1987 MAZDA 626 Exhaust

4B OUTLINE
Exhaust System
4B—4

TROUBLESHOOTING GUIDE 4B
TROUBLESHOOTING GUIDE
This troubleshooting guide shows the malfunction numbers and the symptoms of various failures.
Perform troubleshooting as described below.
Possible cause
Symptom
Input sensors and switches
o> Q.
C
0
Jh c 01
4B-14
a> 4)
E
o
4B-1S
o in c « m o E k_ 0) c.
0 <0 £
4B-16
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a>
.x
co
4B-17
o 10 c a) co
4B-18
o in c a> (0
o> o> a>
a) £ a VI o E
4B-19
0 <0 c a> 0) c a> 01
S? o
4B-20
E a> in (0
o 10 A •o 0) 0> u.
4B-21
Output solenoid valves
o «
3 O) 0)
0) 0) 01
0> > 10 >
•o o c V o tt)
4B-22
0)
OI

0> > CO >

TJ
O c 0> o CO
4B-23
oc O u
o> > 75 >
•o o c a> o 05
4B-23
0 a. 3 1
2
0) > (0 >
"D O
o 0> in in a a >. £
4B-23
ffl a 3 • a>
2
a> > 10 >
"O o c a> o
CO Q. >. JO
4B-24
Fault Indicated by SST
Code No. 01 08 09 10 12 14 15 17 25 26 28 34 35
Hard start or won't start
(Cranks OK)
Engine stalls
Rough
idle
While warming up
After warming up
While warming up
After warming up
High idle speed after
warming up
TROUBLESHOOTING PROCEDURE
Note
Step 1 under symptom is to quickly determine what system or unit may be at fault by use of the SST. (Self-Diagnosis Checker 49 H018 9A1)
1st:
Check input sensors and output solenoid valves with the
SST.
(Refer
to
page 4B—10.)

2nd:
Check other switches with the
SST.
(Refer
to
page 4B—26.)

3rd:
Check the following items:

11
Poor acceleration, hesita-
tion or lack of power
Runs rough on deceleration
Afterburn in exhaust system
Poor fuel consumption
Engine stalls or rough after hot starting
Electrical system
1) Battery condition
2) Fuses

Fuel system
1) Fuel level 2) Fuel leakage
3) Fuel filter 4) Idle speed

Engine
1) Compression 2) Overheating

Ignition system

1) Ignition spark 2) Ignition timing

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 4B—8.)

76G04B-003
4B—7

4B TROUBLESHOOTING GUIDE
The Troubleshooting Guide lists the systems most likely
to
cause
a
given symptom. After finding
sys-

tems
to
check, refer
to
the
pages shown
for
detailed guides
for
each system.

Possible
cause

Fuel
and
Emission Control Systems

Possible
cause
Intake
Air
System
(Poor
connection
of
components,
throttle
body)

Fuel

System
(Fuel

injection,

Fuel
pressure)
Pressure
Regulator
Control
System
Idle-up
System

(Air

valve,
solenoid
valve
malfunction)

EGR

System

(EGR

control
valve
stuck
and
open)

EEC

system
(Vacuum
switch
valve,
No.1
purge
control
valve
malfunction)
PCV

System
(System

clogged)

Deceleration

System
(Dashpot,
fuel
cut
operation
malfunction)

Air

injection

system
(Reed
valve
malfunction)
Exhaust
system

(System

clogged)

Page 4B—30 4B—42 4B—53 4B—35 4B—71 4B—74 4B—80 4B—64 4B—68 4B—81

Symptom

2
2 1

Symptom

3

4 3 1 2

Symptom

3
5 4 2 3 1

Symptom

4
6 5 1 4 2 3

Symptom

4
7 6 2 4 5 1 3

Symptom

5
3 1 2

Symptom
6
3 4 1 2 5
Symptom

7
3 2 1

Symptom

8
3 4 1 2

Symptom

9
2 3 1 4

Symptom

10
2 1

Symptom

11
7 8 5 2 6 3 4 1

76G04B-004
The numbers
of
the list show the priorities
of
inspections from the most possible to that with
the
lowest
possibility.
These were determined
on the
following basis:
• Ease
of
inspection
•
Most possible system
•
Most possible point
in
system
4B—8

IDLE-UP SYSTEM 4B
TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the sensors or switch.
Possible
cause
\ Page
Symptom
Air valve
Air bypass solenoid valve Engine control unit
terminal
Possible
cause
\ Page
Symptom
Air valve
Idle-up singal Adjustment
Engine control unit
terminal
Possible
cause
\ Page
Symptom
Air valve
Idle-up singal Adjustment
1S 20
Possible
cause
\ Page
Symptom 4B—38 4B—39 4B—40 4B—89 4B—90
Engine
stalls
While warming up
1 2 3 4 5
Engine
stalls After warming up
1 2 3 4

Rough Idle
While warming up
1 2 3 4 5
Rough Idle After warming up
1 2 3 4

High idle speed after warming up
1 2 3 4 5

Runs rough on deceleration
1 2 3 4

Afterburn in exhaust system
1 2 3 4 5

Fails emission test
1 2 3 4 5

76G04B-045
4B-37

4B FUEL SYSTEM
TROUBLESHOOTING
Check
the
condition
of
the wiring harness and connectors before checking
the
sensors
or
switches.
Possible
cause
Page

V
S E
i
o

o V)
0
e
~
0)
Ju
»
•E
<»
CL
01
3
0
<0
1
£
Oxygen

sensor

s c V
in
V

P
o E k_

•E **
l_
h
O
v
w
Water
thermo
switch

Q.
E
3 Q.
u

Injector

£ 3 3 o d
aj
Engine
con-
trol unit terminal
< £
8
<
Q. Oxygen

sensor

£ t->
0)
>
M Water
thermo
switch
3
u.
Injector
3
u. 3C
3E
3B
Symptom 4B-94 4B-99 4B—98 4B-95 48—97 4B-97 4B-49 4B-S1 4B-48 4B-90 4B-90
Hard start
or
won't start (Cranks
OK)
5 4 1 3 2

Engine While warming
up
4 3 2 1 5

stalls After warming
up
1 3 2 4

Rough Idle While warming
up
4 3 2 1

Rough Idle After warming
up
1 2 4 3

Poor acceleration, hesitation,
or

lack
of
power
1 3 4 2

Runs rough
on
deceleration
1 2

Afterburn
in
exhaust system
1 2

Poor fuel consumption
5 6 4 3 2 1

Falls emission test
1 2

Engine stalls
or
rough after
hot
starting
1 3 2

76G04B-059
4B—44

4B DECELERATION CONTROL SYSTEM
TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the sensor or switches below.
Note
Make the system inspection first. If no problem is found, continue with the next system
inspection of the Troubleshooting Guide. (Refer to page 4B—7 and 8.)
Possible
^^ cause
Symptom
Dashpot Water thermo
sensor
Electrical signal
inspection
(Injector)
Possible
^^ cause
Symptom 4B—67 4B—97 4B-66
High idle speed after warming up 1
Runs rough on deceleration 1 3 2
Afterburn in exhaust system 1 3 2
Poor fuel consumption 1 3 2
Fails emission test 1 3 2
76G04B-090
Electrical Signal Inspection (Injector)
1. Connect the SST between the wiring harness and
engine control unit.
2. Set 3C or 3E position on the SST.
Note
3C — For No. 2 and No. 4 injectors
3E — For No. 1 and No. 3 injectors
76G04B-091
0-6V 0-20V
3. Check that the indicator lamps alternately flash at
idle.
86U04A-125
4B—66

4B AIR INJECTION SYSTEM
AIR INJECTION SYSTEM
76G04B-095
This system supplies secondary air into the exhaust system to improve idle stability.
COMPONENT DESCRIPTIONS
Component Function Remark
Air cleaner Filters air entering throttle body
Air control valve Directs air to reed valve Installed on air cleaner
Reed valve Directs air to exhaust manifold Improves idle stability
76G04B-096
4B—68

4B AIR INJECTION SYSTEM
56G04B-114p
76G04B-100
76U04A-066
2. Connect a vacuum pump to the valve.
3. Apply vacuum gradually and check that the stem
starts to move as specified.
Specification:
180—280 mmHg (7.1—11.0 inHg)
Reed Valve
Inspection
1. Warm up the engine and run it at idle.
2. Disconnect the vacuum hose from the air control
valve and plug it.
3. Attach a vacuum pump to the air control valve and
apply 500 mmHg (19.7 inHg) vacuum.
4. Check that air is sucked into the air passage.
5. Increase the engine speed to 2,500 rpm.
6. Check that exhaust gas is not emitted from the
passage.
7. If not correct, replace the reed valve.
Replacement
1. Remove in the sequence shown in the figure.
1) Housing
2) Attaching plate
3) Reed valve
4) Seal rubber
2. Install in the reverse order of removal.
76G04B-101
4B—70