks or deterioration
and replace if required. When installing a new
belt, it must be seated and fully secured in grooves
of all belt driven components.
AIR INJECTION PUMP
Remove or Disconnect
1. Hold pump pulley from turning by cotnpressing
drive belt, then loosen pump pulley bolts.
2. Drive belt and pulley.
3. Hoses, vacuum, and electrical connections from
air injection control valve.
4. Air pump mounting bolts, and pump assembly
(See Figure
C6-3).
Install or Connect
3. Pump pulley bolts and tighten equally to 13 N.m
(10 lb. ft).
4. Check air injection system for proper operation
(see CHART C-6).
Figure C6-3 - Air Pump Service
AIR INJECTION CONTROL (PEDES) VALVE
Remove or Disconnect
1. Battery ground cable.
2. Adapter bolts (See Figure C6-4).
3. Air outlet hoses from valve.
4. Splash guardlcover
5. Electrical connectors and vacuum hoses from
valve.
6. Control valve.
Install or Connect
1. Control valve.
2. Electrical connectors.
3. Splash guard/cover.
4. Air hoses to valve.
5. Battery ground cable.
6. checksystem operation (see CHART C-6).
1. Air pump assembly, and tighten mounting bolts
2. Spacer and pump pulley against centrifugal lilter
fan.

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.