1987 MAZDA 626 fuel consumption

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

FUEL SYSTEM
4C

TROUBLESHOOTING
Checking the condition of the wiring harness and connectors before checking the sensors or switches.
Note
If
no
problem
is
found, continue with inspection
of the
next system
of
Troubleshooting
Guide. (Refer
to
page 4C—10,
and 11)

Possible cause 0 CO £ O ** CO £ O "5
Page


o CO c 0> (A
S o c
w O M C
.fc <0 "o
^ o w c 0) <0 c « o>
Im O CO c w w
0>
!
41 10 o E k 0) £ **
d>
5 <0 O E ^ 0) £
w 0

Fuel
pump
Injector Fuel
pressure

Engine control
unit terminal
a. E 3 a
a> » c

Transfer

pump

sv
(4WS)
ha c o o
if Qj
«> S£

< g. X O £ 1-ID a 5
Fuel
pump
Injector Fuel
pressure

1Q 3C,3E 3F,3H 3B ID k_ H
Transfer

pump

sv
(4WS) 3
C
U.
3

Symptom *C—103 4C—110 4C—107 4C—104 4C—107 4C—106 4C-56 4C-57 4C-54 4C-98 40-59
Hard start
or
won't start (Cranks
OK)
— — —-— g — 1 7 — 2 8 6 3 4 5
Engine During warm
up
4 — — — 3 — — 2 1 — 5 — — — —
stalls After warm
up
1 — — — — — — 3 2 — 4 — — — —
Rough During warm
up
5 — — — 3 — — 2 1 — 4 — — — —
a> 3 Idle After warm
up
1 6 — — 4 — — 3 2 — 5 — — — —
•o a> •o (0 a> c -»
Poor acceleration, hesi-tation,
or
lack
of
power 1 — — 3 5 — — 4 2 — 6 — — — — •o a> •o (0 a> c -» Runs
rough on
deceleration 1 — — — — — — 2 — — 3 — — — —
Afterburn on deceleration 1 — — — — — — 2 — — 3 — — — —
Poor fuel consumption 6 — 5 — 4 — — 2 1 — 3 — — — —
Engine stalls
or
runs rough after hot starting 1 5 — — — — — 3 2 — 4 — — — —
Falls emission test — — 1 — — 2 — 3 — — 4 — — — —
Hard start
or
won't
start (Cranks
OK)
— — — — 9 — 1 7 — 2 8 6 3 4 5
Engine During warm
up
4 — — — 3 — — 2 1 — 5 — — — —
stalls After warm
up
1 — — — — — — 3 2 — 4 — — — —
Rough During warm
up
— — — 3 — — 2 1 — 4 — — — —
a> 3 Idle After warm
up
1 6 — — 4 — — 3 2 — 5 — — — —
•o a> •o a
Poor acceleration, hesi-tation,
or
lack
of
power 1 — — — 4 — — 3 2 — 5 — — — —
a> Runs rough on deceleration 1 — — — — — — 2 — — 3 — — — —
Afterburn on deceleration 1 — — — — — — 2 — — 3 — — — —
Poor fuel consumption 5 — — — 4 — — 2 1 — 3 — — — —
Engine stalls
or
runs rough after
hot
staring 1 5 — — — — — 3 2 — 4 — — — —
Falls emission test 1 ?
76G04C-089
4C—51

4C DECELERATION CONTROL SYSTEM
DECELERATION CONTROL SYSTEM
Distributor
(Ne signal)
Idle switch
QSO-Water thermo sensor
=5
A/C switch
Engine control unit
Detection of
fuel cut
condition Determi-
nation of
fuel cut
speed
* *
1
T
No.3

I
No.4
No.2
The fuel cut system is provided as a deceleration control system.
This system is to improve fuel consumption.
86U04A-121
4C—72

TROUBLESHOOTING GUIDE 4D
TROUBLESHOOTING GUIDE
Condition Condition Cause Remedy
Hard starting Fuel filter
Clogged Replace
Water or air in filter Repair
Fuel injection pump Faulty fuel cut solenoid Replace Incorrect injection timing Adjust
Air in pump Bleed
Faulty pump Replace
Fuel injection nozzle Seized needle valve Replace
Fuel dripping from nozzle Replace Incorrect valve opening pressure Adjust
Faulty glow plug Replace
Faulty cold start device Adjust or replace
Faulty supercharging system Refer to page 4D—10
Rough idle Fuel filter (Refer to "Hard starting") Fuel injection pump (Refer to "Hard starting")
Fuel injection nozzle
Seized needle valve Replace
Incorrect valve opening pressure Adjust
Improper mounting to nozzle holder Repair
Leakage of nozzle holder copper washer Replace
Fuel injection pipe Cranks Replace
Leaking from joint Repair
Improper idle speed adjustment Adjust
Engine knocking Incorrect injection timing Adjust
Low quality fuel Replace
Incorrect injection nozzle opening pressure Ajust
Seized injection nozzle needle valve Replace
Fuel dripping from injection nozzle Replace
Faulty supercharging system Refer to page 4D—10
High fuel Fuel injection pump consumption Incorrect injection timing Adjust consumption High idle speed Adjust, Inspect the dashpot
Fuel injection nozzle Incorrect valve opening pressure Repair
Fuel dripping from nozzle Replace
Leakage of nozzle holder copper washer Replace
Fuel leaking from connection Repair
Clogged fuel filter Replace
Clogged air cleaner Replace
Poor acceleration Fuel injection nozzle (Refer to "Hard starting")
Fuel injection pump (Refer to "Hard starting")
Fuel injection pipe (Refer to "Rough idle") Fuel filter (Refer to "Hard starting") Clogged air cleaner Clean or replace
Faulty supercharging system Refer to page 4D—10
Excessive exhaust Clogged air cleaner Clean or replace
smoke Improper injection timig Adjust
Faulty nozzle or nozzle holder Adjust or replace
Faulty supercharging system Refer to page 4D—10
76G04D-003
4D-3