1987 MAZDA 626 Exhaust

EGR SYSTEM 4B
EXHAUST GAS RECIRCULATION
(EGR)
SYSTEM
EGR modulator valve Solenoid valve (EGR)
86U04A-127
This system introduces exhaust gas into the intake manifold to reduce NOx in the exhaust gas. It oper-
ates depending on the engine load, engine speed (above 1,500 rpm), engine coolant temperature
(above 70°C, 158°F), and radiator coolant temperature (above 17°C, 63°F).
COMPONENT DESCRIPTIONS
Component Function Remarks
EGR control valve Recirculates portion of exhaust gas
EGR modulator valve Controls vacuum acting on EGR control
valve
Engine control unit Detects signals from input sensors and switches; controls solenoid valve (EGR)
Ignition coil (-) terminal Detects engine speed; sends signal to engine control unit
Solenoid valve (EGR) Controls vacuum line to EGR control
valve
Throttle sensor Detects throttle valve opening angle; sends signal to engine control unit Integrated idle switch
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Water thermo switch Detects radiator coolant temperature; sends signal to engine control unit
ON: above 17°C (63°F)
76G04B-102
4B-71

EGR SYSTEM 4B
Apply 12V
Air filter
L
Jt Port
4. Disconnect the solenoid valve connector.
5. Connect 12V and a ground to the terminals of the
solenoid valve.
6. Blow through the solenoid valve from vacuum hose
A.
7. Check that air flows from the valve air filter.
86U04A-132
86U04A-133
86U04A-134
EGR Modulator Valve
1. Remove the EGR modulator valve.
2. Plug the No. 1 port and connect a vacuum pump
to the No. 3 port.
3. Blow into the exhaust gas port. Operate the vacu-
um pump and verify that vacuum is held.
4. Release the exhaust gas port and confirm that
vacuum is released.
EGR Control Valve
1. Manually actuate the valve by pushing on the di-
aphragm with finger.
2. Check that the spring resistance is present and the
diaphragm moves freely with no sticking or
binding.
Note
Before replacing the EGR control valve, check
the intake air and control systems.
3. Warm up the engine and run it at idle.
4. Connect a vacuum pump to the valve and apply
vacuum.
5. Check that the engine runs roughly or stalls at more
than the specified vacuum.
Specification:
40—60 mmHg (1.6—2.4 inHg)
6. If not correct, replace the EGR control valve.
86U04A-135
4B-73

EXHAUST SYSTEM 4B
EXHAUST SYSTEM
f
76G04B-107
The catalytic converter is used to reduce CO, HC and NOx. The converter contains a compound of
platinum and rhodium. It is a three-way catalyst type with a volume of 1,600 cc (98 cu in).
4B—81

4B EXHAUST SYSTEM
REMOVAL AND INSTALLATION
1. Remove in the sequence shown in the figure.
2. Install in the reverse order of removal.
Torque Specifications
1. Main silencer
2. Middle pipe
3. Pre-silencer
86U04A-159
4. Catalytic converter
5. Bracket
6. Front pipe
INSPECTION
1. Check the catalytic converter and exhaust pipe for
deterioration or restriction.
2. Check the insulation covers welded onto the cata-
lytic converter for damage.
Note
If the insulation cover is touching the catalytic
converter housing, excessive heat at the floor
will occur.
86U04A-160
4B—82

4C
FUEL AND EMISSION
CONTROL SYSTEMS
(FUEL INJECTION FE DOHC)
OUTLINE 4C— 2
COMPONENT APPLICATION 4C— 2
SYSTEM DIAGRAM 4C— 3
COMPONENT LOCATION 4C— 4
VACUUM HOSE ROUTING
DIAGRAM 4C— 7
SPECIFICATIONS 4C— 8
TROUBLESHOOTING GUIDE 4C— 9
TROUBLESHOOTING WITH SST.. 4C— 11
INSPECTION PROCEDURE 4C— 12
PRINCIPLE OF CODE CYCLE 4C— 13
CODE NUMBER 4C— 14
SWITCH MONITOR FUNCTION 4C— 25
INSPECTION PROCEDURE 4C— 26
IDLE ADJUSTMENT 4C— 29
IDLE SPEED 4C— 29
IDLE MIXTURE 4C— 30
INTAKE AIR SYSTEM 4C— 31
COMPONENT DESCRIPTION 4C— 31
REMOVAL 4C— 32
PARTS INSPECTION 4C— 33
REPLACEMENT 4C— 36
INSTALLATION 4C— 37
VARIABLE INERTIA CONTROL
(VIC) SYSTEM 4C— 39
COMPONENT DESCRIPTION 4C— 40
TROUBLESHOOTING 4C— 40
IDLE SPEED CONTROL
(ISC) SYSTEM 4C— 44
COMPONENT DESCRIPTION 4C— 45
TROUBLESHOOTING 4C— 46
REMOVAL 4C— 48
FUEL SYSTEM 4C— 49
COMPONENT DESCRIPTION 4C— 50
TROUBLESHOOTING 4C— 51
FUEL PRESSURE RELEASE AND
SERVICING FUEL SYSTEM 4C— 52
MULTI-PRESSURE TESTER 4C— 53
FUEL PUMP 4C— 56
PULSATION DAMPER 4C— 57
INJECTOR 4C— 57
TRANSFER PUMP CONTROL
SYSTEM 4C— 59
REPLACEMENT 4C— 60
FUEL TANK 4C— 65
PRESSURE REGULATOR
CONTROL (PRC) SYSTEM 4C— 68
COMPONENT DESCRIPTION 4C— 69
TROUBLESHOOTING 4C— 69
DECELERATION CONTROL
SYSTEM 4C— 72
COMPONENT DESCRIPTION 4C— 73
TROUBLESHOOTING 4C— 73
ELECTRONIC SPARK ADVANCE
(ESA) CONTROL SYSTEM 4C— 75
COMPONENT DESCRIPTION 4C— 76
TROUBLESHOOTING 4C— 76
EXHAUST GAS RECIRCULATION
(EGR) SYSTEM 4C- 77
COMPONENT DESCRIPTION 4C— 77
TROUBLESHOOTING 4C— 78
EVAPORATIVE EMISSION
CONTROL (EEC) SYSTEM 4C— 80
COMPONENT DESCRIPTION 4C— 80
TROUBLESHOOTING 4C— 81
POSITIVE CRANKCASE
VENTILATION (PCV) SYSTEM.... 4C— 86
COMPONENT DESCRIPTION 4C— 86
PCV VALVE 4C— 86
EXHAUST SYSTEM
(UNLEADED FUEL) 4C— 87
REMOVAL AND INSTALLATION.. 4C— 88
INSPECTION 4C— 88
EXHAUST SYSTEM
(LEADED FUEL) 4C— 89
REMOVAL AND INSTALLATION.. 4C— 90
CONTROL SYSTEM 4C— 91
RELATIONSHIP CHART 4C— 92
EGI MAIN FUSE 4C— 96
CONTROL RELAY 4C— 96
NEUTRAL SWITCH 4C— 97
CLUTCH SWITCH 4C— 97
P/S PRESSURE SWITCH 4C— 97
ENGINE CONTROL UNIT 4C— 98
E/L CONTROL UNIT 4C—102
AIR FLOW SENSOR 4C—103
THROTTLE SENSOR 4C—104
IDLE SWITCH 4C—106
WATER THERMO SWITCH 4C—106
WATER THERMO SENSOR 4C—107
OXYGEN SENSOR 4C—107
DISTRIBUTOR 4C—108
OXYGEN SENSOR HEATER 4C—109
KNOCK SENSOR 4C—109
INTAKE AIR THERMO SENSOR .. 4C—110
76G04C-001

4C OUTLINE
Exhaust System
Unleaded Fuel
Leaded Fuel
76G04C-006
4C—6

TROUBLESHOOTING GUIDE 4C
TROUBLESHOOTING GUIDE
This troubleshooting guide shows the malfunction numbers and the symptoms of various failures.
Perform troubleshooting as described below.
Input sensors and switches
Possible cause
Page
Symptom and No. CO
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Fault Indicated by SST
Code No. 02 03 05 *i 08 09 11 12 *2 15 • 2 17 *2 25 26 *2 27 *2 28 • 2 34 36 • 2 41
Hard start or won't start
(Cranks OK)
Engine stalls
Rough
Idle
During warm up
After warm up
During warm up
After warm up
High idle speed after warm up
Poor acceleration, hesita-tion or lack of power
TROUBLESHOOTING PROCEDURE
Note
Code No. Is to quickly determine which system or unit may be at fault by use of the SST. (Self-Diagnosis Checker 49 H018 9A1 or Digital Code Checker 49 G018 9A0 with Adaptor harness 49 9200 180)
1st: Check input sensors and output solenoid valves with the SST. (Refer to
page
AC—11.)

2nd: Check other switches with the SST. (Refer to page AC—25.)
3rd: Check the following items:
Electrical system
1) Battery condition 2) Fuses
Runs rough on deceleration
Afterburn in exhaust
system
9
10
Poor fuel consumption
Engine stalls or runs
rough after hot starting
11
12
Knocking
Fuel system
1) Fuel level
2) Fuel leakage 3) Fuel filter 4) Idle speed (with test connec-tor grounded)
Engine
1) Compression 2) Overheating
Ignition system 1) Ignition spark
2) Ignition timing (with test connec-tor grounded)
Intake air system 1) Air cleaner element 2) Vacuum or air leakage 3) Vacuum hose routing 4) Accelerator cable
Others 1) Clutch slippage
2) Brake dragging
Fails emission test 4th: Check Fuel and Emission Control Systems. (Refer to page 4C—10.)
*1..
*2„
.Leaded fuel
.Unleaded fuel
76G04C-009
4C—9

4C TROUBLESHOOTING GUIDE
The Troubleshooting Guide lists the systems most likely to cause
a
given symptom. After finding which
system(s)
to
check, refer
to the
pages shown
for
detailed guides.
iSystem
S UJ 1-tn > tn

INTAKE

AIR
SYSTEM
FUEL
SYSTEM

o oc a
_i o oc 1-z o o oc o i-<
-i
o UJ OC Ul oc 3 (0 tn Ul oc a.
IDLE

SPEED
CONTROL
(ISC)
SYSTEM
ELECTRONIC
SPARK
ADVANCE

(ESA)

CONTROL
SYSTEM

EXHAUST

GAS
RECIRCULATION

(EGR)

SYSTEM

EVAPORATIVE

EMISSION

CONTROL
(EEC)
SYSTEM
POSITIVE
CRANKCASE
VENTILATION
(PCV)
SYSTEM
DECELERATION
CONTROL
SYSTEM

EXHAUST

SYSTEM

VARIABLE

INERTIA
CONTROL
(VIC)
SYSTEM

Page

4C—31 4C—49 4C—68 4C—44 4C—75 4C—77 4C—80 4C—86 4C—72 4C—87
&
89
4C—39
2 3 2 — — 1 — — — — — —
3
4 3 — 1 — 2 — _ _ — — 3 5 4 — 2 — 3 — 1 — — —
4 5 4 -1 — 3 — 2 — — -4 6 5 — 2 — 3 4 1 — — —
o z 5 2 3 — 1 — — — — — — —
E o 6 3 4 — — — 1 2 — — 6 5
Q-E >> 7 4 3 — 2 — — — — 1 — —
(0 8 3 4 — 1 — — — — 2 — —
9 — 2 — — — 3 — — 1 5 4
10 — 2 1 — — — — — — — —
11 — — — — 1 — — — — — —
12 6 7 — 4 — 2 5 _ 3 1
76G04C-010
The numbers
of the
list show
the
priorities
of
inspections, from
the
most possible system
to
that with
the lowest possibility.
These were determined
on the
following basis:
• Ease
of
inspection
•
Most possible system
•
Most possible point
in
system
4C—10