MAZDA 626 1987 Workshop Manual

EEC SYSTEM 4B
2. Connect vacuum hoses to the valve as shown in
the figure.
3. Blow air through the valve from hose A and check
that air comes out of the valve air filter.
4. Apply 12V and ground the solenoid valve with jum-
per wires.
5. Blow air through the valve from hose A and check
that the air comes out of port B.
6. Replace, if necessary.
86U04A-151
Separator
1. Remove the separator.
2. Visually check the separator for damage.
3. Replace, if necessary.
86U04A-154
4B-79

4B PCV SYSTEM
POSITIVE CRANKCASE VENTILATION
(PCV)
SYSTEM
76G04B-106
The PCV valve is operated by the intake manifold vacuum.
When the engine is running at idle, the PCV valve is opened slightly and a small amount of blowby
gas is drawn into the dynamic chamber.
At high engine speeds, the PCV valve is further opened and a larger amount of blowby gas is drawn
into the dynamic chamber.
COMPONENT DESCRIPTION
Component Function
PCV valve Controls blowby gas amount pulled into engine
PCV VALVE
1. Warm up the engine to the normal operating tem-
perature and run it at idle.
2. Disconnect the PCV valve and the ventilation hose
from the cylinder head cover.
3. Close the PCV valve opening.
4. Check that vacuum is felt.
4B—80

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

CONTROL SYSTEM 4B
CONTROL SYSTEM
Atmospheric
pressue sensor
Engine control unit
Brake light switch
Clutch switch
Circuti opening
relay
E/L control unit
Air flow meter
Neutral switch
76G04B-129
The control system consists of the input devices and the engine control unit. The engine control unit
controls the fuel injection amount (EGI), fuel injection pressure, bypass air amount, switch monitor func-
tion, and fail-safe function.
4B—83

4B CONTROL SYSTEM
RELATIONSHIP CHART
Input Devices and Output Devices
BRAKE LIGHT SWITCH O X X X X X X X X X
ELECTRICAL LOAD CONTROL UNIT X X X X X X X X O X
P/S PRESSURE SWITCH* X X X X X X X X O X
A/C SWITCH O X X X X O O X X O
IGNITION SWITCH
(STA

POSITION) O O X O X X X X O O
INHIBITOR SWITCH o X X X O X X X X O
NEUTRAL
AND
CLUTCH SWITCH o X X X X X X X X O
OXYGEN SENSOR o X X X X X X X X X
WATER THERMO SWITCH (RADIATOR) o X X X O X X X X X
ATMOSPHERIC PRESSURE SENSOR o X X X X O X O O X
INTAKE
AIR
THERMO SENSOR o X X O X X X O O X
WATER THERMO SENSOR o X X O O O X X o X
IDLE SWITCH o o X O X X X X o X
THROTTLE SENSOR o O X X O X X X X O
AIR FLOW METER o X X X X O X X X X
IGNITION COIL o O X O O O X X o O

INPUT
DEVICES
OUTPUT
DEVICES
FUEL
INJECTION
AMOUNT FUEL
INJECTION

TIMING
PRESSURE
REGULATOR
EGR
PURGE
IDLE-UP
(A)*
IDLE-UP
(B)

IDLE-UP

(C)

rr

INPUT
DEVICES
OUTPUT
DEVICES
INJECTOR
AIR

VALVE
SOLENOID
VALVE
AIR

BYPASS
SOLENOID
VALVE
AIR

CONDITIONEI

76G04B-108
4B-84

CONTROL SYSTEM 4B
Output Devices and Engine Conditions
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76G04B-109
4B-85

4B CONTROL SYSTEM
69G04A-161
86U04A-169
76G04B-130
EGI MAIN FUSE
Inspection
Check the continuity of EGI main fuse.
MAIN RELAY
1. Check that a "clicking" sound is heard at the main
relay when turning the ignition switch ON and OFF.
2. Apply 12V and a ground to (A) and (B) terminals
of the main relay.
3. Check continuity at terminals using an ohmmeter.
-Operation
Terminals 12V Not applied 12V Applied
©- ® No continuity Continuity
CIRCUIT OPENING RELAY
Relay Circuit
1. Remove the circuit opening relay.
2. Check the circuit as described.
Terminal Checkina item Correct result
FD Resistance 0.2-300
Fc Continuity (crankinnl oo
B Voltaae (Ian: ON) Batterv voltaae
STA Voltaae (Crankincri Approx. 9V
Ei Continuity oo
Circuit Opening Relay
Apply 12V and a ground to the terminals below and
check the circuit opening relay as described.
12V Grounded Correct result
STA Ei B FP: Continuity
B Fc Fp: Battery voltage
Resistance
Check the resistance between the terminals using an
ohmmeter.
69G04A-164
Between terminals Resistance (Q)
STA <- E1 15-30
B
<-<•
Fc 80-150
B « Fp 00
4B—86

CONTROL SYSTEM 4B
ENGINE CONTROL UNIT
Engine Signal Monitor (49 9200 162) and Adapter (49 9200 163).
Adapter harness 49 9200 163
Engine wiring harnessN
Selector switch
Monitor switch
Engine control unit
terminal number
Terminals
(A and 8)
ENGINE SIGNAL MONITOR
86U04A-171
The Engine Signal Monitor (49 9200 162) was developed to check the control unit terminal voltages.
This monitor easily inspects the individual terminal voltages through selection of the monitor switch.
How to Use the Engine Signal Monitor
1. Connect the Engine Signal Monitor (49 9200 162) between the engine control unit and the en-
gine harness using the adapter (49 9200 163).
2. Turn the selector switch and monitor switch to select the terminal number.
3. Check the terminal voltage.
Caution
Never apply voltage to terminals A and B.
4B-87

4B CONTROL SYSTEM
Terminal Voltage
If the input and output devices and related wiring are normal, but the engine control unit terminal volt-
age is incorrect, replace the engine control unit.
Terminal Input Output Connection to Voltage (After warming-up) Remarks Terminal Input Output Connection to IGN: ON Idle Remarks
1A — — — — —
1B o Self-Diagnosis Checker (Code number)
For 3sec. after ignition switch OFF ->• ON: below 6.2V (Buzzer sounds) After 3sec.: Battery voltage (Buzzer does not sound)
• Using Self-Diagnosis Check-er and test con-nector grounded • Buzzer sounds: below 6.2V • Buzzer does not sound: Battery voltage
1C — — — — —
1D o Self-Diagnosis Checker (Monitor lamp)
Test connector grounded
For 3sec. after igni-tion switch OFF ON:
below 6.2V (light il-luminates) After 3sec.: Battery voltage (light does not illuminate)
(Test connector grounded) approx. 10V (Test connector not grounded) Monitor lamp ON: below 6.2V Monitor lamp OFF: Battery voltage
With Self-Diagnosis
Checker
1E O Idle switch Accelerator pedal released: below 1.5V
Accelerator pedal depressed: Battery voltage
1F o A/C relay A/C switch ON: below 2.5V A/C switch OFF: Battery voltage
Blower motor ON
1G — — — — —
1H o Water thermo switch Below 1,5V Radiator temp.:
above 17°C (63°F)
11 o Electrical load con-trol unit Electrical load ON: below 1.5V Electrical load OFF: Battery voltage Electrical load: Rear defroster Headlight Blower motor (3rd & 4th position) Electrical fan
1J o Brake light switch Brake pedal released: below 1.5V
Brake pedal depressed: battery voltage
1K — — — — — —
1L o A/C switch A/C switch ON: below 1.5V
A/C switch OFF: battery voltage
Blower motor: ON
1M o Ignition coil © terminal Battery voltage *1 Battery voltage *1 Engine Signal Monitor: green and red lights flash
1N — — — — —
10 — — — —
4B-88