1987 MAZDA 626 Workshop Manual

4C CONTROL SYSTEM
Jjf (Terminal A)
n PI
WRED r^j
BLACK
BLACK 1 (Terminal C)
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Replacement
1. Disconnect the connector.
2. Loosen the air hose clamps.
3. Replace the air flow sensor.
Caution
Install the air flow sensor so that the arrow on
the sensor aligns with air flow direction.
4. Tighten the hose clamps.
5. Reconnect the connector to the sensor.
THROTTLE SENSOR
Caution
Use a precision voltmeter with a scale of 0.01V
to inspect or adjust the throttle sensor. If it
is not available, replace the throttle sensor
and throttle body as an assembly.
Inspection
1. Disconnect the throttle sensor connector (3-pin).
2. Connect the SST between the throttle sensor and
the wiring harness.
3. Turn the ignition switch ON.
4. Measure BLACK and RED wire voltages.
Specifications:
BLACK—Approx. OV
RED—4.5—5.5V
5. If not correct, check the battery voltage and wir-
ing harness. If these are OK, replace the engine
control unit.
6. Using the RED wire voltage as a guide, find the
specified BLUE wire voltage ranges in the table.
RED wire voltage
Specified range (V) RED wire voltage Fully close Fully open
4.90—4.99V 0.40-0.58 3.90-4.60
5.00—5.09V 0.41—0.60 3.97-4.70
5.10-5.19V 0.42—0.61 4.05—4.79
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CONTROL SYSTEM 4C
7. Make sure that the throttle valve is fully closed.
8. Check that the BLUE wire voltage is within the
specified range.
9. Adjust the throttle sensor if necessary
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10. Open the throttle valve fully.
11. Check that BLUE wire voltage is within the speci-
fied range.
12. If not correct, replace the throttle sensor.
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13. Turn the ignition switch OFF.
14. Disconnect the SST and reconnect the throttle sen-
sor connector.
15. Disconnect the negative battery terminal and de-
press the brake pedal for 5 seconds to eliminate
the malfunction memory from the control unit.
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Adjustment
1. Perform steps 1 to 7 in the inspection procedure.
2. Connect the voltmeter to the BLUE wire.
3. Loosen the throttle sensor mounting screw.
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4C CONTROL SYSTEM
4. Make sure that the throttle valve is fully closed.
5. Turn the throttle sensor so that the BLUE wire volt-
age indicates within the specified closed range.
6. Tighten the throttle sensor mounting screw.
7. Recheck that the BLUE wire voltage is within the
specified range.
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8. Turn the ignition switch OFF.
9. Disconnect the SST and reconnect the throttle sen-
sor connector.
10. Disconnect the negative battery terminal and de-
press the brake pedal for 5 seconds to eliminate
the from the malfunction memory from the control
unit.
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76G04C-198
4C-106
IDLE SWITCH
Inspection
1. Disconnect the idle switch connector.
2. Check continuity between the switch and a ground.
Throttle valve condition Continuity
Fully closed Yes
Open No
3. If not correct, check condition of the wiring harness
of the idle switch. Replace the idle switch and throt-
tle body as an assembly, if necessary.
WATER THERMO SWITCH
Inspection
1. Remove the switch from the radiator.
2. Place the switch in water with a thermometer and
heat the water gradually.
3. Check for continuity of the switch with an
ohmmeter.
Coolant temp. Continuity
More than approx. 17°C (63°F) Yes
Less than approx. 10°C (63°F) No
4. If not correct, replace the water thermo switch.

CONTROL SYSTEM 4C
WATER THERMO SENSOR
Inspection
1. Remove the water thermo sensor.
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2. Place the sensor in water with a thermometer and
heat the water gradually.
3. Check resistance of the sensor with an ohmmeter.
Coolant Resistance
-20°C ( —4°F) 14.5—17.8 kfl
20°C ( 68°F) 2.2-2.7 kQ
40°C (104°F) 1.0—1.3 kQ
60°C (140°F) 500—640 O
80°C (176°F) 280—350 fl
4. If not correct, replace the water thermo sensor.
OXYGEN SENSOR
Inspection of Output Voltage
1. Warm up the engine and run it at idle.
2. Disconnect the oxygen sensor connector.
3. Connect a voltmeter between the oxygen sensor
and a ground.
4. Run the engine at 4,500 rpm until the voltmeter
indicates approx. 0.7V.
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5. Increase and decrease the engine speed suddenly
several times. Check to see that when the speed
is increased the meter reads between 0.5V—1 .OV,
and when the speed is decreased it reads between
OV—0.4V.
6. If the voltmeter dosen't indicate as specified, re-
place the oxygen sensor.
86U04A-206
4C—107

4C CONTROL SYSTEM
Check connector: Green (6 pin)

cable
49 H018 9A1
Inspection of Sensitivity
1. Warm up the engine to the normal operating tem-
perature and run it at idle.
2. Connect the SST to the check connector.
Note
Digital code checker (49 G018 9A0) can be
used.
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Increase the engine speed to between 2,000 and
3,000 rpm, and check that the monitor lamp flash-
es for 10 seconds.
Monitor lamp: Flashes ON and OFF
more than 8 times/10 sec
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A B C D
/llkw^ - ®
I « ^
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4C—108
DISTRIBUTOR
On-vehicle Inspection
1. Remove the rubber boot from the distributor con-
nector.
2. Run the engine at idle.
3. Check terminal voltage with a voltmeter.
Terminal Voltaae
A (G signal) 1.0—2.4
B (Ne sianaB 1.8—2.2
C (Power supply) Approx. 12V
D (Ground) OV
4. If not correct, check the wiring harness for an open
or short circuit, then check the distributor for G sig-
nal or Ne signal.

CONTROL SYSTEM 4C
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76G04C-204
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G Signal Inspection
1. Remove the distributor. (Refer to section 5.)
2. Reconnect the distributor to the wiring harness.
3. Remove the rubber boot from the distributor con-
nector.
4. Connect a volt meter between the A terminal and
a ground.
5. Turn the shaft and check that the distributor gener-
ates one pulse signal I per one turn.
Ne signal Inspection
1. Remove the distributor. (Refer to Section 5.)
2. Reconnect the distributor to the wiring harness.
3. Remove the rubber boot from the distributor con-
nector.
4. Connect a voltmeter between the B terminal and
a ground.
5. Turn the shaft and check that the distributor gener-
ates four pulse signals per one turn.
Oxygen Sensor Heater
1. Disconnect the oxygen sensor connector.
2. Check resistance between terminals B and C.
Specification: approx. 6 Q
Knock Sensor (Leaded fuel)
1. Warm up the engine and rum it at idle.
2. Ground the test connector (Green, 1-pin) with a
jumper wire.
3. Tap the engine hanger with a hammer and verify
that the ignition timing retards.
4. If not correct, check the knock sensor.
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4C-109

4C CONTROL SYSTEM
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76G04C-208
Replacement
1. Disconnect the knock sensor connector.
2. Lift the vehicle and remove the intake manifold
bracket.
3. Remove the knock sensor with the SST.
4. Install the knock sensor in the reverse order of
removal.
INTAKE AIR THERMO SENSOR (DYNAMIC
CHAMBER)
Inspection
1. Disconnect the intake air thermo sensor connector.
2. Connect an ohmmeter to the sensor terminals.
3. Check the resistance of the sensor.
Temperature Resistance (kQ)
20°C (68°F) 29.7—36.3
50°C (122°F) 8.4-10.2
85 °C (185°F) 2.5-3.1
4. Reconnect the sensor connector.
Replacement
1. Disconnect the intake air thermo sensor connector.
2. Remove the sensor.
3. Install the sensor.
Note
When installing the sensor, tighten to the
specified torque.
Specified torque:
6.9—8.8 N-m (0.7—0.9 m-kg, 72 in-lb)
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4C—110

4D
FUEL AND EMISSION
CONTROL SYSTEM
(DIESEL)
OUTLINE 4D— 2
SPECIFICATIONS 4D— 2
TROUBLESHOOTING GUIDE 4D— 3
ON-VEHICLE MAINTENANCE 4D— 4
AIR CLEANER ELEMENT 4D— 4
WATER DRAINING 4D— 4
AIR BLEEDING 4D— 4
INJECTION TIMING 4D— 5
IDLE SPEED 4D— 6
EXHAUST SMOKE 4D— 6
INTAKE AIR SYSTEM 4D— 7
STRUCTURAL VIEW 4D— 7
AIR DUCT AND AIR CLEANER 4D— 8
INTAKE MANIFOLD 4D— 9
SUPERCHARGING SYSTEM (RF-CX) 4D-10
TROUBLESHOOTING GUIDE 4D—10
ON-VEHICLE INSPECTION 4D—11
COMPREX SUPERCHARGER 4D—13
STARTING VALVE 4D—15
INTERCOOLER 4D—16
BOOST AIR TEMPERATURE SENSOR 4D—17
EXHAUST SYSTEM 4D—18
STRUCTURAL VIEW 4D—18
EXHAUST MANIFOLD 4D—19
EXHAUST PIPE AND MAIN SILENCER .... 4D—20
FUEL SYSTEM 4D—21
STRUCTURAL VIEW 4D—21
FUEL FILTER 4D—22
SEDIMENTER (GENERAL) 4D—22
WATER LEVEL SENSOR 4D—23
INJECTION PUMP 4D—24
INJECTION NOZZLE 4D—31
FUEL TANK 4D—34
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