1987 MAZDA 626 Workshop Manual

EEC SYSTEM
4B

TROUBLESHOOTING
Check
the
condition
of the
wiring harness
or
connectors, before checking
the
sensors
or
switches.
Note
Make the system inspection first.
If no
problem
is
found, continue with
the
next system
inspection
of the
Troubleshooting Guide. (Refer
to
pages 4B—7 and
8.)

Possible cause

Vacuum
switch

valve
Solenoid

valve
(Purge
control)

0)
<0
m
i
>
« «
o
•C
?

o ** «0 a a

No.1
purge

control

valve
No.2
purge
control
valve
Water
thermo
valve

o E tm 0) £
«>
0)
^
>
Engine

control
unit
terminal
System inspection Vacuum
switch

valve
Solenoid

valve
(Purge
control)

No.1
purge

control

valve
No.2
purge
control
valve
Water
thermo
valve
$
>
2P
System inspection

Page 4B—77 4B—78 4B—78 4B—79 4B—77 4B—77 4B—78 4B—97 4B—90 4B—76
Checking order 3 2 9 10 4 5 6 7 8 1
76G04B-105
4B—75

4B EEC SYSTEM
86U04A-139
86U04A-141
System Inspection
1. Check the vacuum hose routing.
2. If there is a poor connection, clog, or leak, repair
or replace as necessary.
3. Warm up the engine and run it at idle.
4. Disconnect vacuum hose A from No.
1
purge con-
trol valve and connect the SST to the hose.
86 U 04 A-140
5. Increase the engine speed to above 2,500 rpm
and verify that the gauge shows more than 150
mmHg (5.9 inHg).
6. If not correct, check the water thermo valve.
7. Reconnect hose A to No. 1 purge control valve.
8. Disconnect vacuum hose B from the canister and
place a finger over the end of the hose.
9. Accelerate the engine rapidly and check that vacu-
um is felt at above 1,500 rpm.
10. Reconnect hose B to the canister.
11. Disconnect vacuum hose C from the canister and
place a finger over the end of the hose.
12. Check that vacuum is felt.
13. If not correct, check the vacuum line between the
canister and the dynamic chamber for clogging.
86U04A-142
4B—76

EEC SYSTEM 4B
86U04A-143
86 U 04 A-144
86U04A-145
14. Disconnect the evaporation hose from the evapo-
ration pipe.
15. Connect the vacuum pump to the evaporation
pipe.
16. Operate the vacuum pump and verify that no vacu-
um is held.
17. If vacuum is held, check the evaporation pipe for
clogging.
No. 1 Purge Control Valve
1. Blow through the purge control valve from port A
and check that air does not flow.
2. Connect a vacuum pump to the purge control
valve.
3. Apply 110 mmHg (4.33 inHg) vacuum, and blow
through port A again; air should flow.
No. 2 Purge Control Valve
1. Disconnect vacuum hose B from the evaporation
pipe.
2. Blow through the hose and verify that air flows
freely.
Vacuum Switch Valve
1. Remove vacuum switch valve.
2. Connect a vacuum pump to the valve.
3. Blow through the valve from port A and verify that
air comes out of port B when vacuum is applied.
Specified vacuum:
66—106 mmHg (2.6—4.2 inHg)
86U04A-146
4B-77

4B EEC SYSTEM
Water Thermo Valve
1. Remove the water thermo valve.
2. Immerse the valve in a water-filled container.
3. Heat the water gradually and observe the tem-
perature.
4. Blow through the valve from one vacuum port and
verify that air comes out of the other port at
46—54°C (115—129°F).
86U04A-147
Three-way
check valve
86U04A-148
To canister
Pressure valve
3<> A To tank
Vacuum valve
Air filter
Three-Way Check Valve
1. Remove the check valve.
2. Blow through the valve from port A, and check that
air comes out of port B.
Next, block port B and check that air comes out
of port C.
3. Block port B.
4. Connect a vacuum pump to port A and verify that
no vacuum is held.
86U04A-149
Solenoid valve (Purge control)
Solenoid Valve (Purge control)
1. Remove the solenoid valve.
76G04B-128
4B-78

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