fuel MAZDA 626 1987 Workshop Manual

4B OUTLINE
SPECIFICATIONS
Item Specification

Idle speed rpm MTX: 800 +5„° (Neutral), ATX: 900 +5S
(P
range)

Throttle body

Type Horizontal draft (1 -barrel)
Throat diameter mm (in) 50 (2.0)

Air flow meter

E2-VS More than
20

E2-VC 100-300
Resistor
Q
E2-VB 200—400 Resistor
Q

E2-THA -20°C
(
—4°F) 13,600-18,400 20°C
(
68°F) 2,210-2,690 60°C (140°F)
493- 667
Air cleaner

Element type Oil permeated

Fuel pump

Type Impeller
(in
tank)
Output pressure kPa (kg/cm2,
psi)
441-588 (4.5-6.0, 64—85)
Feeding capacity cc (cu in)/10 sec. 220 (13.4) minmum

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
TvDe
Hiqh-ohmic
Type
of
drive Voltage
Resistance
fi
12-16
Injection amount cc (cu
in) 15
seconds 38—53 (2.3-3.2)

Fuel tank

Capacity liters (US gal, Imp gal) 60 (15.9, 13.2)

Fuel

Soecification Unleaded reaular

76G04B-506
4B—6

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
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4B-14
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4B-1S
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4B-16
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4B-17
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4B-18
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4B-19
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4B-20
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4B-21
Output solenoid valves
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0> > 10 >
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4B-22
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OI

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TJ
O c 0> o CO
4B-23
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4B-23
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4B-23
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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 ADJUSTMENT 4B
76G04B-034
76G04B-035
Idle mixture
Automatic
Control
Function
Engine Control Unit

IDLE
ADJUSTMENT
IDLE SPEED
Preparation
1) Check the condition of the engine (plugs, leaks in
hoses, etc.).
2) Make sure all accessories are OFF.
3) Warm up the engine and run it for three minutes
at 2,500—3,000 rpm in neutral.
4) Check the initial ignition timing and adjust if
necessary.
Inspection and Adjustment
Caution
Disconnect the air bypass solenoid connec-
tor when checking and adjusting the idle
speed.
1. Check that the idle speed is within specification.
Specification:
MTX—800 +58 rpm
ATX—900 +58 rpm (P range)
2. If the idle speed is not within specification, remove
the blind cap from the throttle body and adjust it
by turning the air adjust screw.
IDLE MIXTURE
Because an automatic compensation function
for air/fuel mixture is built into the engine con-
trol unit, it is not necessary to check and adjust
the idle mixture.
86U04A-049
4B-29

4B INTAKE AIR SYSTEM
INTAKE AIR SYSTEM
76G04B-036
This system controls the air required by the engine for operation. The system consists of the air duct,
air cleaner, air flow meter, throttle body, dynamic chamber, and intake manifold.
COMPONENT DESCRIPTIONS
Component Function Remarks
Air cleaner
Filters
air
into throttle body

Air flow meter
Detects amount
of
intake air;
sends signal
to
engine control unit Intake
air
thermo sensor and fuel pump
switch are integrated

Throttle body
Controls intake
air
quantity Integrated throttle sensor and idle switch

76G04B-037
4B—30

INTAKE AIR SYSTEM 4B
REMOVAL
Caution
Before removing the following parts, release the fuel pressure from fuel system to reduce
the possibility of injury or fire. (Refer to page 4B—45.)
Remove in the sequence shown in the figure.
1. Air flow meter connector
and secondary air hose
2. Air cleaner
3. Air duct
4. Resonance chamber
5. Air flow meter
6. Air hose
7. Vacuum hoses, air hoses,
and water hoses
8. Accelerator cable
9. Throttle sensor connector
10. Throttle body
11. EGR modulator valve
12. Air hose
13. Air bypass solenoid valve
76G04B-038
14. Intake manifold bracket
15. Dynamic chamber bracket
16. Fuel return pipe
17. Dynamic chamber
18. Injector connector
19. Delivery pipe assembly
20. Air valve
21. Intake manifold and gaskets
4B—31

4B FUEL SYSTEM
FUEL SYSTEM
76G04B-057
This system supplies the fuel necessary for combustion at a constant pressure to the injectors. Fuel
is metered and injected into the intake manifold according to the injection control signals from the en-
gine control unit. It consists of the fuel pump, fuel filters, delivery pipe, pulsation damper, pressure
regulator, injectors, fuel pump switch (incorporated in the air flow meter), and the circuit opening relay.
The fuel pump is mounted in the fuel tank to minimize the operating noise of the fuel pump. The injec-
tors are directly supplied with battery voltage through the main relay.
4B—42

FUEL SYSTEM 4B
COMPONENT DESCRIPTIONS
Component Function Remarks
Air flow meter
Detects amount
of
intake
air;

sends signal
to
engine control unit Intake
air
thermo sensor and fuel pump
switch
are
integrated

Atmospheric pressure sensor
Detects atmospheric pressure; sends sig-nal
to
engine control unit

Circuit opening relay
Voltage
for
fuel pump while engine running

Clutch switch
Detects in-gear condition; sends signal
to
engine control unit Switch
ON
when clutch pedal released

Engine control unit
Detects signals from input sensors and switches; controls injector operation

Fuel filter
Filters particles from fuel

Fuel pump
Provides fuel
to
injectors • Operates while engine running
• Installed
in
fuel tank

Idle switch
Detects when throttle valve fully closed;
sends signal
to
engine control unit
Installed
in
throttle sensor

Ignition coil (-) terminal
Detects engine speed; sends signal
to
engine control unit

Ignition switch (ST position)
Sends engine cranking signal
to
engine control unit

Inhibitor switch
Detects in-gear condition; sends signal
to
engine control unit
Switch
ON in "N" or "P"
range

Injector
Injects fuel into intake port • Controlled
by
signals from engine control unit • High-ohmic injector

Intake air thermo sensor
Detects intake
air
temperature;
sends signal
to
engine control unit Installed
in air
flow meter

Main relay
Supplies electric current
to
injectors and engine control unit

Neutral switch
Detects in-gear condition; sends signal
to
engine control unit
Switch
ON
in-gear

Oxygen sensor
Detects Oxygen concentration; sends sig-nal
to
engine control unit
Zirconia ceramic and platinum coating

Pressure regulator
Adjusts fuel pressure supplied
to
injectors

Pulsation damper
Absorbs fuel pulsation

Throttle sensor
Detects throttle valve opening angle; sends signal
to
engine control unit
Integrated idle switch

Water thermo sensor
Detects coolant temperature;
sends signal
to
engine control unit

Water thermo switch
Detects radiator coolant temperature; sends signal
to
engine control unit ON: above 17°C (63°F)

76G04B-058
4B—43

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

FUEL SYSTEM 4B
86U04A-068
FUEL PRESSURE RELEASE AND SERVICING
FUEL SYSTEM
Fuel in the fuel system remains under high pressure
even when the engine is not running.
a) Before disconnecting any fuel line, release the fuel
pressure from the fuel system to reduce the pos-
sibility of injury or fire.
1. Start the engine.
2. Disconnect the circuit opening relay.
3. After the engine stalls, turn OFF the ignition
switch.
4. Reconnect the circuit opening relay.
b) Use a rag as protection from fuel spray when dis-
connecting the hoses.
Plug the hoses after removal.
c) When inspecting the fuel system, use the SST.
86U04A-069
4B—45