1987 MAZDA 626 fuel

4C TROUBLESHOOTING GUIDE
The Troubleshooting Guide lists the systems most likely to cause
a
given symptom. After finding which
system(s)
to
check, refer
to the
pages shown
for
detailed guides.
iSystem
S UJ 1-tn > tn

INTAKE

AIR
SYSTEM
FUEL
SYSTEM

o oc a
_i o oc 1-z o o oc o i-<
-i
o UJ OC Ul oc 3 (0 tn Ul oc a.
IDLE

SPEED
CONTROL
(ISC)
SYSTEM
ELECTRONIC
SPARK
ADVANCE

(ESA)

CONTROL
SYSTEM

EXHAUST

GAS
RECIRCULATION

(EGR)

SYSTEM

EVAPORATIVE

EMISSION

CONTROL
(EEC)
SYSTEM
POSITIVE
CRANKCASE
VENTILATION
(PCV)
SYSTEM
DECELERATION
CONTROL
SYSTEM

EXHAUST

SYSTEM

VARIABLE

INERTIA
CONTROL
(VIC)
SYSTEM

Page

4C—31 4C—49 4C—68 4C—44 4C—75 4C—77 4C—80 4C—86 4C—72 4C—87
&
89
4C—39
2 3 2 — — 1 — — — — — —
3
4 3 — 1 — 2 — _ _ — — 3 5 4 — 2 — 3 — 1 — — —
4 5 4 -1 — 3 — 2 — — -4 6 5 — 2 — 3 4 1 — — —
o z 5 2 3 — 1 — — — — — — —
E o 6 3 4 — — — 1 2 — — 6 5
Q-E >> 7 4 3 — 2 — — — — 1 — —
(0 8 3 4 — 1 — — — — 2 — —
9 — 2 — — — 3 — — 1 5 4
10 — 2 1 — — — — — — — —
11 — — — — 1 — — — — — —
12 6 7 — 4 — 2 5 _ 3 1
76G04C-010
The numbers
of the
list show
the
priorities
of
inspections, from
the
most possible system
to
that with
the lowest possibility.
These were determined
on the
following basis:
• Ease
of
inspection
•
Most possible system
•
Most possible point
in
system
4C—10

4C TROUBLESHOOTING WITH SST
2. Second digit of malfunction code (ones position)
The digit in the ones position of the malfunction code represents the number of times the buzzer
is on 0.4 sec during one cycle.
ON
OFF
1 cycle Malfunction code
1 2 3 cycle break
Malfunction
code: 03
n^j
0.4 0.4 sdc. sec.
4.0 sec.
76G04C-015
3. First digit of malfunction code (tens position)
The digit in the tens position of the malfunction code represents the number of times the buzzer
is on 1.2 sec during one cycle.
It should also be noted that the light goes off for 1.6 sec. between the long and short pulses of
the buzzer.
1 cycle Malfunction code
1 2
~U 0.4
1.2 sec. sec h
1 2|
flfl
First digit
1.6 sec.
cycle break
Malfunction
code: 22
nr
4.0 sec.
Second
digit
76G04C-016
CODE NUMBER
Malfunction display
Sensor or
subsystem Self-diagnosis Fail-safe Malfunction
code no.
Malfunction code output signal pattern
Sensor or
subsystem Self-diagnosis Fail-safe
02 o°nfJLJJL
Ne signal No Ne signal from crank angle sensor during craking
03 oppJUllUl
G signal No G signal Cancels sequencial
injection
05
Knock sensor (only
leaded fuel)
Open or short circuit • Retards ignition timing 4°
76G04C-017
4C—14

4C IDLE ADJUSTMENT
76G04C-048
Idle speed
Automatic
Control
Function
Engine Control Unit
76G04C-049
76G04C-050
3. Remove the blind cap and adjust the initial idle
speed to specification by turning the air adjust
screw.
Initial idle speed: 750 ± 50 rpm
4. After adjusting the idle speed, install the blind cap
and disconnect the jumper wire from the test con-
nector.
5. Recheck the idle speed.
6. If not within specification, check the idle speed con-
trol (ISC) system.
IDLE MIXTURE (Unleaded Fuel)
An automatic compensation function for air/fuel
mixture is built into the engine control unit, it
is not necessary to check and adjust the idle
mixture.
IDLE MIXTURE (Leaded Fuel)
Note
Before checking or adjusting the idle mixture,
check and adjust the idle speed, if necessary.
1. Insert a gas analyzer pick-up into the tail pipe.
2. Check that the CO and HC concentrations are with-
in specification.
CO concentration: 1.5 ± 0.5%
HC concentration: Less than 1,000 PPM
3. If the CO or HC concentration is not within specifi-
cation, turn the adjust screw
with
the SST to adjust.
76G04C-051
4C-30

4C INTAKE AIR SYSTEM
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 4C—52.)
Remove in the sequence shown in the figure, referring to the removal note.
1. Air cleaner
2. Air flow sensor
3. Air hoses
4. Connectors (Idle switch,
ISC, Throttle sensor)
5. Water hoses
6. Vacuum hoses
7. Accelerator cable
8. Throttle body
9. Gasket
10. PCV hose
4C-32
11. Vacuum pipe assembly
(Unleaded fuel)
12. Dynamic chamber brackets
13. Connectors (Knock sensor,
Intake air thermo sensor)
14. Dynamic chamber
15. One-way check valve
16. Gasket
17. Wiring harness
(for injectors)
18. Fuel hoses
76G04C-053
19. Delivery pipe assembly
mounting bolt.
20. Heat insulator
21. Injectors
22. Delivery pipe assembly
23. EGR pipe
24. Intake manifold bracket
25. Solenoid valve
26. Intake manifold
27. Gasket
28. Air duct
29. Resonance chamber

INTAKE AIR SYSTEM 4C
76G04C-054
76G04C-055
76G04C-056
Removal Note
Water hose
Before disconnecting the water hose, drain two liters
of engine coolant.
Delivery pipe assembly.
1. Separate the fuel return pipe from the delivery pipe
assembly.
2. Remove the delivery pipe assembly and the fuel
return pipe.
PARTS INSPECTION
Air Cleaner Element
1. Check the condition of the air cleaner element.
2. Blow out the dust with compressed air, if
necessary.
Caution
a) The air cleaner must be replaced at the in-
tervals outlined in the maintenance
schedule.
b) Never drive the vehicle without the air
cleaner element, otherwise, damage to the
air flow sensor (hot wire) will occur.
c) Never use an oil permeated air cleaner ele-
ment, otherwise, contamination of the hot
wire will occur.
4C—33

4C INTAKE AIR SYSTEM
Installation Note
Water hose spring clamps
Face the clamp end as shown in the figure.
Gasket
Use new gaskets at the intake manifold, dynamic
chamber, and throttle body.
86U04A-056
• . v 1
Engine 1 Ml' ' •-
hanger ^ •
• i::£?^Solenoid valve bracket
Air cleaner. r^I. ^jUvW;
Th V
Ground harnesses
Make sure that the ground harnesses are tightened
securely at the following positions.
(1) Air cleaner upper case
(2) Solenoid valve braket
(3) Engine hanger
76G04C-062
Solenoid valve connectors
Connect the solenoid valve connectors at the posi-
tions shown in the figure.
76G04C-063
Inspection after installation
1. After completing installation, fill up the engine with
the specified engine coolant.
2. Warm up the engine and run it at idle.
3. Check for any vacuum, coolant, or fuel leaks.
76G04C-064
4C-38

7C VIC SYSTEM
COMPONENT DESCRIPTION
Component Function Remark
Dynamic chamber Provides chamber for VIC system operation Integrates one-way check valve
Engine control unit Monitors engine rpm, controls solenoid valve Unleaded fuel: ON at above 5200 rpm Leaded fuel: ON at above 5400 rpm
Intake manifold Provides short and long length of intake travel Integrates shutter valve
One-way check valve Holds vacuum in vacuum chamber Installed between dynamic chamber and vacuum chamber
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to control unit Installed in distributor
Solenoid valve (Vlfc) Controls vacuum to shutter valve actuator
Shutter valve Closes short intake port
Shutter valve actuator Actuates shutter valve according to
vacuum from solenoid valve
76G04C-066
TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the sensor or switches.
Note
Make the system inspection first. If no problem is found, continue with inspection of the
next system of the Troubleshooting Guide. (Refer to pages 4C—10 and 11.)
Possible cause
\Page\.
Symptom
Vacuum chamber (Vacuum leak)
Shutter valve actuator
One-way check valve
Solenoid valve (VIC) Engine control unit (1C)
System
Inspection
Possible cause
\Page\.
Symptom
Vacuum chamber (Vacuum leak)
Shutter valve actuator
One-way check valve Vacuum ' Electric signal | signal
Engine control unit (1C)
System
Inspection
Possible cause
\Page\.
Symptom 4C—42 4C—41 4C—43 4C—42 4C-98 4C—41
Rough idle
During warm up 2 3 4 — — — 1 Rough idle After warming up 2 3 4 — — — 1
Poor acceleration, hesitation,
or lack of power 6 5 7 2 3 4 1
Poor fuel consumption 6 5 7 2 3 4 1
76G04C-067
4C—40

VIC SYSTEM 4C
System Inspection
1. Warm up the engine to normal operating temper-
ature and run it at idle.
2. Check that the rod has been pulled into the ac-
tuator.
76G04C-068
3. Increase the engine speed and check that the rod
is released above specification.
Specification:
Approx. 5,200 rpm....Unleaded fuel
Approx. 5,400 rpm....Leaded fuel
76G04C-069
Shutter Valve Actuator
1. Disconnect the vacuum hose from the actuator,
and connect a vacuum pump to the actuator.
2. Apply approx. 200 mmHg (7.9 inHg) vacuum
and check that the rod is pulled into the actuator.
76G04C-070
VIC Solenoid Valve
1. Disconnect the vacuum hoses from the solenoid
valve.
2. Blow through the valve from port A and check that
air flows from port B.
76G04C-071
4C—41