1987 MAZDA 626 engine

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
COMPONENT LOCATION
Input and Output Devices
Solenoid Solenoid Idle valve valve switch /nnA
Solenoid
valve*1 Solenoid valve*1
'(No.1 purge control)
E/L control unit
Engine control unit
Control relay
Knock sensor*2
Water thermo
switch*1
Oxygen Distributor
sensor*1
Clutch switch
\ Oxygen sensor
\ relay*1
Solenoid valve*1 (EGR)
Solenoid valve (ISC)
Air flow sensor
Neutral switch
Water thermo sensor
*1...Unleade fuel only
*2...Leaded fuel only
76G04C-004
4C—4

4C OUTLINE
SPECIFICATIONS
Item Engine type Unleaded Fuel Leaded Fuel
Idle speed rpm 750 ± 50
Throttle body
Type Horizontal draft (2-barrel)
Throat diameter mm (in) No. 1 46 (1.8) Throat diameter mm (in) No. 2 40 (1.6)
Fuel pump
Type Impeller (in tank)
Output pressure kPa (kg/cm2, psi) Main pump: 441-588 (4.5—6.0, 64—85) Transfer pump: 20—25 (0.20—0.25, 2.8—3.6)
Feeding capacity cc (cu in)/10 sec. Main pump: More than 220 (13.4) Transfer pump: More than 190 (11.6)
Fuel filter
Type Low pressure side Nylon element Type High pressure side Paper element
Pressure regulator
Type Diaphragm
Regulating pressure kPa (kg/cm2, psi) 235-275 (2.4 -2.8, 34-40)
Injector
Type High-ohmic
Type of drive Voltage
Resistance G 12--16
Injection amount cc (cu in)/15 sec. 66-91 (4.03-5.55)
Idle speed control valve
Solenoid resistance a 6.3--9.9
Fuel tank
Capacity liters (US gal, Imp gal) 60 (15.9, 13.2), 57 (15.0, 12.5): 4-wheel steering vehicle
Air cleaner
Element type Dry
Fuel
Specification Unleaded (95 RON or more) Leaded or unleaded fuel
(95 RON or more)
76G04C-008
4C-8

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

TROUBLESHOOTING WITH SST 4C
TROUBLESHOOTING WITH SST
Engine control unit
76G04C-011
When troubles occur in the main input devices or output devices, check for the cause with the SST
(Self-Diagnosis checker 49 H018 9A1 or Digital code checker 49 G018 9A0 with Adaptor har-
ness 49 9200 180)
Failure of individual input and output devices is indicated and retrieved from the control unit as mal-
function code numbers.
Note
The control unit constantly checks for malfunction of the input devices. But, the control
unit checks for malfunction of output devices only in a 3 second period after the ignition
switch is turned ON and the test connector is grounded.
4C—11

4C TROUBLESHOOTING WITH SST
Check connector: (Green, 6 pin)
49 H018 9A1
86U04A-011
Test connector: (Green, 1 pin)'
INSPECTION PROCEDURE
1. Connect the SST to the check connector. (Green,
6-pin) and the negative battery terminal.
2. Set the select switch to position A.
Note
The check connector is located at the rear of
the left side wheel housing.
3. Ground the test connector (Green, 1-pin) with a
jumper wire.
Note
The test connector is located near the Self-
Diagnosis Checker check connector.
86U04A-012
OO
uu
SELF-DIAGNOSIS CHECKER
MONITOR LAMP SELECT SW «

o o o
o
76G04C-012
4. Turn the ignition switch ON.
5. Verify that 88 flashes on the digital display and that
the buzzer sounds for three seconds after turn-
ing the ignition switch ON.
6. If 88 does not flash, check the control relay (refer
to page 4C—96), power supply circuit, and check
connector wiring.
7. If 88 flashes and the buzzer sounds continuously
for more than 20 seconds check the check con-
nector wiring, then replace the engine control unit
and perform steps 3 and 4 again.
8. Note the code numbers and check for the causes
by referring to the check sequences shown on
pages 4C—16 to 4C—24. Repair as necessary.
Note
Cancel the code numbers by performing the
after-repair procedure after repairing.
AFTER-REPAIR PROCEDURE
1. Cancel the memory of malfunctions by disconnect-
ing the negative battery cable and depress the
brake pedal for at least five seconds.
76G04C-013
4C-12

TROUBLESHOOTING WITH SST 4C
49 H018 9A1
negative battery cable
^ll
Test connector: (Green, 1 pin)
86U04A-015

Ignition switch:
ON

for six
seconds
76G04C-014
2. Connect the SST to the check connector.
3. Ground the test connector (Green, 1-pin) with a
jumper wire.
4. Turn the ignition switch ON for six seconds (do
not start the engine).
5. Start and warm up the engine, then run it at 2,000
rpm for two minutes.
6. Verify that no code numbers are displayed.
PRINCIPLE OF CODE CYCLE
Malfunction codes are determined as shown below
86U04A-017
1. Code cycle break
The time between warning code cycles is 4.0 sec (the time the light is off).
ON
OFF
1 cycle Malfunction code
cycle break
4.0 sec.
86U04A-018
4C—13

TROUBLESHOOTING WITH SST 4C
Malfunction display
Sensor or subsystem Self-diagnosis Fail-safe Malfunction
code no. Malfunction code output signal pattern
Sensor or subsystem Self-diagnosis Fail-safe
08
Air flow sensor Open or short circuit Maintains basic sig-nal at preset value
09 o°pNp II IIL •
Water thermo sensor Open or short circuit Maintains constant 35°C (95°F) command
11 0°FNFJUUL
Intake air thermo sensor (dynamic chamber)
Short circuit Maintains constant 20°C (68°F) command
12
Throttle sensor Open or short circuit Maintains constant command of throttle valve fully open
15 ON n
OFF •L 01
Oxygen sensor Sensor output con-tinues less than 0.55V 120 sec. after engine starts (1,500 rpm or over)
Cancels
EG I
feed-
back operation
17 ON n
OFF L HI il
Feedback system Sensor output not changed 20 sec. af-ter engine starts (1,500 rpm or over)
Cancels
EG I
feed-
back operation
25 0°nfJU1LJIL
Solenoid valve (pres-sure regulator control)
Open or short circuit
26 2LMJIL
Solenoid valve (No.1 purge control)
Open or short circuit
27 ON nn
OFF | _ •111
-ii-Solenoid valve (No.2
purge control)
Open or short circuit
28 ON nn
OFF L Hi nr
Solenoid valve (EGR)
Open or short circuit
34 ^jmiHum
Solenoid valve (Idle speed control)
Open or short circuit
36 °FFJMI«U
Oxygen sensor relay
Open or short circuit
41 <£jimjiuM
Solenoid valve (Vari-able inertia control)
Open or short circuit
76G04C-018
Caution
a) If there is more than one failure present, the lowest number malfunction code is dis-
played first, the remaining codes are displayed sequentially.
b) After repairing a failure, turn off the ignition switch and disconnect the negative battery
cable and depress the brake pedal for at least 5 seconds to erase the memory of a mal-
function code.
4C—15